PATENT DOCUMENT

Publication Number: US-10237711-B2
Application Number: US-201514871931-A
Country: US
Kind Code: B2

Title: Dynamic types for activity continuation between electronic devices

Abstract:
The described embodiments transfer an activity from a source electronic device to a companion electronic device. The source electronic device receives activity information describing an activity performed in a first application at the source electronic device, determines an activity identifier for the activity information, and broadcasts an activity advertisement comprising the activity identifier. Upon receiving the activity advertisement, the companion electronic device determines whether a second application that is associated with the first application is available at the companion electronic device. If the second application is available, the companion electronic device requests extended activity data from the source electronic device. The source electronic device responds by sending extended activity data from the first application to the companion electronic device. Then, the companion electronic device uses the extended activity data to configure the second application and commences performing the activity with the second application at the companion electronic device.

Claims:
What is claimed is: 
     
       1. A method, comprising:
 in a companion electronic device, performing operations for: 
 receiving an activity advertisement message from a source electronic device, the activity advertisement message comprising dynamic type information describing an attribute of an activity; 
 evaluating the dynamic type information to determine whether the companion electronic device includes an application configured to perform a corresponding activity by:
 comparing a dynamic type identifier for the activity with a set of dynamic type identifiers for activities that are available at the companion electronic device; and 
 in response to determining that the dynamic type identifier is not in the set of dynamic type identifiers, comparing the dynamic type identifier to a set of activity identifiers for activities that are available at the companion electronic device; 
 
 in response to determining that the companion electronic device includes the application configured to perform the corresponding activity, requesting extended activity data for the activity from the source electronic device; 
 using the extended activity data received from the source electronic device to configure the application configured to perform the corresponding activity on the companion electronic device to perform the corresponding activity; and 
 performing the corresponding activity using the application configured to perform the corresponding activity on the companion electronic device. 
 
     
     
       2. The method of  claim 1 ,
 wherein the dynamic type identifier for the activity comprises an identifier for a first application performed on the source electronic device and a descriptor for a dynamic type; and 
 wherein each dynamic type identifier from the set of dynamic type identifiers comprises an identifier for a corresponding application that is available on the companion electronic device and a descriptor for a corresponding dynamic type in a set of dynamic types for the corresponding application. 
 
     
     
       3. The method of  claim 2 ,
 wherein each activity identifier in the set of activity identifiers is added to the set of activity identifiers when an application corresponding to the activity identifier is installed on the companion electronic device. 
 
     
     
       4. The method of  claim 3 , wherein the first application provides the dynamic type information during runtime. 
     
     
       5. The method of  claim 1 , further comprising:
 in the companion electronic device, performing operations for: 
 receiving a table of activities recently performed at the source electronic device; and 
 using an index that identifies an entry in the table of activities to determine the dynamic type identifier for the activity, wherein the dynamic type information comprises the index. 
 
     
     
       6. The method of  claim 1 , wherein the advertisement message comprises a hash of a character string, the character string comprising the dynamic type information and an identifier that identifies a first application that performs the activity on the source electronic device. 
     
     
       7. The method of  claim 1 , further comprising:
 in the companion electronic device, performing operations for: 
 receiving a second activity advertisement message from a second source electronic device, the second activity advertisement message comprising dynamic type information describing an attribute of an activity performed on the second source electronic device; and 
 based on comparing a first timestamp included with the activity advertisement message and a second timestamp included with the second activity advertisement message, determining that the activity performed in a first application on the source electronic device is a most recent activity of the activity performed on the source electronic device and the activity performed on the second source electronic device. 
 
     
     
       8. The method of  claim 1 , further comprising:
 in the companion electronic device, performing operations for: 
 prior to requesting the extended activity data, presenting an indication that the activity is resumable, the indication presented on the companion electronic device; and 
 upon receiving an acceptance of the indication, performing the using the extended activity data and the performing the corresponding activity. 
 
     
     
       9. The method of  claim 1 , wherein the activity advertisement and the extended activity data are communicated using a Bluetooth low-energy (BLE) network protocol. 
     
     
       10. A companion electronic device comprising:
 a processing subsystem; and, 
 a networking subsystem; 
 wherein the processing subsystem and the networking subsystem are configured to perform operations for:
 receiving an activity advertisement message from a source electronic device, the activity advertisement message comprising dynamic type information describing an attribute of an activity; 
 evaluating the dynamic type information to determine whether the companion electronic device includes an application configured to perform a corresponding activity by:
 comparing a dynamic type identifier for the activity with a set of dynamic type identifiers for activities that are available at the companion electronic device; and 
 in response to determining that the dynamic type identifier is not in the set of dynamic type identifiers, comparing the dynamic type identifier to a set of activity identifiers for activities that are available at the companion electronic device; 
 
 in response to determining that the companion electronic device includes the application configured to perform the corresponding activity, requesting extended activity data for the activity from the source electronic device; 
 using the extended activity data received from the source electronic device to configure the application configured to perform the corresponding activity on the companion electronic device to perform the corresponding activity; and 
 performing the corresponding activity using the application configured to perform the corresponding activity on the companion electronic device. 
 
 
     
     
       11. The companion electronic device of  claim 10 ,
 wherein the dynamic type identifier for the activity comprises an identifier for a first application performed on the source electronic device and a descriptor for a dynamic type; and 
 wherein each dynamic type identifier from the set of dynamic type identifiers comprises an identifier for a corresponding application that is available on the companion electronic device and a descriptor for a corresponding dynamic type in a set of dynamic types for the corresponding application. 
 
     
     
       12. The companion electronic device of  claim 11 ,
 wherein each activity identifier in the set of activity identifiers is added to the set of activity identifiers when an application corresponding to the activity identifier is installed on the companion electronic device. 
 
     
     
       13. The companion electronic device of  claim 12 , wherein the advertisement message comprises a hash of a character string, the character string comprising the dynamic type information and an identifier that identifies a first application that performs the activity on the source electronic device. 
     
     
       14. The companion electronic device of  claim 10 , wherein the processing subsystem and the networking subsystem are further configured to perform operations for:
 receiving a table of activities recently performed at the source electronic device; and 
 using an index that identifies an entry in the table of activities to determine the dynamic type identifier for the activity, wherein the dynamic type information comprises the index. 
 
     
     
       15. The companion electronic device of  claim 10 , wherein the processing subsystem and the networking subsystem are further configured to perform operations for:
 receiving a second activity advertisement message from a second source electronic device, the second activity advertisement message comprising dynamic type information describing an attribute of an activity performed on the second source electronic device; and 
 based on comparing a first timestamp included with the activity advertisement message and a second timestamp included with the second activity advertisement message, determining that the activity performed in a first application on the source electronic device is a most recent activity of the activity performed on the source electronic device and the activity performed on the second source electronic device. 
 
     
     
       16. The companion electronic device of  claim 10 , wherein the activity advertisement and the extended activity data are communicated using a Bluetooth low-energy network protocol. 
     
     
       17. A non-transitory computer-readable medium including one or more sequences of instructions that, when executed by one or more processors of a companion electronic device, causes:
 receiving an activity advertisement message from a source electronic device, the activity advertisement message comprising dynamic type information describing an attribute of an activity; 
 evaluating the dynamic type information to determine whether the companion electronic device includes an application configured to perform a corresponding activity by:
 comparing a dynamic type identifier for the activity with a set of dynamic type identifiers for activities that are available at the companion electronic device; and 
 in response to determining that the dynamic type identifier is not in the set of dynamic type identifiers, comparing the dynamic type identifier to a set of activity identifiers for activities that are available at the companion electronic device; 
 
 in response to determining that the companion electronic device includes the application configured to perform the corresponding activity, requesting extended activity data for the activity from the source electronic device; 
 using the extended activity data received from the source electronic device to configure the application configured to perform the corresponding activity on the companion electronic device to perform the corresponding activity; and 
 performing the corresponding activity using the application configured to perform the corresponding activity on the companion electronic device. 
 
     
     
       18. The non-transitory computer-readable medium of  claim 17 ,
 wherein the dynamic type identifier for the activity comprises an identifier for a first application performed on the source electronic device and a descriptor for a dynamic type; and 
 wherein each dynamic type identifier from the set of dynamic type identifiers comprises an identifier for a corresponding application that is available on the companion electronic device and a descriptor for a corresponding dynamic type in a set of dynamic types for the corresponding application. 
 
     
     
       19. The non-transitory computer-readable medium of  claim 18 ,
 wherein each activity identifier in the set of activity identifiers is added to the set of activity identifiers when an application corresponding to the activity identifier is installed on the companion electronic device. 
 
     
     
       20. The non-transitory computer-readable medium of  claim 19 , wherein the advertisement message comprises a hash of a character string, the character string comprising the dynamic type information and an identifier that identifies a first application that performs the activity on the source electronic device. 
     
     
       21. The non-transitory computer-readable medium of  claim 17 , wherein the one or more sequences of instructions that, when executed by the one or more processors of the companion electronic device, further causes:
 receiving a table of activities recently performed at the source electronic device; and 
 using an index that identifies an entry in the table of activities to determine the dynamic type identifier for the activity, wherein the dynamic type information comprises the index. 
 
     
     
       22. The non-transitory computer-readable medium of  claim 17 , wherein the one or more sequences of instructions that, when executed by the one or more processors of the companion electronic device, further causes:
 receiving a second activity advertisement message from a second source electronic device, the second activity advertisement message comprising dynamic type information describing an attribute of an activity performed on the second source electronic device; and 
 based on comparing a first timestamp included with the activity advertisement message and a second timestamp included with the second activity advertisement message, determining that the activity performed in a first application on the source electronic device is a most recent activity of the activity performed on the source electronic device and the activity performed on the second source electronic device.

Description:
PRIORITY CLAIM 
     The instant application is a continuation in part of, and hereby claims priority to, pending U.S. patent application Ser. No. 14/586,566, which was filed on 30 Dec. 2014. The instant application also claims priority to U.S. provisional patent application No. 62/005,781, which was filed on 30 May 2014, to which parent application Ser. No. 14/586,566 claims priority. The instant application further claims priority to U.S. provisional patent application No. 62/171,873, which was filed on 5 Jun. 2015. These applications are each incorporated by reference. 
     RELATED APPLICATIONS 
     The instant application is related to pending U.S. patent application Ser. No. 14/586,566, which is titled “Activity Continuation Between Electronic Devices,” by inventors Marc J. Krochmal, Christopher S. Linn, John J. Iarocci, Geoffrey Stahl, and Jacques P. Gasselin de Richebourg, and filed on 30 Dec. 2014, the contents of which are incorporated herein by reference. 
     The instant application is also related to pending U.S. patent application Ser. No. 14/586,511, which is titled “Companion Application for Activity Cooperation,” by inventors Marc J. Krochmal, Christopher S. Linn, John J. Iarocci, Geoffrey Stahl, and Jacques P. Gasselin de Richebourg, and filed on 30 Dec. 2014, the contents of which are incorporated herein by reference. 
     The instant application is also related to pending U.S. patent application Ser. No. 14/475,329, which is titled “Operating-Mode Transitions based on Advertising Information,” by inventors Craig P. Dooley, Akshay Mangalam Srivatsa, Anjali S. Sandesara, and Michael Giles, and filed on 2 Sep. 2014, the contents of which are incorporated herein by reference. 
     The instant application is also related to pending U.S. patent application Ser. No. 14/474,466, which is titled “Predefined Wireless Pairing,” by inventors Jason C. Conn, Akshay Mangalam Srivatsa, Craig P. Dooley, and Michael Giles, and filed on 2 Sep. 2014, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Field 
     The disclosed embodiments relate to electronic devices. More specifically, the disclosed embodiments relate to activity continuation between electronic devices. 
     Related Art 
     Recent advances in computer technology have enabled manufacturers to produce powerful computing devices in various form factors, thereby enabling users to use a device as small and portable as a smartphone or a tablet to perform tasks that once required a desktop or laptop computer. Because of these advances, users often possess and use multiple computing devices, e.g., a smartphone while on the road, a tablet in meetings, and a laptop or desktop computer at a desk. 
     Although a user may possess different devices, each with powerful computing capabilities, in certain cases, the user may find him- or herself using a device that is ill-suited for a task being performed or for the situation that the user is in. For example, the user may start what is intended as a short email on a device such as a smartphone with a small display screen and then, due to the size of the display screen, may have a difficult time entering and editing text in the email when the email turns out to be longer than anticipated. Alternatively, the user may be reading a web page or watching a movie on a desktop but may have to leave the room in which the desktop is located. Although the user may retrieve another device and start the task, this is cumbersome. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  presents a block diagram illustrating an electronic device in accordance with some embodiments. 
         FIG. 2  presents a block diagram illustrating a network environment in accordance with some embodiments. 
         FIG. 3  presents a flowchart illustrating a process for broadcasting an activity advertisement message in accordance with some embodiments. 
         FIG. 4  presents a flowchart illustrating a process for storing activity information describing activities that are available at a companion electronic device in accordance with some embodiments. 
         FIG. 5  presents a flowchart illustrating a process for requesting extended activity data and transferring an activity in accordance with some embodiments. 
         FIG. 6  presents a flowchart illustrating a process for responding to a request for extended activity data in accordance with some embodiments. 
         FIG. 7  presents a flowchart illustrating a process for determining whether the second application is available at a companion electronic device in accordance with some embodiments. 
         FIG. 8  presents a flowchart illustrating a process for determining the second application using a flag in accordance with some embodiments. 
         FIG. 9  presents a flowchart illustrating a process for determining whether the second application is available when the activity identifier identifies an entry in a structure that stores advertised activities in accordance with some embodiments. 
         FIG. 10  presents a flowchart illustrating a process for determining a most recent activity from two or more activity advertisement messages in accordance with some embodiments. 
         FIG. 11  presents a flowchart illustrating a process for determining whether a second application is available at companion electronic device  204  when dynamic type information is used in accordance with some embodiments. 
         FIG. 12  presents a block diagram illustrating activity information in accordance with some embodiments. 
         FIG. 13  presents a block diagram illustrating an advertised-activity table in accordance with some embodiments. 
         FIG. 14  presents a block diagram illustrating an activity advertisement message in accordance with some embodiments. 
         FIG. 15  presents a block diagram illustrating a resumable-activity indication in accordance with some embodiments. 
         FIG. 16  presents a swim lane diagram illustrating messages exchanged between electronic devices in accordance with some embodiments. 
         FIG. 17  presents a block diagram illustrating electronic devices in proximity to one another in accordance with some embodiments. 
         FIG. 18A  presents example of operations performed when performing activity continuation without using dynamic type information in accordance with some embodiments. 
         FIG. 18B  presents example of operations performed when performing activity continuation using dynamic type information in accordance with some embodiments. 
     
    
    
     In the figures, like reference numerals refer to the same figure elements. 
     DETAILED DESCRIPTION 
     The following description is presented to enable any person skilled in the art to make and use the described embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the described embodiments. Thus, the described embodiments are not limited to the embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. 
     In some embodiments, an electronic device (e.g., electronic device  100  in  FIG. 1  and/or some portion thereof) uses code and/or data stored on a computer-readable storage medium to perform some or all of the operations herein described. More specifically, the electronic device reads the code and/or data from the computer-readable storage medium and executes the code and/or uses the data when performing the described operations. In these embodiments, a computer-readable storage medium can be any device or medium or combination thereof that stores code and/or data for use by an electronic device. For example, the computer-readable storage medium can include, but is not limited to, volatile memory or non-volatile memory, such as semiconductor memories (e.g., flash memory, random access memory (eDRAM, RAM, SRAM, DRAM, DDR, DDR2/DDR3/DDR4 SDRAM, etc.), etc.) and/or magnetic or optical storage mediums (e.g., disk drives, magnetic tape, CDs, DVDs). In the described embodiments, the computer-readable storage medium does not include non-statutory computer-readable storage mediums such as transitory signals. 
     In some embodiments, one or more hardware modules are configured to perform the operations herein described. For example, the hardware modules can comprise, but are not limited to, one or more processors/cores/central processing units (CPUs), application-specific integrated circuit (ASIC) chips, field-programmable gate arrays (FPGAs), caches/cache controllers, memory management units, compute units, embedded processors, graphics processors (GPUs)/graphics cores, pipelines, and/or other programmable-logic devices. When such hardware modules are activated, the hardware modules perform some or all of the operations. In some embodiments, the hardware modules include one or more general-purpose circuits that are configured by executing instructions (program code, firmware, etc.) to perform the operations. 
     In this description, functional blocks may be referred to in describing some embodiments. Generally, functional blocks include one or more interrelated circuits, devices, and/or mechanisms that perform described operations. In some embodiments, at least some of the functional blocks include general-purpose processing circuits that execute program code (e.g., microcode, firmware, applications, etc.) that causes the general-purpose processing circuits to perform the described operations. 
     Overview 
     The described embodiments transfer an activity performed at a source electronic device from the source electronic device to a companion electronic device—a process that is referred to as “continuing” the activity in the companion electronic device. In the described embodiments, to perform the transfer, the source electronic device sends information that describes an activity performed in a first application at the source electronic device to the companion electronic device. The companion electronic device then uses some or all of the information to configure a second application at the companion electronic device to perform a corresponding activity. Generally, the activity includes one or more operations that are performed at least partially at the source electronic device that are transferred to/continued on the companion electronic device. Examples of activities include reading and/or editing a document (e.g., a word processing document, spreadsheet, presentation, or other type of document), composing an email message, an email, voice message or video, drafting a note, accessing (browsing) a website, watching a movie, playing an audio file, or otherwise using an application or app to perform corresponding operations. 
     In some embodiments, when transferring an activity from the source device to the companion device, the source electronic device first broadcasts an activity advertisement message (also referred to as an “activity advertisement”) using a wireless network interface (e.g., Bluetooth low energy (BLE), ZigBee, etc.). In some embodiments, the source electronic device generates an activity identifier for the activity performed in a first application at the source electronic device and includes the activity identifier in the activity advertisement message. The source electronic device generates the activity identifier by performing a set of operations (e.g., a hash operation, etc.) using activity information that describes the activity that is received from the first application. Examples of activity information are described in more detail below with reference to  FIG. 11 . 
     The companion electronic device monitors a network (e.g., a Bluetooth low energy network) for activity advertisement messages on a network interface corresponding to the network interface in the source electronic device from which the activity advertisement was broadcast. Upon detecting the activity advertisement broadcast from the source electronic device, the companion electronic device compares activity identifiers for activities that are available at the companion electronic device to the activity identifier in the activity advertisement message. The companion electronic device uses this comparison to determine whether a second application that can perform an activity corresponding to the activity performed in the first application is available at the companion electronic device. 
     In some embodiments, upon determining that the second application is available, the companion electronic device establishes communication with the source electronic device over a communication channel (e.g., using the same wireless network interface used to receive the activity advertisement message or a different network interface, wireless and/or wired). The companion electronic device then uses the communication channel to request extended activity data for the activity performed in the first application from the source electronic device. In some embodiments, upon receiving the request for extended activity data, the source electronic device uses the same (or a different) communication channel to provide the extended activity data to the companion electronic device. Generally, the extended activity data includes information that can be used to configure the second application in the companion electronic device to continue the activity, such as a document identifier, a scroll position, a uniform resource locator (URL), etc. related to the activity performed in the first application. 
     In some embodiments, the companion electronic device uses the activity identifier and/or the extended activity data to configure the second application to perform an activity corresponding to the activity performed in the first application at the source electronic device. Then, the companion electronic device starts performing the activity in the second application at the companion electronic device. For example, after the companion electronic device configures the second application, a user can use the companion electronic device to continue working on a document that the user was working with at the source electronic device, to continue watching a movie that the user was watching at the source electronic device, to continue browsing a webpage that the user was browsing at the source electronic device, etc. In some embodiments, the companion electronic device sends a notification to the source electronic device to indicate that the activity was transferred to the second application. The notification can cause the source electronic device and/or the first application to perform housekeeping tasks, such as deleting a document draft for the activity, closing an open document for the activity, etc. 
     In some embodiments, the source and companion electronic devices use dynamic type information to describe attributes of activities performed at the devices. Dynamic type information can enable an application to provide conditions under which activity continuation can be made available. For example, a user may have access to a personal email account on a desktop computer but not on a phone. By using dynamic type information to indicate, for example, that the user is composing an email message for a specific account, some embodiments can prevent electronic devices that do not have access to that email account from showing notifications to indicate that the activity of composing the email message can be transferred. 
     By performing the operations described above for continuing an activity performed at the source electronic device at the companion electronic device, the described embodiments enable a user to continue a task seamlessly and without complex user intervention. This enables the user to more easily perform tasks on desired electronic devices, which can improve the user&#39;s overall experience with two or more electronic devices. 
     Electronic Device 
       FIG. 1  presents a block diagram illustrating electronic device  100  in accordance with some embodiments. Electronic device  100  includes processing subsystem  102 , memory subsystem  104 , networking subsystem  106 , and display subsystem  108 . 
     Processing subsystem  102  is a functional block that performs computational operations in electronic device  100 . Processing subsystem  102  includes one or more central processing units (CPUs)/CPU cores, graphics processing units (GPUs)/GPU cores, embedded processors, application specific integrated circuits (ASICs), and/or other computational mechanisms. 
     Memory subsystem  104  is a functional block that stores data and/or instructions for use by other functional blocks in electronic device  100  (e.g., processing subsystem  102 , etc.). Memory subsystem  104  includes volatile memory circuits such as dynamic random access memory (DRAM), static random access memory (SRAM), and/or other types of memory that are used for storing the instructions and data, as well as mechanisms for controlling the memory circuits. In some embodiments, memory subsystem  104  includes a memory hierarchy with one or more caches coupled to the memory circuits. In some of these embodiments, processing subsystem  102  also includes one or more caches that are part of the memory hierarchy. 
     In some embodiments, memory subsystem  104  is coupled to one or more non-volatile high-capacity mass-storage devices (not shown). For example, memory subsystem  104  can be coupled to a magnetic or optical drive, a solid-state drive, or another type of mass-storage device. In these embodiments, memory subsystem  104  can be used by electronic device  100  as fast-access storage for often-used data, while the mass-storage device is used to store less frequently used data. 
     Networking subsystem  106  is a functional block that includes one or more devices configured to couple to and communicate on a wired and/or wireless network (i.e., to perform network operations). For example, networking subsystem  106  can include a Bluetooth™ networking system, a cellular networking system (e.g., a 3G/4G network such as UMTS, LTE, etc.), a universal serial bus (USB) networking system, a networking system based on the standards described in IEEE 802.11, 802.15, etc. (e.g., a ZigBee or Wi-Fi networking system, etc.), an Ethernet networking system, and/or another networking system. Networking subsystem  106  includes processors, controllers, radios/antennas, sockets/plugs, and/or other devices used for coupling to, communicating on, and handling data and events for each supported networking system. In the following description, the mechanisms used for coupling to, communicating on, and handling data and events on the network for each network system are referred to collectively as the “interface” or “network interface” for the network system. 
     Display subsystem  108  is a functional block that includes one or more devices configured to display information on a visual interface for electronic device  100 . For example, in some embodiments, display subsystem  108  includes graphics processors (GPUs), graphics cards, and/or display screens that are used for displaying the information. 
     In some embodiments, communication paths (that include one or more buses, wires, and/or connections) are coupled between the functional blocks in electronic device  100  (processing subsystem  102 , memory subsystem  104 , etc.), as shown by arrow-headed lines between the elements. The communication paths are used to transmit commands, data, event notifications, and/or other information between the elements. 
     Although specific components are used to describe electronic device  100 , in some embodiments, different components and/or subsystems may be present in electronic device  100 . For example, electronic device  100  may include one or more additional processing subsystems  102 , memory subsystems  104 , etc. Additionally, one or more of the subsystems may not be present in electronic device  100  or some or all of the subsystem&#39;s functions may be incorporated in the other subsystems. Moreover, in some embodiments, electronic device  100  may include one or more additional subsystems that are not shown in  FIG. 1 . For example, electronic device  100  can include, but is not limited to, a data collection subsystem, an audio and/or video subsystem, an alarm subsystem, a media processing subsystem, and/or an input/output (I/O) subsystem. 
     Electronic device  100  can be, or can be included in, any device that performs computational operations. For example, electronic device  100  can be, or can be included in, a desktop computer, a laptop computer, a wearable computing device, a tablet computer, a smart phone, a server, a network appliance, a toy, audio-visual equipment (e.g., a receiver, set top box, Apple TV, etc.), automobiles (e.g., a car interface system, navigation system, heads-up display, etc.), home appliances, controllers, etc., and/or combinations thereof. (Apple TV is a registered trademark of Apple Inc. of Cupertino, Calif.). 
     Network Environment 
       FIG. 2  presents a block diagram illustrating a network environment in accordance with some embodiments. As can be seen in  FIG. 2 , network environment  200  includes source electronic device  202 , companion electronic device  204 , and second source electronic device  206  (referred to collectively as “the electronic devices”). In some embodiments, each of the electronic devices is an electronic device similar to electronic device  100 , i.e., has similar subsystems to electronic device  100 . However, this is not required; the described embodiments can use any electronic devices that can perform the operations herein described. 
     Source electronic device  202  and second source electronic device  206  are electronic devices that participate in exchanges of communications with companion electronic device  204  relating to activity transfer operations. In some embodiments, source electronic device  202  (and/or second source electronic device  206 ) is an electronic device that is recognized by companion electronic device  204  and therefore is allowed to participate in an activity transfer operation. For example, both source electronic device  202  and companion electronic device  204  may have been registered with a service provider using the same account and may therefore recognize each other via information stored in each electronic device. For example, in some embodiments, source electronic device  202  and companion electronic device  204  participate in (and recognize each other via information acquired through) a preliminary pairing operation, e.g., a predefined pairing, as described in pending U.S. patent application Ser. No. 14/474,466, which is titled “Predefined Wireless Pairing,” by inventors Jason C. Conn, Akshay Mangalam Srivatsa, Craig P. Dooley, and Michael Giles, and filed on 2 Sep. 2014, the contents of which are incorporated by reference as described above. In some embodiments, source electronic device  202  and companion electronic device  204  may participate in a device-to-device exchange of identification factors (encryption keys, certificates, etc.) so that source electronic device  202  and companion electronic device  204  subsequently recognize each other. 
     Within network environment  200 , companion electronic device  204  can communicate with source electronic device  202  and second source electronic device  206  using wireless communication signals  208  (illustrated using jagged lines labeled “COMMUNICATION SIGNALS  208 ” in  FIG. 2 ). In some embodiments, communication signals  208  are formatted and exchanged (broadcast, transmitted/received, etc.) in accordance with a corresponding wireless protocol—for example, via a wireless network protocol such as Bluetooth, ZigBee, an 802.11-based protocol and/or other wireless network protocols. In some embodiments, some or all of communication signals  208  are communicated as wired communication signals, e.g., signals in wired Ethernet, a wired LAN, a wired WAN, etc. 
     In some embodiments, the activity transfer operations described herein rely on source electronic device  202  and companion electronic device  204  being sufficiently close to each other to enable communication signals  208  (and thus the incorporated messages) sent by each electronic device to be received by the other electronic device. In other words, source electronic device  202  and companion electronic device  204  are in “proximity” to one another, thereby enabling the exchange of messages between the electronic devices. “Proximity” as used herein therefore represents distance(s) at which messages broadcast/sent from a given electronic device can be received by one or more other electronic devices. This distance is dictated by radio equipment (antennas, receivers/transmitters, etc.) in the electronic devices and the particular radio protocol/signals used to broadcast/send the messages, as limited by factors such as environmental conditions (electromagnetic interference, etc.), intermediate objects (furniture, walls, clothing/bags, etc.), etc. For example, in some embodiments, communication signals  208  are exchanged between source electronic device  202  and companion electronic device  204  using a protocol with an expected range of 30 meters, and thus the devices are “in proximity” when the devices are within 30 meters of one another (note, however, that the expected range may be significantly altered by the above-described factors). 
       FIG. 17  presents a block diagram illustrating electronic devices in proximity to one another in accordance with some embodiments. As can be seen in  FIG. 17 , companion electronic device  204  is within range  1702  for radio signals (e.g., communication signals  208 ) for source electronic device  202 , meaning that companion electronic device  204  can receive radio signals sent from source electronic device  202 . In addition, source electronic device  202  is within range  1704  for radio signals (e.g., communication signals  208 ) for companion electronic device  204 , meaning that source electronic device  202  can receive radio signals sent from companion electronic device  204 . As described above, therefore, source electronic device  202  and companion electronic device  204  are “in proximity” to one another, thereby enabling the communication of messages (and corresponding operations) herein described. However, neither source electronic device  202  nor companion electronic device  204  is within range  1706  for radio signals for electronic device  1700 , meaning that neither source electronic device  202  nor companion electronic device  204  is in proximity to electronic device  1700 . Note that ranges  1702 - 1706  in  FIG. 17  are shown using irregular shapes, thereby illustrating that radio signals from the electronic devices have irregular ranges, depending on the electronic device (antenna arrangement, etc.), the above-described factors, etc. 
     In some embodiments, the messages, data, etc. communicated between the electronic devices are encrypted. In these embodiments, some or all of the electronic devices perform corresponding encryption and decryption operations, e.g., by using a shared key, keys derived from a shared key, and/or a one-time key. For example, as described earlier, in some embodiments, source electronic device  202  and companion electronic device  204  participate in a predefined pairing as described in pending U.S. patent application Ser. No. 14/474,466, which is titled “Predefined Wireless Pairing,” by inventors Jason C. Conn, Akshay Mangalam Srivatsa, Craig P. Dooley, and Michael Giles, and filed on 2 Sep. 2014, the contents of which are incorporated by reference as described above. In some embodiments, source electronic device  202  and companion electronic device  204  encrypt and decrypt messages exchanged for activity transfer operations by using one or more encryption keys that source electronic device  202  and companion electronic device  204  acquire while participating in the predefined pairing. 
     Although various electronic devices are shown in  FIG. 2 , in some embodiments different arrangements of electronic devices are used to perform some or all of the operations herein described. For example, in some embodiments, second source electronic device  206  is not present. Generally, the described embodiments include sufficient devices to transition an activity between electronic devices as described herein. 
     Broadcasting an Activity Advertisement Message 
       FIG. 3  presents a flowchart illustrating a process for broadcasting an activity advertisement message in accordance with some embodiments. More specifically, during the process shown in  FIG. 3 , an electronic device such as source electronic device  202  broadcasts an activity advertisement message. Note that the operations shown in  FIG. 3  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., source electronic device  202 , etc.), in some embodiments, other mechanisms perform the operations. For example, one or both of companion electronic device  204  and second source electronic device  206  may perform similar operations to broadcast an activity advertisement message for themselves. 
     The process shown in  FIG. 3  starts when source electronic device  202  receives activity information that describes an activity performed in a first application at source electronic device  202 , i.e., a first application installed on/available at source electronic device  202  (step  300 ). (Examples of activity information are described in more detail below with reference to  FIG. 11 ). In some embodiments, the first application provides or reports the activity information to source electronic device  202 , e.g., provides or reports the activity information to an operating system, a daemon, or other process and/or service at source electronic device  202 . In some embodiments, source electronic device  202  queries the first application for the activity information. Generally, activity information includes information that describes an activity performed at least partially using an electronic device. Examples of activities include reading and/or editing a document (e.g., a word processing document, spreadsheet, presentation, or other type of document), composing an email message, drafting a note, accessing (browsing) a website, watching a movie, playing an audio file, or otherwise using an application or app to perform corresponding operations. 
     Next, source electronic device  202  determines whether to filter the received activity information (step  302 ), which includes using one or more criteria to discard activity information that is not to undergo further processing and/or not to be broadcast in an activity advertisement message. For example, source electronic device  202  may measure a frequency at which the first application provides updates to the activity information, and may discard activity information from the first application when the frequency at which the activity information is updated exceeds a threshold (which may be referred to as “throttling” the activity information from the first application). As another example, source electronic device  202  may discard activity information that is duplicative or repetitive, that does not contain significant changes to previously reported activity information (e.g., automatic reports of “no change,” reports of simple/basic operations/changes, etc.), that reports facts already known by source electronic device  202 , etc. As yet another example, in some embodiments, source electronic device  202  filters the activity information based on an indication that an activity described by the activity information is not to be advertised. For example, in some embodiments, source electronic device  202  and/or a user of source electronic device  202  may configure certain activities and/or certain kinds of activities as activities that are not to be advertised. As yet another example, in some embodiments, source electronic device  202  ranks some or all activities for which activity information exists (i.e., some or all of the activities that can be advertised) and discards one or more of these activities based on the ranking. For example, source electronic device  202  can assign a higher ranking to activities that a user has previously continued and a lower ranking to activities that a user has previously not continued. In some of these embodiments, source electronic device  202  uses messages from companion electronic device  204  to determine which advertised activities were previously continued and which advertised activities were previously not continued, e.g., messages such as those described below with reference to  FIG. 5 , step  510 . 
     If source electronic device  202  filters, e.g., discards, the activity information (step  302 , yes), the process ends. Otherwise, if source electronic device  202  does not filter the activity information (step  302 , no), source electronic device  202  stores some or all of the activity information in a structure (step  304 ). For illustrative purposes, we describe embodiments that store the activity information in an entry in a table, which we will refer to as the “advertised-activity” table. Note, however, that embodiments are not limited to using a table for storing activity information. Some embodiments use a different storage mechanism/structure for storing the activity information, such as an associative array, a content-addressable memory, etc. 
     In some embodiments, while storing the activity information, source electronic device  202  overwrites and/or removes activity information previously stored in the advertised-activity table. For example, source electronic device  202  can use a least-recently-used (LRU) algorithm to overwrite and/or remove entries from the advertised-activity table. Examples of advertised-activity tables are described in more detail below with reference to  FIG. 12 . 
     Next, source electronic device  202  determines an activity identifier for the activity information (step  306 ). Generally, the activity identifier includes information from the activity information that identifies the first application and the activity performed in the first application. In some embodiments, source electronic device  202  generates the activity identifier by reducing the activity information into a smaller, encoded representation that can be broadcast more efficiently than the full activity information. In some of these embodiments, the encoded representation is a hash of the activity information, i.e., the output of a hash function (e.g., MD4, MD5, SHA, MurmurHash, etc.) whose input comprises the activity information. In some embodiments, source electronic device  202  stores the activity identifier along with the activity information in the advertised-activity table (or whatever structure source electronic device  202  uses to store the activity information). Examples of activity identifiers are described in more detail below with reference to  FIG. 12 . 
     In some embodiments, the activity identifier comprises a representation of a domain name. For example, in some embodiments, when the activity performed in the first application includes using a resource at a domain, the activity information comprises a domain name, e.g., at least a portion of a uniform resource locator (URL), of the domain. In some embodiments, source electronic device  202  determines the activity identifier by including some or all of the domain name in the activity identifier. For example, the activity identifier can be a hash of some or all of the URL for the resource. 
     In some embodiments, the activity identifier identifies an entry in a structure where source electronic device  202  stored the activity information (e.g., as described above with reference to step  304 ). For example, the activity identifier can identify the entry in the advertised-activity table where source electronic device  202  stored the activity information. The activity identifier can also include an identifier for the advertised-activity table itself. In some embodiments, to identify the entry in the structure where source electronic device  202  stored the activity information, the activity identifier includes: (1) a hash of the data in the advertised-activity table to identify the advertised-activity table, and (2) an index for the entry in the advertised-activity table that stores the activity information. 
     Source electronic device  202  next includes the activity identifier into an activity advertisement message (step  308 ). In some embodiments, the activity advertisement message includes other data in addition to the activity identifier. For example, in some embodiments, the activity advertisement message includes a flag that is used to indicate when the activity identifier includes a representation of domain name for an online resource related to the activity. In these embodiments, source electronic device  202  asserts the flag (e.g., sets the flag to a predetermined value such as 1) to indicate that the activity identifier includes a representation of a domain name. In some embodiments, source electronic device  202  asserts a flag in the activity advertisement message to indicate that the advertised activity can be continued in a way that source electronic device  202  will separately provide to companion electronic device  204 , e.g., by source electronic device  202  including corresponding instructions in the extended activity data (extended activity data is described in more detail below). 
     In some embodiments the activity advertisement message includes a timestamp for the activity/activity information. The timestamp, which can express an absolute time or a relative time, can indicate the time that the activity was last performed in the first application, e.g., the last time that a document was edited, a website was accessed, a movie watched, etc. In some embodiments the timestamp is independent of the activity/activity information, i.e., the timestamp indicates the time that a user last interacted with source electronic device  202 , regardless of whether the user&#39;s last interaction included the user performing the activity. 
     Source electronic device  202  then broadcasts the activity advertisement message (step  310 ). For example, source electronic device  202  can broadcast the activity advertisement message using communication signals  208 . In some embodiments, source electronic device  202  broadcasts/advertises the activity advertisement message in network environment  200  so that nearby devices in network environment  200  can receive the activity advertisement message. For example, in these embodiments, source electronic device  202  uses a Bluetooth™ communication channel such as Bluetooth Low Energy (BLE) to broadcast the activity advertisement message. Some embodiments may broadcast the activity advertisement message on a different communication channel, such as a peer-to-peer network, a LAN, the Internet, etc. Note that activity broadcasts can happen more than once, e.g., source electronic device  202  can broadcast the same activity advertisement message multiple times and/or periodically. 
     Building an Available-Activity Table 
     In some embodiments, companion electronic device  204  stores available activity information, e.g., activity information describing activities that are available at companion electronic device  204  (examples of activity information are described in more detail below with reference to  FIG. 11 ). For example, in some embodiments, companion electronic device  204  stores activity identifiers for the available activity information. For illustrative purposes, we describe companion electronic device  204  storing the available activity information in a table, which we refer to as the “available-activity” table (examples of available-activity tables are described in more detail later in this disclosure). Note that, although we describe embodiments that store available activity information in an available-activity table, embodiments are not limited to using a table for storing the available activity information. Some embodiments can use other structures for storing the available activity information, such as an associative array, a content-addressable memory, etc. 
       FIG. 4  presents a flowchart illustrating a process for storing activity information describing activities that are available at companion electronic device  204  into an available-activity table in accordance with some embodiments. Note that the operations shown in  FIG. 4  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., companion electronic device  204 , etc.), in some embodiments, other mechanisms perform the operations. For example, one or both of source electronic device  202  and second source electronic device  206  may perform similar operations to store available activity information describing activities that are available for themselves. 
     The process shown in  FIG. 4  starts when companion electronic device  204  receives activity information describing an activity that is available at a second application at companion electronic device  204  (step  400 ), e.g., activity information describing activities that can be performed at companion electronic device  204 . Generally, this activity information describes an activity that can be performed in the second application at companion electronic device  204 , i.e., an operation or function that the second application at companion electronic device  204  is able to perform. In some embodiments, the second application reports/provides the activity information as the second application is installed and/or used. In some embodiments, companion electronic device  204  queries or otherwise monitors the second application to collect the activity information that describes the activity that is available at the second application. In some embodiments, the activity information includes activity information for activities that have not been performed on companion electronic device  204 , but that are available to be performed (e.g., activity information reported by the second application as the second application is installed/updated, launched, used, etc. at companion electronic device  204 ). 
     Next, companion electronic device  204  determines a second activity identifier, i.e., an activity identifier for the activity information that describes the activity that is available at the second application (step  402 ). Generally, the second activity identifier identifies the second application and the activity that is available at the second application. The second activity identifier can be an encoded representation of the activity information that describes the activity that is available at the second application. In some embodiments, companion electronic device  204  determines the second activity identifier by performing some or all of the same operations that source electronic device  202  performs to generate the activity identifier for the activity performed in the first application (see  FIG. 3 , step  306 ). For example, in some embodiments companion electronic device  204  uses the same hash function to generate the second activity identifier that source electronic device  202  uses to generate the activity identifier for the activity performed in the first application. 
     In some embodiments, when the second application can perform an activity that includes accessing a resource at a domain, the activity information for this activity includes a domain name for the domain. In some of these embodiments, the second activity identifier is an encoded representation of the domain name, which enables the second application to “claim” the domain name, i.e., to declare that the second application can use resources at the domain name so that companion electronic device  204  can transfer corresponding activities to the second application. For example, as will be described later, in a scenario where the second application streams movies from a specific site on the Internet, the second activity identifier can be an encoded representation of at least some part of the domain name for the site. Note that the second application can be different from the first application, i.e., the application whose activity is advertised in the activity advertisement message, enabling an application different from the first application to continue the activity at companion electronic device  204 . 
     Next, companion electronic device  204  stores the second activity identifier into the available-activity table (step  404 ). 
     Requesting Extended Activity Data and Transferring Activity 
     In some embodiments, upon receiving an activity advertisement message, an electronic device can request extended activity data for the advertised activity so that the advertised activity can subsequently be transferred to the electronic device.  FIG. 5  presents a flowchart illustrating a process for requesting extended activity data and transferring an activity in accordance with some embodiments. More specifically, during the process shown in  FIG. 5 , companion electronic device  204  requests, from source electronic device  202 , extended activity data for an activity performed in a first application in source electronic device  202 . Note that the operations shown in  FIG. 5  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., source electronic device  202 , companion electronic device  204 ), in some embodiments, other electronic devices and/or mechanisms perform the operations. 
     The process shown in  FIG. 5  starts when companion electronic device  204  receives an activity advertisement message (step  500 ), e.g., the activity advertisement message broadcast from source electronic device  202  (see  FIG. 3 , step  310 ). Next, companion electronic device  204  determines whether companion electronic device  204  is in a receptive state (step  502 ). Generally, companion electronic device  204  is in a receptive state when it is available for performing an activity transfer. For example, in some embodiments, companion electronic device  204  transitions to a receptive state when the device “wakes-up,” e.g., while displaying a lock screen after a user presses a button to wake-up the device. In some embodiments, companion electronic device  204  is not in a receptive state when companion electronic device  204  is in use, e.g., when a user is using an application at companion electronic device  204  and/or when the user has used an application within a given period of time. 
     If companion electronic device  204  is not in a receptive state (step  502 , no), the process ends (i.e., the activity advertisement message is ignored). Otherwise, if companion electronic device  204  is in a receptive state (step  502 , yes), companion electronic device  204  determines whether a second application that is associated with the first application is available at companion electronic device  204  (step  504 ). Generally, this operation includes determining if an application is available on companion electronic device  204  for continuing the activity described in the activity advertisement message from source electronic device  202 . Determining whether the second application is available is described in more detailed later with reference to  FIGS. 7-8 . 
     If the second application is not available (step  504 , no), the process ends. Otherwise, if the second application is available (step  504 , yes), companion electronic device  204  retrieves activity information for the second application (step  506 ). For example, as will also be described in more detail with reference to  FIGS. 7-8 and 11-12 , after determining the second application, companion electronic device  204  can use the activity identifier for the second application to retrieve activity information that describes the activity that is available in the second application from the available-activity table (or from another structure that companion electronic device  204  uses to store available activity information). In some embodiments, companion electronic device  204  uses the retrieved activity information, e.g., uses an application identifier in the retrieved activity information, to customize an indication that the activity is resumable, e.g., as described below with reference to step  508  and/or  FIG. 14 . Application identifiers are described in more detail with reference to  FIG. 11 . 
     Next, companion electronic device  204  presents an indication that the activity is resumable (step  508 ). For example, companion electronic device  204  can present a graphical icon and/or notification in a display of companion electronic device  204 . Indications are described in more detail below with reference to  FIG. 14 . 
     Then, companion electronic device  204  determines whether the activity transfer was accepted (step  510 ). In some embodiments, a user of companion electronic device  204  accepts and/or rejects the activity transfer by performing an action with the indication, such as clicking on the indication, dragging the indication in one or more directions and/or to one or more specific locations, etc. For example, to accept the activity transfer, a user can tap the icon/notification with a finger (on a touch screen display) and drag the icon/notification in a first direction (e.g., left to right, upward, clockwise in a circle, etc.). As another example, to reject an activity, a user can tap the icon/notification with a finger and drag the icon/notification in a second direction (e.g., right to left, downward, counterclockwise in a circle, etc.). In some embodiments, companion electronic device  204  determines that the activity transfer was not accepted based on a time-out period, i.e., by determining that a period of time has passed since the indication was presented without the user performing the action to accept the indication/activity transfer. 
     If the activity transfer is not accepted (step  510 , no), the process ends. Note that, in some embodiments, if the activity transfer is not accepted, companion electronic device  204  sends a message to source electronic device  202  to indicate that the activity transfer was not accepted. If the activity transfer is accepted (step  510 , yes), companion electronic device  204  sends a message to source electronic device  202  to request extended activity data for the activity performed in the first application (step  512 ). Generally, the request for extended activity data includes information to facilitate source electronic device  202  determining the activity for which the extended data is being requested. For example, in some embodiments companion electronic device  204  includes the activity identifier from the activity advertisement message with the request for extended activity data. 
     Next, upon receiving extended activity data from source electronic device  202  in response to the request for extended activity data, companion electronic device  204  configures the second application using the extended activity data (step  514 ). Configuring the second application can include launching/starting the second application, setting a state (or causing a change to the state) of the second application based on the extended activity data, and otherwise configuring the second application to perform a corresponding operation. For example, companion electronic device  204  can pass a document/resource identifier, information representing the document/resource, and/or a reference to the document/resource in the extended activity data to the second application to cause the second application access to the document/resource (e.g., an identifier for/information representing/a reference to a cloud-stored document for the second application to access from cloud-based storage located on the Internet, an identifier for/information representing/a reference to a document for the second application to access from a database, etc.). In some embodiments, when the activity includes composing a document that is stored at source electronic device  202 , the extended activity data includes the document or information representing the document, thereby enabling companion electronic device  204  and/or the second application to use/re-create the document at companion electronic device  204  for the second application. In some embodiments, the extended activity data includes edits in a document, e.g., the position and/or content of edits made in a document. In some embodiments, the extended activity data includes position information, such as the last played/viewed/recorded position in a media file (i.e, the position in the media file where playback or recording stopped or was last performed), the position of a marker in a file, the position/state of gameplay in a video game (e.g., the last level played, coordinates to a place that the player was last at, points and/or achievements earned, and/or information that can be used to recreate the state of a game played on source electronic device  202  at companion electronic device  204 ), etc. 
     Then, companion electronic device  204  commences performing the activity in the second application (step  516 ), which generally includes starting/launching the second application at companion electronic device  204  (if the second application was not already running) and executing the second application at companion electronic device  204  based on the extended activity data. For example, companion electronic device  204  can cause the second application to start executing in a viewing and/or editing mode for the document related to the advertised activity, and can cause the second application to scroll to the last position in the document that the document was viewed/edited at source electronic device  202 . Next, companion electronic device  204  sends a notification to source electronic device  202  indicating that the activity was transferred (step  518 ). 
     Note that some embodiments can use information in the activity advertisement message, e.g., the activity identifier, to start configuring the second application while the extended activity data is being transmitted, or even before the extended activity data is requested. Some of these embodiments use the information in the activity advertisement message to set an initial background for the second application, to set a mode for the second application (e.g., an editing mode, a read-only mode, an email composition mode, a note composition mode, etc.). Hence, some embodiments can launch and/or configure the second application before the extended activity data is received, possibly as soon as the activity transfer is accepted, thereby improving performance in slow networks by hiding data transfer time with application launch time. 
     In some embodiments, companion electronic device  204  sends the request for extended activity data using different signals than communication signals  208 , and/or by using a different communication channel/network interface than the one the activity advertisement message was received on. For example, companion electronic device  204  can receive the activity advertisement message over a Bluetooth link (using the BLE protocol) and can request the extended activity data over a Wi-Fi link or the Internet. In these embodiments, source electronic device  202  and companion electronic device  204  use communication signals  208 , e.g., the Bluetooth link, to exchange information that enables the electronic devices to communicate over the different communication channel/network. For example, in some of these embodiments, companion electronic device  204  creates a peer-to-peer network (e.g., an ad-hoc Wi-Fi network) and provides information to access the peer-to-peer network to source electronic device  202 . In some embodiments, source electronic device  202  provides the extended activity data to a server and companion electronic device  204  receives the extended activity data from the server, e.g., through the Internet. 
     Transitioning to a Receptive State Based on Advertising Information 
     Although in  FIG. 5  we describe embodiments that receive an activity advertisement message ( FIG. 5 , step  500 ) and determine whether companion electronic device  204  is in a receptive state ( FIG. 5 , step  502 ), some embodiments transition to a receptive state based on information in received activity advertisement messages. In some of these embodiments, after receiving an activity advertisement message (e.g., as shown in  FIG. 5 , step  500 ), companion electronic device  204  does not determine whether companion electronic device  204  is in a receptive state, i.e., the process shown in  FIG. 5  proceeds from step  500  to step  504  without performing operations for step  502 . 
     For example, in some embodiments, source electronic device  202  uses a low-power protocol such as Bluetooth low-energy (BLE), ZigBee, etc. to broadcast the activity advertisement message with corresponding communication signals  208 . Devices such as companion electronic device  204  may monitor for activity advertisement messages broadcast from source electronic device  202  using corresponding low-power mechanisms, such as a baseband processor within a corresponding network interface, e.g., a baseband processor in networking subsystem  106 . In some of these embodiments, the receiving of the activity advertisement message is handled by companion electronic device  204  using only a baseband processor for companion electronic device  204 , which means that companion electronic device  204  may otherwise be in an idle state (e.g., with subsystems such as the processing subsystem in a low-power state). For example, in some embodiments, companion electronic device  204  may be a smart phone in a user&#39;s pocket in an idle state in which a baseband processor monitors for activity advertisement messages while the processing subsystem (and companion electronic device  204  generally) is in a low-power state. 
     In some embodiments, upon recognizing the activity advertisement message as such, the baseband processor wakes the processing subsystem (and may generally transition companion electronic device  204  out of the idle operating state to a higher-power/more active operating state) to perform subsequent operations. For example, in some embodiments, companion electronic device  204  may monitor for activity advertisement messages and react to activity advertisement messages as is described in pending U.S. patent application Ser. No. 14/475,329, which was filed on 2 Sep. 2014, which is titled “Operating-Mode Transitions based on Advertising Information,” by inventors Craig P. Dooley, Akshay Mangalam Srivatsa, Anjali S. Sandesara, and Michael Giles, and which is incorporated by reference as described above. In some embodiments, companion electronic device  204 /the smart phone may not need to be retrieved from the user&#39;s pocket and activated to place companion electronic device  204  in a receptive state. 
     Responding to a Request for Extended Activity Data 
       FIG. 6  presents a flowchart illustrating a process for responding to a request for extended activity data in accordance with some embodiments. More specifically, during the process shown in  FIG. 6 , an electronic device such as source electronic device  202  responds to a request for extended activity data from an electronic device such as companion electronic device  204 . Note that the operations shown in  FIG. 6  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., source electronic device  202 , companion electronic device  204 ), in some embodiments, other electronic devices and/or mechanisms perform the operations. 
     The process shown in  FIG. 6  starts when source electronic device  202  receives a request for extended activity data (step  600 ), e.g., the request for extended activity data that companion electronic device  204  transmitted, as described with reference to step  512  in  FIG. 5 . 
     Next, source electronic device  202  uses information in the request for extended activity data to determine that the request is for extended activity data for the first application (step  602 ). For example, as described earlier, the request for extended activity data can include the activity identifier from the activity advertisement message (see step  308  in  FIG. 3 ). In some embodiments, source electronic device  202  performs a lookup for the activity identifier in the advertised-activity table (or other structure where advertised activity information is stored; examples of advertised-activity tables are described in more detail below with reference to  FIG. 12 ). When source electronic device  202  finds an entry in the advertised-activity table that includes the activity identifier from the activity advertisement message, source electronic device  202  can retrieve the activity information for the entry to determine that the activity identifier corresponds to the first application, e.g., by determining that the application identifier for the entry is the application identifier for the first application (examples of activity information and application identifiers are described in more detail with reference to  FIGS. 11-12 ). 
     Next, source electronic device  202  optionally sends a notification/request to the first application to perform an update related to the activity (step  604 ). In some embodiments, the notification causes the first application to update the extended activity data before providing the extended activity data to companion electronic device  204 . For example, the first application can use the notification to update the last scroll/viewed position for a document related to the activity and/or to perform finalizing operations related to the activity before the activity is transferred, such as saving a document related to the activity, updating the extended activity data with the latest draft of a document related to the activity, etc. 
     Then, source electronic device  202  retrieves the extended activity data for the first application (step  606 ). In some embodiments, source electronic device  202  requests that the first application provide the extended activity data. In some embodiments, the first application provides some or all of the extended activity along with the initial activity information (see  FIG. 3 , step  300 ) and/or periodically reports extended activity information (e.g., reports every N seconds, where N is a number such as 1, 3, etc., reports extended activity information each time an event happens for the first application, such as when a document is saved in the first application, a movie being watched is paused in the first application, etc.). 
     Next, source electronic device  202  sends the extended activity data to companion electronic device  204  (step  608 ). Generally, the extended activity data includes information that can be used to configure the second application to continue the activity, such as a document identifier that identifies a document used for the activity performed in the first application (and/or information representing the document, such as a reference to the document), a uniform resource location (URL) of web page accessed/browsed in the first application (and/or information representing the web page/URL, such as a reference to the web page/URL), position information (e.g., an indication of the last viewed/scrolled position in the document or the web page, the last played position in a video game, etc.), a copy of a draft document stored at source electronic device  202  and/or in a storage device accessible on the Internet (e.g., “cloud storage”) or a corporate network (and/or information representing the draft document, such as a reference to the draft document), etc. 
     Then, source electronic device  202  receives a notification that the activity was transferred (step  610 ), e.g., receives the notification sent by companion electronic device  204  as described with reference to  FIG. 5 , step  518 . In some embodiments, in response to receiving the notification, source electronic device  202  notifies the first application that the activity was transferred (step  612 ). In some embodiments, source electronic device  202  and/or the first application performs one or more operations related to the activity based on receiving the notification, e.g., housekeeping tasks such as deleting a locally-stored document/document draft, closing an open document, shutting down the application, etc. 
     In some embodiments, source electronic device  202  provides the extended activity data using different signals than communication signals  208 , and/or by using a different communication channel/network interface than the one the activity advertisement message and/or the request for extended activity data was communicated on. For example, source electronic device  202  can receive the request for extended activity data over a Bluetooth link and can provide the extended activity data over a Wi-Fi link or the Internet. 
     Secure Communication Using Cloud Pairing 
     As discussed earlier, in some embodiments, electronic devices that perform activity transfer operations participate in a preliminary pairing operation, e.g., a “cloud pairing” operation, such as the predefined pairing described in pending U.S. patent application Ser. No. 14/474,466, which is titled “Predefined Wireless Pairing,” by inventors Jason C. Conn, Akshay Mangalam Srivatsa, Craig P. Dooley, and Michael Giles, filed on 2 Sep. 2014, the contents of which are incorporated by reference as described above. In some embodiments, electronic devices encrypt and decrypt messages exchanged with each other for performing activity transfer operations using security information acquired during the cloud pairing operation, e.g., using encryption keys acquired during the cloud pairing operation. 
     For example, in some embodiments, source electronic device  202  encrypts the activity advertisement message (see  FIG. 3 , step  310 ) and/or the extended activity data (see  FIG. 6 , step  608 ) using an encryption key acquired during the cloud pairing operation that source electronic device  202  performs with companion electronic device  204 . In some embodiments, companion electronic device  204  encrypts the request for extended activity data (see  FIG. 5 , step  512 ) and/or the notification that the activity was transferred (see  FIG. 5 , step  518 ) using the same security information, different security information acquired during the cloud pairing operation that companion electronic device  204  performs with source electronic device  202 , and/or information derived from security information acquired during the cloud pairing operation. 
     Determining the Second Application Using an Activity Identifier 
     As described earlier, in some embodiments, an electronic device determines whether a second application that is associated with a first application is available in the electronic device (to facilitate a possible transfer of an activity to the electronic device).  FIG. 7  presents a flowchart illustrating a process for determining whether a second application is available at companion electronic device  204  in accordance with some embodiments. The operations shown in  FIG. 7  can be performed during the process shown in  FIG. 5 , e.g., at step  504 . Note that the operations shown in  FIG. 7  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., companion electronic device  204 , etc.), in some embodiments, other mechanisms perform the operations. For example, one or both of source electronic device  202  and second source electronic device  206  may perform similar operations to determine for themselves whether a second application is available. 
     The process shown in  FIG. 7  begins when companion electronic device  204  determines whether a flag in the activity advertisement message is asserted (step  700 ). As described earlier, in some embodiments, source electronic device  202  asserts a flag in the activity advertisement message to indicate that the activity identifier is/comprises a representation of a domain name for the advertised activity. In some of these embodiments, companion electronic device  204  determines that the activity advertisement message comprises a representation of a domain name by determining that the flag is asserted. Flags are described in more detail later in this description, e.g., with reference to  FIGS. 11 and 13 . 
     If a flag in the activity advertisement message is asserted (step  700 , yes), companion electronic device  204  processes the flag (step  702 ). The processing of the flag which takes place at step  702  is described later with reference to  FIG. 8 . Some embodiments repeat step  702  (i.e., the processing described with reference to  FIG. 8 ) for each asserted flag in the activity advertisement message, e.g., repeat the processing for each asserted flag when the activity advertisement message comprises two or more asserted flags. 
     If the activity advertisement message does not comprise a flag that is asserted (step  700 , no), companion electronic device  204  compares the activity identifier from the activity advertisement message to activity identifiers for activities that are available at companion electronic device  204  (step  704 ). For example, companion electronic device  204  can look up the activity identifier from the activity advertisement message in activity identifiers in the available-activity table at companion electronic device  204  (or other structure where companion electronic device  204  stores available activity information, as described earlier with reference to  FIG. 4 ). 
     If the lookup for the activity identifier finds a match in an entry in the available-activity table (step  706 , yes), companion electronic device  204  determines that the second application is the application whose activity identifier is stored in that entry (step  708 ). 
     If the lookup for the activity identifier does not find a match in the available activity information (step  706 , no), companion electronic device  204  determines that an application associated with the first application is not available at companion electronic device  204  (step  710 ). 
     Determining the Second Application Using a Flag 
     As described earlier, some embodiments assert a flag in the activity advertisement message.  FIG. 8  presents a flowchart illustrating a process for determining the second application using a flag in accordance with some embodiments. More specifically,  FIG. 8  presents a flowchart illustrating a process that companion electronic device  204  performs at step  702  of  FIG. 7 . Note that the operations shown in  FIG. 8  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., companion electronic device  204 , etc.), in some embodiments, other mechanisms perform the operations. For example, one or both of source electronic device  202  and second source electronic device  206  may perform similar operations for themselves. 
     The process shown in  FIG. 8  begins when companion electronic device  204  determines an application corresponding to the flag (step  800 ). In some embodiments, companion electronic device  204  uses the position of the asserted flag and/or the value of the flag to determine the application corresponding to the flag. For example, when the activity advertisement message includes more than one flag that can be asserted, each of the flags can be used to identify a different application that can be used to continue the activity. In some embodiments, the flag is a multi-bit field and different values of the multi-bit field identify a different application. In some embodiments, companion electronic device  204  stores a mapping that identifies the application that the position/value of the flags corresponds to. 
     Next, companion electronic device  204  determines whether the application corresponding to the flag is available at companion electronic device  204  (step  802 ). For example, companion electronic device  204  can check whether the application corresponding to the flag is installed at companion electronic device  204 . In some embodiments, step  802  is not performed/is skipped, so that the process shown in  FIG. 8  continues from step  800  to step  804 . For example, step  802  is not performed in embodiments that use flags to identify only pre-installed applications that are known to be available at companion electronic device  204  and cannot be uninstalled by a user. 
     If the application corresponding to the flag is available (step  802 , yes), companion electronic device  204  determines that the second application is the application corresponding to the flag (step  804 ). The process then ends, which can include continuing to step  506  in  FIG. 5 . 
     If the application corresponding to the flag is not available at companion electronic device  204  (step  802 , no), the process ends. At this point, companion electronic device  204  can determine that the second application is not available (e.g., as in  FIG. 5 , step  504 , no), or can continue to step  704  in  FIG. 7  to determine whether the second application is available by using the activity identifier from the activity advertisement message. 
     In some embodiments, the process shown in  FIG. 8  allows an application different than the first application to continue the activity at companion electronic device  204 . For example, consider the case where the first application is a web browser and the activity performed in the first application includes browsing a social-media website. In this example, the second application can be a social-media app that accesses resources (e.g., social media user pages, etc.) accessed in the first application/web browser (i.e., the second application is an app and not a web browser). By using the flag, these embodiments can configure the social-media app to continue the activity that was being performed at the social-media website, at the same point where the web browser left off. As another example, in some embodiments, the first application is a standalone media-streaming app that streams a movie from a website (such as a media player app) and the second application is a web browser than can stream the movie. By using the flag, these embodiments configure the web browser to continue playing the movie, which can include using the extended activity data for the activity to cause the web browser to continue playing the movie where the media-streaming app left off. 
     In some embodiments, source electronic device  202  sets a second flag (or a different value for the flag) in the activity advertisement message to indicate that source electronic device  202  will subsequently provide instructions/information on how to continue the activity at companion electronic device  204 . In some embodiments, the application corresponding to the flag comprises the instructions/information on how to continue the activity at companion electronic device  204 . In some embodiments, the extended activity data provides the instructions/information for continuing the activity at companion electronic device  204 . 
     Determining the Second Application Using a Structure Storing Advertised Activities 
     As described earlier with reference to  FIG. 3 , in some embodiments, the activity identifier in the activity advertisement message identifies an entry in a structure (e.g., a table) in which the electronic device that advertised the activity stores activity information for the advertised activity.  FIG. 9  presents a flowchart illustrating a process for determining whether the second application is available when the activity identifier identifies an entry in such a structure in accordance with some embodiments. More specifically, during the process shown in  FIG. 9 , companion electronic device  204  uses an activity identifier that identifies an entry in an advertised-activity table where source electronic device  202  stored activity information for the advertised activity to determine whether a second application that is associated with the first application is available at companion electronic device  204  (examples of advertised-activity tables are described in more detail below with reference to  FIG. 12 ). Note that the operations shown in  FIG. 9  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., source electronic device  202 , companion electronic device  204 ), in some embodiments, other electronic devices and/or mechanisms perform the operations. 
     The process shown in  FIG. 9  begins when companion electronic device  204  receives an activity identifier that identifies an entry in an advertised-activity table where source electronic device  202  stored activity information for the advertised activity (step  900 ). In some embodiments, the activity identifier includes a table identifier and an entry index, the table identifier identifying the advertised-activity table in which source electronic device  202  stored the activity information for the advertised activity, and the entry index identifying the entry in the advertised-activity table identified by the table identifier in which the activity information for the advertised activity is stored. In some embodiments, the table identifier is a hash of the advertised-activity table data. 
     Next, companion electronic device  204  determines whether the advertised-activity table for the activity identifier is available at companion electronic device  204  (step  902 ). In some embodiments, companion electronic device  204  uses the table identifier from the activity identifier to determine whether companion electronic device  204  has stored a local copy of the advertised-activity table. 
     If the advertised-activity table for the activity identifier is not available at companion electronic device  204  (step  902 , no), companion electronic device  204  retrieves the advertised-activity table from source electronic device  202  (step  904 ). In some embodiments, companion electronic device  204  requests that source electronic device  202  send the advertised-activity table identified by the activity identifier from the activity advertisement message, e.g., the advertised-activity table identifier by the table identifier. Companion electronic device  204  can transmit such a request, and source electronic device  202  can respond to the request, using communication signals  208  and/or a different communication signals/a different channel. 
     In some embodiments, companion electronic device  204  periodically synchronizes its local copy/copies of advertised-activity tables with source electronic device  202 . For example, companion electronic device  204  may receive a copy of an advertised-activity table from source electronic device  202  using a “push” mechanism, i.e., without sending a request for the copy of the advertised-activity table. 
     If the advertised-activity table for the activity identifier is available at companion electronic device  204  (step  902 , yes), or after receiving the advertised-activity table from source electronic device  202 , companion electronic device  204  uses the activity identifier to retrieve the activity information from the advertised-activity table (step  906 ). For example, companion electronic device  204  can retrieve the activity information from the entry in the advertised-activity table that is identified by the entry index. 
     In some embodiments, the operations shown in  FIG. 9  enable information describing more than one activity to be advertised in a single activity advertisement message. For example, consider the case where the size of the activity advertisement message is limited, e.g., because of limitations of a network protocol used to broadcast the activity advertisement message. In this case, an entry identifier, i.e., an activity identifier that identifies an entry where activity information is stored, can be smaller (e.g., represented using fewer bits than the activity identifier) than an encoded representation, i.e., an activity identifier generated from the same activity information, enabling these embodiments to carry multiple entry identifiers in an activity advertisement message. 
     As described earlier with reference to  FIG. 3 , the described embodiments are not limited to using a table for storing the available activity information. Some embodiments use a different structure for storing the available activity information, such as an associative array, a content-addressable memory, etc. In these embodiments, the activity identifier can identify an entry in a structure in which source electronic device  202  stores activity information for the advertised activities. For example, in these embodiments, the table identifier can identify the structure and the entry index can identify the index in the structure where source electronic device  202  stored the activity information for the advertised activity. 
     Also, although we describe embodiments that use one advertised-activity table, some embodiments use more than one advertised-activity table, e.g., store activity information for advertised activities in different advertised-activity tables. 
     Determining a Most Recent Activity 
     As described earlier, network environment  200  can include a second source electronic device, which can broadcast activity advertisement messages for activities performed at the second source electronic device. As was also described earlier, some embodiments include a timestamp in an activity advertisement message to indicate the time that the activity advertised in the activity advertisement message was last performed.  FIG. 10  presents a flowchart illustrating a process for determining a most recent activity from two or more activity advertisement messages in accordance with some embodiments. More specifically, during the process shown in  FIG. 10 , companion electronic device  204  uses a timestamp included with the advertisement from source electronic device  202  (“activity advertisement”) and a timestamp included an advertisement from second source electronic device  206  (“second activity advertisement”) to determine the most recent of the activities advertised in the activity advertisement and the second activity advertisement. Note that the operations shown in  FIG. 10  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., source electronic device  202 , companion electronic device  204 , second source electronic device  206 ), in some embodiments, other electronic devices and/or mechanisms perform the operations. 
     For the process shown in  FIG. 10 , it is assumed that companion electronic device  204  has already received the activity advertisement from source electronic device  202 , e.g., as shown in  FIG. 5 . Therefore, companion electronic device  204  has the activity advertisement, including a first timestamp included with the activity advertisement. 
     The process shown in  FIG. 10  begins when companion electronic device  204  receives the second activity advertisement (step  1000 ). Next, companion electronic device  204  compares the first timestamp included with the activity advertisement with a second timestamp included with the second activity advertisement (step  1002 ). For example, companion electronic device  204  can compare the timestamps to see which one is newer (i.e., indicates a more recent time). 
     If the comparison indicates that the first timestamp is newer (step  1004 , yes), companion electronic device determines that the activity performed in the first application, i.e., the activity advertised in the activity advertisement, is the most recent activity (step  1006 ). Otherwise, if the comparison indicates that the second timestamp is newer (step  1004 , no), companion electronic device  204  determines that the activity performed in the second application, i.e., the activity advertised in the second activity advertisement, is the most recent activity (step  1008 ). 
     In some embodiments, companion electronic device  204  reduces the number of indications that are presented to a user in a display of companion electronic device  204  (e.g., as shown in  FIG. 14 ) by only presenting an indication that an activity is resumable for the most recent of the advertised activities. In some embodiments, companion electronic device  204  uses timestamps to present the indications that activities are resumable in order, e.g., to present the most recent activity first, followed by other advertised activities in descending order based on relative recentness. In these embodiments, two or more indications can be presented side-by-side, one above the other, etc. in accordance with the relative recentness of the corresponding activities. 
     In some embodiments, companion electronic device  204  uses a history of activities that have previously been continued to present indications for activities that are resumable in order. In some embodiments, companion electronic device  204  ranks activities that have previously been continued higher in order, i.e., presents an indication that an activity that has previously been continued is resumable ahead of an indication that an activity that has not previously been continued is resumable. In some embodiments, two or more indications are presented in order based on a number of times that each of the corresponding activities have previously been continued. 
     Dynamic Type Information 
     As described earlier, some embodiments use activity information that describes an activity performed at an electronic device. In some embodiments, the activity information includes dynamic type information, which generally comprises data (e.g., a string) provided by the first application as it is executing. Dynamic type information can describe an attribute of an activity performed at the first application and can enable the first application to provide conditions under which the first application can be transferred to another electronic device. As will be described later with reference to  FIG. 12 , activity information that includes dynamic type information can be based on a dynamic-type descriptor, whereas other activity information can be based on an activity descriptor. 
     In some embodiments, activity descriptors differ from dynamic-type descriptor in that activity descriptors are static, whereas dynamic-type descriptors can be dynamically changed by an application at runtime. For example, source electronic device  202  can receive an activity descriptor when a first application is installed and can store activity information based on the activity descriptor persistently (e.g., at an available-activity table) so that it does not change unless the application is removed and/or re-installed. For example, when an e-mail application is installed, it can provide activity descriptors indicating that it can read and compose e-mail messages. As another example, when a media player application is installed it may provide activity descriptors to indicate it is able to play back media files. 
     In the same example, source electronic device  202  can receive the dynamic-type descriptor when the first application starts, or while the application is executing. For example, while an email application is executing, it may provide a dynamic-type descriptor that describes e-mail accounts that the application has access to. The email application mat provide new dynamic type information (or update existing information) as the user adds or removes email accounts from the application. As another example, a media player application may provide dynamic-type descriptors to specify the types of devices that the media can be played back on. In some embodiments, source electronic device  202  stores dynamic-type information based on the dynamic-type descriptor separately from activity information (e.g., in an available-dynamic-type table which is separate from the available-activity table). In some embodiments, dynamic type information stored in the available-dynamic-type table does not persist (is deleted) when an application exits. Generally, the first application can update activity information based on dynamic type descriptors as needed, whereas activity information based on activity descriptors remains unchanged at source electronic device  202  until the application is re-installed. 
     Some embodiments handle the dynamic type information similar to how activity information is handled. For example, source electronic device  202  can perform the process shown in  FIG. 3  for dynamic type information (instead of activity information) in addition to (or instead of) performing it for activity information, thereby generating a dynamic type identifier using the same process used to generate an activity identifier (e.g., a hash function, which can be the same or different from the hash function used to generate the activity identifier). Similarly, the processes shown in  FIGS. 4-6 and 8-10  can be performed for dynamic type information. 
       FIG. 18B  presents an example of operations performed by source electronic device  202  and companion electronic device  204  when performing activity continuation using dynamic type information in accordance with some embodiments. To better illustrate differences between embodiments that use dynamic type information and those that do not,  FIG. 18A  is presented as an example of operations performed by source electronic device  202  and companion electronic device  204  when performing activity continuation without using dynamic type information in accordance with some embodiments. The operations shown in  FIGS. 18A-B  for source electronic device  202  can be performed during the process shown in  FIG. 3 , and the operations shown in  FIGS. 18A-B  for companion electronic device  204  can be performed during the process shown in  FIG. 5 . Note that the operations shown in  FIGS. 18A-B  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., source electronic device  202 , companion electronic device  204 , etc.), in some embodiments, other mechanisms perform the operations. For example, second source electronic device  206  may perform similar operations to determine for itself whether a second application is available. 
     Considering first the example shown in  FIG. 18A  (which does not use dynamic type information), source electronic device  202  receives activity information A 1  (step  1800 ), which includes an activity descriptor, e.g., the string “com.apple.Mail:Read.” In this example, the activity information indicates that the application used to perform the activity is the Mail application, and the activity involves reading e-mail. Source electronic device  202  can receive the activity information A 1  any time the Mail application is used. In some embodiments, source electronic device  202  receives activity information A 1  when application Mail starts or is accessed. In some embodiments, source electronic device  202  receives activity information A 1  when application Mail is installed and/or setup. In some embodiments, source electronic device  202  does not permit changes to activity information A 1  after application Mail is installed until the application is re-installed, re-configured, and/or re-started. 
     Next, source electronic device  202  receives an identifier B 1 , which includes the string “00” (step  1802 ). Identifier B 1  can include any data, e.g., can be an application identifier. In some embodiments, identifier B 1  is a bundle identifier or team identifier that identifies the developer of application Mail. Note that step  1802  is optional—some embodiments do not use an identifier B 1 . 
     Then, source electronic device  202  generates an activity identifier, which is the output of a hash function HASH of A 1  and B 1  (step  1804 ), e.g., a hash of strings “com.apple.Mail:Read” and “00.” Source electronic device  202  broadcasts an activity advertisement message that includes H 1  (step  1806 ). 
     Looking now at companion electronic device  204 , at some point in time (which can be a point in time before step  1800  is performed, while step  1800  is being performed, or after step  1800  is performed), similar to steps  1800 - 1802  for source electronic device  202 , companion electronic device  204  receives activity information E 1  (step  1810 ) and identifier F 1  (step  1812 ) for an activity that can be performed using the Mail application at companion electronic device  204 . Because the operations performed at companion electronic device  204  at steps  1810 - 1812  are similar to operations performed at source electronic device at steps  1800 - 1802 , respectively, the description of these operations is not repeated here. 
     Next, companion electronic device  204  generates an available-activity identifier for the activity performed with application Mail (step  1814 ), which involves applying the same hash function used at step  1804  to E 1  and F 1 . Companion electronic device  204  stores the activity identifier in an available-activity table (step  1816 ). Next, companion electronic device  204  receives the activity advertisement broadcast at step  1806  (step  1818 ). Then, companion electronic device  204  processes the received advertisement (step  1820 ), which can involve companion electronic device  204  performing operations similar to those shown in  FIG. 5 . In this example, companion electronic device will find a match for H 1  (from the activity advertisement) in the entry in the available-activity table that stores H 2 , and may display an indication that the activity can be transferred. 
     Considering now the example shown in  FIG. 18B  (which uses dynamic type information), similar to steps  1800  and  1802  in  FIG. 18A , at steps  1850  and  1854 , respectively, source electronic device  202  receives activity information A 1  and identifier B 1 . Because the operations performed at source electronic device  202  at steps  1850  and  1854  are similar to operations performed at source electronic device at steps  1800 - 1802 , respectively, the description of these operations is not repeated here. 
     At some point in time, source electronic device  202  receives dynamic type information C 1 , e.g. a dynamic identifier, which includes the string “bob@apple.com” (step  1852 ). Application Mail can provide dynamic type information C 1  at any point, including while the user is using the application, when the user makes a configuration change, e.g., when the user adds the email account “bob @ apple.com” to the Mail application, and/or each time a user opens an email message for that account. 
     Then, source electronic device  202  generates an activity identifier H 3 , i.e., a hash of A 1 , B 1 , and C 1  (step  1856 ). Therefore, hash H 3  includes dynamic type information that describes an activity being performed in an application, e.g., Mail, at source electronic device  202 . Next, source electronic device  202  broadcasts an activity advertisement with that includes H 3  (step  1858 ). Because the activity advertisement includes H 3 , which is derived based on dynamic type information, the activity advertisement message comprises dynamic type information describing an attribute of an activity being performed in the Mail application at the source electronic device  202 . 
     Looking now at companion electronic device  204 , at steps  1860  and  1864 , companion electronic device  204  performs operations similar to those for steps  1810 - 1812  (see  FIG. 18A ), respectively. Because the operations performed at companion electronic device  204  at steps  1860  and  1864  are similar to operations performed at steps  1810 - 1812 , respectively, the description of these operations is not repeated here. 
     At some point in time, companion electronic device  204  receives dynamic type information G 1  and G 2  (step  1862 ), which include strings “bob@apple.com” and “bob@me.com,” e.g., two separate e-mail addresses that application Mail can access at companion electronic device  204 . Companion electronic device  204  can receive G 1  and G 2  at the same time or separately. For example, application Mail can provide G 1  and/or G 2  to companion electronic device  204  when a user adds each account to a list of accounts that Mail can access, or each time a user accesses an account to read and/or compose an email message, or a third party such as an account provider can communicate this information to companion electronic device  204 . 
     Next, companion electronic device  204  generates two activity identifier, which includes hashes H 4 =HASH(E 1 , F 1 , G 2 ) and H 5 =HASH(E 1 , F 1 , G 2 ) (step  1866 ). Companion electronic device  204  stores H 4  and H 5  in an available-dynamic-type table (step  1868 ), indicating that application Mail can continue activities for those dynamic types. 
     Next, companion electronic device  204  receives the activity advertisement broadcast at step  1858  (step  1870 ). Then, companion electronic device  204  processes the received activity advertisement (step  1872 ), which can involve, which can involve companion electronic device  204  performing operations similar to those shown in  FIG. 11 . In this example, companion electronic device  204  will find a match for H 3  (from the activity advertisement) in the entry in the available-dynamic-type table that stores H 4 , and may display an indication that the activity can be transferred. In some embodiments, however, if companion electronic device  204  does not find a match for the hash, companion electronic device  204  does not display the indication that activity can be transferred. 
     Note that some embodiments perform operations for broadcasting activity advertisements both without and with dynamic type information. For example, in some embodiments source electronic device  202  performs some or all of operations  1800 - 1806  and  1850 - 1858 . Some of these embodiments broadcast both types of activity advertisements to ensure backwards compatibility embodiments that do not use dynamic-type-information. 
     Determining Second Application Using Dynamic Type Information 
     As described earlier, in some embodiments, an electronic device determines whether a second application that is associated with a first application is available in the electronic device (to facilitate a possible transfer of an activity to the electronic device).  FIG. 11  presents a flowchart illustrating a process for determining whether a second application is available at companion electronic device  204  when the above-described dynamic type information is used in accordance with some embodiments. The operations shown in  FIG. 11  can be performed during the process shown in  FIG. 5 , e.g., at step  504 . Note that the operations shown in  FIG. 11  are presented as a general example of operations performed by some embodiments. The operations performed by some embodiments include different operations and/or operations that are performed in a different order. Additionally, although certain mechanisms are used in describing the operations (e.g., companion electronic device  204 , etc.), in some embodiments, other mechanisms perform the operations. For example, one or both of source electronic device  202  and second source electronic device  206  may perform similar operations to determine for themselves whether a second application is available. 
     The process shown in  FIG. 11  begins when companion electronic device  204  receives an activity advertisement message that includes an identifier for an activity performed in a first application, e.g., a first application executing at source electronic device  202  (step  1100 ). The received identifier can include/be generated from an activity descriptor and/or a dynamic type identifier, examples of which as shown in  FIG. 12 . 
     If the flag in the activity advertisement message is asserted (step  1102 , yes), companion electronic device  204  processes the flag (step  1104 ). The processing of the flag which takes place at step  1104  was described earlier with reference to  FIG. 8 . Some embodiments repeat step  1104  (i.e., the processing described with reference to  FIG. 8 ) for each asserted flag in the activity advertisement message, e.g., repeat the processing for each asserted flag when the activity advertisement message comprises two or more asserted flags. 
     If the activity advertisement messages do not comprise an asserted flag (step  1102 , no), companion electronic device  204  compares the received identifier with a set of dynamic type identifiers for activities that are available at companion electronic device  204  (step  1106 ). For example, companion electronic device  204  can look up the received identifier in the available-dynamic-type table at companion electronic device  204  (or other structure where companion electronic device  204  stores available dynamic type information). 
     If the lookup for the received identifier finds a match in an entry in the available-dynamic-type table (step  1108 , yes), companion electronic device  204  determines that the second application is the application whose dynamic type identifier is stored in that entry (step  1110 ). 
     If the lookup for the received identifier does not find a match in the available-dynamic-type table (step  1108 , no), companion electronic device  204  compares the received identifier with a set of activity identifiers for activities that are available at companion electronic device  204  (step  1112 ). For example, companion electronic device  204  can look up the received identifier in the available-activity table at companion electronic device  204  (or other structure where companion electronic device  204  stores available dynamic type information). 
     If the lookup for the received identifier finds a match in an entry in the available-activity table (step  1114 , yes), companion electronic device  204  determines that the second application is the application whose activity identifier is stored in that entry (step  1116 ). 
     If the lookup for the received identifier does not find a match in the available-activity table (step  1114 , no), companion electronic device  204  determines that an application associated with the first application (e.g., an application that can continue the activity performed with the first application) is not available at companion electronic device  204  (step  1118 ). 
     Activity Information 
     As described earlier, some embodiments use activity information that describes an activity performed at an electronic device.  FIG. 12  presents a block diagram illustrating activity information  1100 - 1140  in accordance with some embodiments. Note that activity information  1100 - 1140  shown in  FIG. 12  are presented as a general example of formats of activity information used by some embodiments. Some embodiments use a different format and/or include different information in activity information. 
     Activity information  1200  includes application identifier  1202 , which identifies the application used to perform the activity described in activity information  1200 . For example, application identifier  1202 , which includes the string com.apple.Keynote, identifies application Keynote, an application that can be used to edit and view presentations. Activity descriptor  1204  includes the string EditPresentation, which identifies the activity performed with application Keynote as editing a presentation. Timestamp  1206 , which includes the string/number  103 , identifies a time that the activity was last performed, for example, the last time that a user edited the presentation in application Keynote. The timestamp can indicate a real time, e.g., the wall-clock time (or a representation thereof, such as a system time) when the activity was last performed, or it can be a representation of time elapsed since the activity was last performed after the top of the hour, or since a synchronization event. In some embodiments, the timestamp indicates a real time, e.g., the absolute/wall-clock time (or a representation thereof, such as a system time) when source electronic device  202  was last used (e.g., last used actively by a user), or it can be a representation of time elapsed since source electronic device  202  was last used after the top of the hour, or since a synchronization event. In activity information  1200 , flag  1208  is not asserted. 
     Activity information  1210  includes application identifier  1212 , which identifies the application used to perform the activity described in activity information  1210 . For example, application identifier  1212 , which includes the string com.apple.Mail, identifies application Mail, an application that can be used to compose and send e-mail messages. Activity descriptor  1214  includes the string ComposeDraft to identify that the activity performed with application Mail includes composing a message draft. Timestamp  1216 , which includes string/number  315 , identifies a time that the activity was last performed, for example, the last time that the user used Mail to compose the draft. Flag  1218  for activity information  1210  is not asserted. 
     Activity information  1220  includes application identifier  1222 , which identifies the application used to perform the activity described in activity information  1220 . For example, application identifier  1222 , which includes the string com.apple.Safari, identifies application Safari, a web browser. Activity descriptor  1224  includes the string www.evideostreamer.com, which identifies a domain name accessed with the web browser. In this example, activity descriptor  1224  holds a domain name, so flag  1228  in activity information  1220  is asserted flag  1228  to indicate that activity description  1224  comprises a domain name. Timestamp  1226 , which includes string/number  820 , identifies a time that the web browser was last used to access the move-streaming website. 
     Activity information  1230  includes application identifier  1232 , which identifies the application used to perform the activity described in activity information  1230 . For example, application identifier  1232 , which includes the string com.CompanyA.MediaPlayer, identifies application MediaPlayer (which in this example is developed by developer CompanyA), an application that can be used to play and record multimedia content. Activity descriptor  1234  includes the string PlayVideo to identify that the activity performed with application MediaPlayer includes playing a video, i.e., video playback. Timestamp  1236 , which includes string/number  902 , identifies a time that the activity was last performed, for example, the last time that the user used MediaPlayer to play the video. Flag  1238  for activity information  1230  is not asserted. 
     Activity information  1230  includes application identifier  1232 , which identifies application Mail, and activity descriptor  1234 , which describes that the activity involves reading mail. Dynamic type descriptor  1236  describes an attribute of the activity, i.e., an email account from which mail can be read. In this example, application Mail can use the dynamic type descriptor  1236  to indicate e-mail accounts to which it has access. Timestamp  1238  identifies a time that mail was last read. 
     Activity information  1240  includes application identifier  1242 , which identifies MediaPlayer as the application which is used to perform the activity. Dynamic type descriptor  1244 , which includes the string TV, is used to indicate that the activity can be continued on a television. Timestamp  1238  identifies a time that MediaPlayer was last used. 
     For illustrative purposes, the timestamps shown in  FIG. 11  are calculated as a delta (difference) from a synchronization event, e.g., the top of the hour. Hence, in the examples shown in  FIG. 11 , the activity described with activity information  1200  is the most recent activity, because timestamp  1206  indicates that the least amount of time has elapsed from the top of the hour since the activity described with activity information  1200  was performed. 
     Note that, although the examples shown in  FIG. 12  use strings for the application identifier, the activity descriptor, and the dynamic type descriptor, some embodiments may use different information to identify the application and/or the activity. For example, some embodiments use a numerical identifier for the application identifier and/or the activity descriptor. In some embodiments, the application identifier is an identifier for the corresponding application in an online “app store.” In some embodiments, the application identifier comprises some or all of a bundle identifier, e.g., a bundle ID. Also, although the application identifier shown is separate from the activity descriptor, some embodiments combine the application identifier and the activity descriptor in a single identifier. 
     In some embodiments, application/app developers provide the information for the activity and/or dynamic type descriptors, such as activity descriptor  1204 ,  1214 ,  1224 , and  1234 , and/or dynamic type descriptors  1236  and/or  1234 . In these embodiments, the developer of an application/app may determine a number of activities for the application/app and may provide relevant values for activity and/or dynamic descriptors. 
     Advertised-Activity Table 
       FIG. 13  presents a block diagram illustrating an advertised-activity table  1300  in accordance with some embodiments. As described above, advertised-activity table  1300  includes information about activities that have been advertised (i.e., activities for which an activity advertisement message has been sent by an electronic device such as source electronic device  202 ). Note that the advertised-activity table shown in  FIG. 13  is presented as a general example of advertised-activity tables used by some embodiments. Some embodiments represent activity information differently and/or include more or less information in the advertised-activity table. 
     Entry  1302 , which is identified by entry index  1306 , stores activity information  1300  and activity identifier  1304 . In this example, activity identifier  1304  is generated using application identifier  1202  and activity descriptor  1204 , such as a hash of string “com.apple.Keynote::EditPresentation.” 
     Entry  1312 , which is identified by entry index  1316 , stores activity information  1210  and activity identifier  1314 . In this example, activity identifier  1314  is generated using application identifier  1212  and activity descriptor  1214 , such as a hash of string “com.apple.Mail::ComposeDraft.” 
     Entry  1322 , which is identified by entry index  1326 , stores activity information  1220  and activity identifier  1324 . In this example, activity identifier  1324  is generated using activity descriptor  1224 , such as a hash of string www.evideostreamer.com. 
     Entry  1332 , which is identified by entry index  1336 , stores activity information  1230  and activity identifier  1334 . In this example, activity identifier  1334  is generated using application identifier  1202 , activity descriptor  1234 , and dynamic type descriptor  1236 , such as a hash of the string “com.apple.Mail:Read:bob@apple.com.” Note that, because activity identifier  1334  includes dynamic type information, activity identifier  1334  can also be referred to a dynamic type identifier (i.e., the terms can be used interchangeably when the activity information includes dynamic type information). 
     Entry  1342 , which is identified by entry index  1346 , stores activity information  1240  and activity identifier  1344 . In this example, activity/dynamic type identifier  1344  is generated using application identifier  1242  and dynamic type descriptor  1244 , such as a hash of the string “com.comA.MediaPlayer:TV.” The first application can use the dynamic type information string “TV” to indicate that the activity can be continued on a television set. 
     For illustrative purposes, entries  1302 - 1342  store all of activity information  1200 - 1430 , respectively. Note though that, in some embodiments, entries  1302 - 1342  store only some of activity information  1200 - 1240 , respectively. For example, some embodiments do not store timestamps  1206 - 1246  in entries  1302 - 1342 . 
     Available-Activity Table 
     In some embodiments, the above-described available-activity table is formatted similarly to advertised-activity table  1300  shown in  FIG. 13 . However, the entries in the available-activity table include application information for applications that are available in the corresponding electronic device, e.g., companion electronic device  204 . 
     Available-Dynamic-Type Table 
     In some embodiments, the above-described available-dynamic-type table is formatted similarly to advertised-activity table  1300  shown in  FIG. 13 . However, the entries in the available-dynamic-type table include dynamic type information for applications that are available in the corresponding electronic device, e.g., companion electronic device  204 . 
     In some embodiments, the available-activity table and available-dynamic-type table are combined at companion electronic device  204  to a single table/structure. 
     Activity Advertisement Message 
       FIG. 14  presents a block diagram illustrating an activity advertisement  1400 , e.g., an activity advertisement message, in accordance with some embodiments. Note that the activity advertisement message shown in  FIG. 14  is presented as a general example of an activity advertisement message used by some embodiments. Some embodiments order fields in the activity advertisement message differently and/or include different information in the activity advertisement message. 
     Activity advertisement message  1400  optionally includes device ID field  1402  and version ID field  1404 . Device ID field  1402  includes an identifier that identifies the device from which activity advertisement message  1400  was sent, e.g. identifies source electronic device  202 . Version ID field  1404  includes a version identifier, such as a version identifier that companion electronic device  204  can use to determine how fields in activity information  1400  are formatted and/or how information is stored in the fields. 
     Activity identifier field  1406  includes an activity identifier, e.g., one or more of activity identifiers  1304 - 1344 . Flags field  1408  includes one or more flags corresponding to the advertised activity, e.g., flag  1208 - 1228 . 
     Timestamp field  1410  includes a timestamp for an activity advertised in activity identifier field  1406 , e.g., one or more of timestamps  1206 - 1226 . 
     Resumable-Activity Indication 
     As described earlier, some embodiments present an indication that the activity is resumable before requesting the extended activity data.  FIG. 15  presents a block diagram illustrating a resumable-activity indication, i.e., an indication that an activity is resumable, in accordance with some embodiments. More specifically,  FIG. 15  shows a resumable-activity indication displayed on display  1500  for companion electronic device  204 . Note that the resumable-activity indication shown in  FIG. 15  is presented as a general example of a resumable-activity indication used by some embodiments. Some embodiments use a different resumable-activity indication and/or present the resumable-activity indication differently. 
     In the illustrated embodiment, companion electronic device  204  is a smartphone that comprises a touch-screen display  1500 . The embodiment shown in  FIG. 15  is in a receptive state because display  1500  shows a lock screen with unlock indicator  1502 , which shows the phrase “slide to unlock.” Generally, a user of companion electronic device  204  performs an operation with unlock indicator  1502  to unlock companion electronic device  204 , such as sliding a graphic for unlock indicator  1502  across display  1500  with a finger. 
     Resumable-activity indication  1504  comprises a graphic, e.g., an icon, that a user can manipulate to accept (or reject) the activity transfer. In  FIG. 15 , resumable-activity indication  1504  comprises an icon resembling an envelope, indicating that the resumable activity includes using a mail application. In some embodiments the user can accept the activity transfer by clicking on/touching resumable-activity indication  1504 , and/or by moving resumable-activity indication  1504  along one or more paths on display  1500 . For example, in some embodiments the user can accept the activity transfer by touching and dragging resumable-activity indication  1504  along or near path  1506  (shown as a dotted line). 
     For illustrative purposes, resumable-activity indication  1504  is shown at a lock screen for companion electronic device  204 . In some embodiments, resumable-activity indication  1504  can be shown at a different screen/location, e.g., at an unlocked screen, at a menu bar, by using a notification window/pop-up, etc. Also, the position, size, graphic, color and/or other visual features of resumable-activity indication  1504  can vary for different embodiments, and can depend on the type of activity that can be resumed. For example, in some embodiments companion electronic device  204  determines the graphic shown in resumable activity indication  1504  based on the application identifier for the advertised activity. As another example, in some embodiments resumable-activity indication  1504  is shown at the lower left corner of display  1500 . Some embodiments present multiple resumable-activity indicators at the same time. 
     Note that accepting (or rejecting) the activity transfer can include moving resumable-activity indication  1504  along a different path than path  1506 , e.g., to the top of the screen, along a curved path, etc. In some embodiments, the user can accept the activity transfer by performing one or more of: clicking on resumable-activity indication  1504 , tapping on resumable-activity indication  1504 , swiping resumable-activity indication  1504 , or performing a gesture using resumable-activity indication  1504 . 
     Applications of Dynamic Type Information 
     As described earlier, some embodiments use dynamic type information to enable the first application to provide conditions under which the first application can be transferred to another electronic device. Examples of dynamic type information (e.g., information that, for the purposes of this description, is treated/processed like activity information was described above with reference to  FIGS. 12-13 ). An application can use dynamic type information to control when an activity can be transferred to another device, which can prevent presenting a resumable activity indication for an activity. 
     For example, consider the case where a user uses the iTunes media player to play a song that was purchased using a first account (iTunes is a trademark of Apple Inc. of Cupertino, Calif.). iTunes can provide a dynamic type descriptor to indicate that the activity of playing the song can be continued only on devices that have access to that account. For example, with reference to  FIG. 12 , iTunes can provide dynamic descriptor  1236  to cause an advertisement that includes the dynamic type information in dynamic descriptor  1236  to be broadcast. In this example, only companion electronic devices that have access to that account (i.e., that have created an activity identifier that matches the one broadcast for iTunes) can continue the activity. 
     As another example, consider an application that allows activities involving phone calls or text messages to be continued on a computer. The phone&#39;s user may want these activities to be continued on a personal laptop, but not on a shared desktop computer. In this example, a first application (e.g., an application that is used to make phone calls and/or send/receive text messages) can provide dynamic type descriptors that identify the devices owned by the user to which the activities continued, thereby preventing other devices from displaying a resumable activity indicator for an activity they can otherwise continue. 
     As another example, consider activity information  1240  in  FIG. 12 . In this example, an application can provide dynamic type descriptor  1244  to indicate that the activity performed in the application can be continued only on certain types of devices. For example, the user may be using a device to watch a movie but does not want resumable activity indicators for watching movies shown to a phone or watch. By providing a dynamic descriptor identifying the types of devices that an activity can be continued on (e.g., a tablet or a television (TV)), other devices will not unnecessarily display a resumable activity indicator. 
     Hence, by using dynamic type information, embodiments of the present invention can prevent resumable activity indicators from being displayed on devices where an activity cannot (or is not desired to be) continued). 
     Automatic and Manual Activity Advertisement 
     In some embodiments, source electronic device  202  broadcasts activity advertisements automatically, e.g., at predetermined time intervals, as soon as activity information is received, based on a detected location of source electronic device  202 , etc. In these embodiments, source electronic device  202  can provide a setting, e.g., a system preference, which a user can use to turn the broadcasting of activity advertisements on or off. 
     In some embodiments, source electronic device  202  starts broadcasting activity advertisements manually, i.e., waits for input from a user to begin broadcasting the activity advertisements. In some of these embodiments, source electronic device  202  starts broadcasting activity advertisements upon detecting the user&#39;s input, and continues to broadcast activity advertisements for a predetermined period of time and/or until the user provides an input directing source electronic device  202  to stop the activity advertisements. In some embodiments, the user input for starting and/or stopping activity advertisements includes motion of source electronic device  202  (e.g., shaking source electronic device  202 , moving source electronic device  202  in an arc, rocking source electronic device  202 , etc.), performing one or more gestures on a touch screen for source electronic device  202 , pressing a key and/or button combination, etc. 
     In some embodiments, the activity advertisement message and/or a message that source electronic device  202  sends to companion electronic device  204  along with (i.e., in addition to) the activity advertisement message causes companion electronic device  204  to start a timer. In some embodiments, companion electronic device  204  remains in the receptive state as described above until this timer expires. Source electronic device  202  can provide an expiry time for the timer to companion electronic device  204 , or companion electronic device  204  can determine the expiry time. 
     In some embodiments, companion electronic device  204  presents an indication that the activity is resumable until the timer expires, and, if the user accepts the indication, continues the activity at companion electronic device  204  without the user performing one or more operations (e.g., fingerprint scan, password entry, etc.) to unlock companion electronic device  204 . More specifically, companion electronic device  204  can detect that the user accepted the indication and can bypass the lock screen/unlock operation, allowing the user to start using companion electronic device  204  without unlocking companion electronic device  204 . In some embodiments, the user is allowed to bypass the lock screen/unlock operation only before the timer expires. 
     Activity Continuation Framework 
     In some embodiments, a third-party application receives access to some or all of the activity transfer operations, e.g., operations described earlier with reference to  FIGS. 3-10 , through an “activity continuation” framework that is available at electronic devices that can participate in activity transfer operations. The activity continuation framework can provide the third-party application access to an operating system function, a daemon, a process, a service, etc., that performs at least some of the activity transfer operations. For example, in some embodiments, the provider of an electronic device and/or operating system for the electronic device provides an application programming interface (API) through which third-party applications can make calls to functions that facilitate activity transfer operations. In some embodiments, the activity continuation framework enables third-party applications (and third-party application developers) to transfer an activity from one electronic device to another electronic device without implementing (or even having knowledge of) the low-level details of activity continuation. 
     For example, in some embodiments, to enable the third-party application to participate in activity transfer operations, the third-party application developer provides activity descriptors for activities that the third-party application can perform and a method for the third-party application to be configured to perform an activity. In some of these embodiments, at an electronic device such as source electronic device  202 , the third-party application makes a call to a function provided by the activity continuation framework to provide an activity descriptor (and possibly extended activity data) for an activity performed in the third-party application. At an electronic device such as companion electronic device  204 , to configure the third-party application to perform the activity, the activity continuation framework can pass the extended activity data to the third-party application (e.g., through a command line switch or parameter, by using an object, etc.). Hence, the activity continuation framework can facilitate activity continuation for third-party applications with minimal effort and expense for the third-party application developer. 
     Messages Exchanged Between Electronic Devices 
       FIG. 16  presents a swim lane diagram illustrating messages exchanged between electronic devices in accordance with some embodiments. As can be seen in  FIG. 16 , the messages are exchanged between source electronic device  202  and companion electronic device  204  over a period of time, with activity advertisement  1600  occurring first in time and the lower messages occurring subsequently in time. Although  FIG. 16  is shown with messages exchanged in a particular order, in some embodiments, other messages are exchanged and/or messages are exchanged in a different order. Generally, electronic devices in the described embodiments exchange sufficient messages to enable the operations herein described. 
     The messages in  FIG. 16  are associated with two operations performed by source electronic device  202  and/or companion electronic device  204 . The first operation, which includes advertisement  1600 , is an activity advertisement operation such as is shown in  FIG. 3 . During the activity advertisement operation, source electronic device  202  broadcasts at least one activity advertisement  1600 . 
     The second operation, which includes request for extended activity data  1602 , extended activity data  1604 , and notification of activity transfer  1606 , is an activity transfer operation such as shown in  FIGS. 5-6 . During the activity transfer operation, companion electronic device  204  responds to activity advertisement  1600  with request for extended activity data  1602 . Upon receiving the request for extended activity data  1602 , source electronic device  202  responds by sending extended activity data  1604 . In some embodiments, after companion electronic device  204  uses the extended activity data to commence performing the activity at the second application, companion electronic device  204  sends notification of activity transfer  1606  to let source electronic device  202  know that the activity was transferred. 
     The foregoing descriptions of embodiments have been presented only for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the embodiments. The scope of the embodiments is defined by the appended claims.

Metadata:
Filing Date: 20150930
Publication Date: 20190319
Grant Date: 20190319
Priority Date: 20140530
Inventors: LINN, CHRISTOPHER S.
STATTENFIELD, KEITH
DUNN, ALEXANDER J.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L67/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F9/4856", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L67/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W4/80", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L67/535", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L67/535", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F9/4856", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W4/80", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L67/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W4/80", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F9/4856", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L67/10", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 55167763