Abstract:
Providing an electronic notification to an intended recipient includes communicating an electronic notification directed to an intended recipient, determining a lifespan related to a duration of relevance of the electronic notification, and providing the electronic notification to the intended recipient when the lifespan has not expired. The duration of relevance describes a time period during which information of the electronic notification reasonably may be expected usefully to inform an action or interest of the intended recipient. After the lifespan expires, provision of the electronic notification to the intended recipient may be prevented.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/406,078, filed Aug. 27, 2002. 
    
    
     TECHNICAL FIELD 
     This disclosure generally relates to systems and methods of delivering information to a delivery mechanism. 
     BACKGROUND 
     Online service providers make available to their users a wide range of information and services, much of which may be time sensitive. Users have virtually on-demand access to information and/or services regarding news, weather, stocks, banking, sports scores, and entertainment offerings. For example, users of online service providers such as America Online® or CompuServe® may view and retrieve information on a wide variety of topics from servers located throughout the world. Users also have the ability to access calendaring or scheduling services that may be used to track time sensitive items, such as, for example, a meeting, an assigned task, a birthday, and/or an anniversary. When time sensitive information is provided in an untimely fashion, that information may fail to provide a benefit, and, rather, may inconvenience and/or irritate the recipient of the information. 
     SUMMARY 
     In one general aspect, providing an electronic notification to an intended recipient includes processing an electronic notification directed to an intended recipient, determining a lifespan related to a duration of relevance of the electronic notification, and providing the electronic notification to the intended recipient when the lifespan has not expired. The duration of relevance describes a time period during which information of the electronic notification reasonably may be expected usefully to inform an action or interest of the intended recipient. After the lifespan has expired, provision of the electronic notification to the intended recipient may be prevented. The electronic notification may be provided to the intended recipient using various delivery mechanisms, such as, for example, a wired or wireless device, an email account, or a voicemail account (e.g., multiple instances of the electronic notification may be provided). 
     Implementations may include one or more of the following features. For example, providing an electronic notification to an intended recipient also may include monitoring for an online presence of the intended recipient during the lifespan and indicating the online presence when the online presence is detected. Based on the detected online presence of the intended recipient, the electronic notification may be provided to the intended recipient in an online format during the lifespan of the electronic notification. The electronic notification also may be provided to the intended recipient in an offline format during the lifespan of the electronic notification, such as, for example, when an online presence of the intended recipient is not detected. The electronic notification may be provided to the intended recipient based also on a delivery precedence associated with the electronic notification. In any event, after the electronic notification is provided to the intended recipient, the electronic notification may be deleted or disabled when the intended recipient does not access the electronic notification during the lifespan. 
     The electronic notification may be based on a critical time, such as, for example, a start or end time of an event, a goal date or drop-dead date of an assigned task, or a time at which an unscheduled event began. The lifespan may include a notice period indicative of a time period preceding the critical time and/or a response period indicative of a time period following the critical time. The lifespan may be defined in terms of a relative or an absolute time. 
     These general and specific aspects may be implemented using a method, a system, or a computer program, or any combination of systems, methods, and computer programs. 
     Other features will be apparent from the description, the drawings, and the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of an electronic communication system. 
         FIG. 2  is a flow diagram of a process implementable by the electronic communication system of  FIG. 1 . 
         FIG. 3  is a schematic diagram of an electronic notification delivery system. 
         FIGS. 4–6  illustrate an exemplary data structure that may be associated with electronic notifications deliverable by the system of  FIG. 3 . 
         FIGS. 7–9  are flow diagrams illustrating an exemplary process implementable by the notification delivery system of  FIG. 3 . 
         FIG. 10  illustrates an exemplary notification delivered to a user at a mobile device. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     An electronic notification may be delivered to an intended recipient based on a lifespan associated with the electronic notification. The lifespan may represent a period during which the electronic notification is expected to be relevant to the intended recipient. Delivery of the notification based on the lifespan enhances the likelihood that the electronic notification will be delivered to the intended recipient at a time at which the notification will be useful. The lifespan may be used to avoid untimely delivery of the notification that may cause the intended recipient to view the notification as not useful and/or as an annoyance. 
       FIG. 1  shows a generalized system  100  used to deliver an electronic message to an intended recipient  105  at a delivery mechanism  110  based on a lifespan of the message. The delivery mechanism  110  generally may include any device, system, and/or piece of code that relies on another service to perform an operation. The delivery mechanism  110  may include, for example, a fixed or mobile communication device, whether wired or wireless, and/or a software application, such as, for example, a messaging application or a browser. The delivery mechanism  110  also may include any protocols (i.e., standards, formats, conventions, rules, and structures) or delivery channels appropriate to communicating the electronic message. The protocols or delivery channels may include, for example, one or more other systems, such as for example, one or more wired networks and/or one or more wireless networks. 
     A message delivery service  120  communicates with a message source  140  and obtains a message directed to the intended recipient  105 . The message delivery service  120  includes a message conveyer  125 , a message lifespan module  130 , and a message information module  135 . 
     The message conveyer  125  may be configured to access, receive, or assign a message lifespan using the message lifespan module  130 , which may access message information using the message information module  135 , and to deliver the electronic message to the intended recipient  105  based on the message lifespan. That is, in general, the message delivery service  120  uses the message conveyer  125  to deliver the electronic message to the intended recipient  105  only while the electronic message is expected to be relevant based on the message lifespan as determined by the message lifespan module  130 . 
     The message conveyer  125  delivers the electronic message based on the message lifespan and/or the message information. The message lifespan may indicate an expected or actual period of relevance to the intended recipient  105 . The message lifespan may be based on the message information, and/or other information indicative of relevance. The message information may include, for example, message content, preferences of the intended recipient  105 , system definitions, a delivery rule, and/or any other information associated with the electronic message. 
     The message source  140  typically may include any source of an electronic message or information. The message source  140  may employ one or more protocols to transfer information internally or to deliver information to the message delivery service  120 . 
     Both the message delivery service  120  and the message source  140  may further include various mechanisms for delivering voice and/or non-voice data. The various mechanisms may include, for example, any applications, protocols, devices, or networks used to facilitate communication of electronic data. Both the message delivery service  120  and the message source  140  also may include or be included in a general-purpose or a special-purpose computer, at least one local area network, and/or at least one wide area network. The response to and execution of instructions received by the message delivery service  120 , the message source  140 , or any of their components (collectively the system services), may be controlled by, for example, a program, a piece of code, an instruction, a device, a computer system, or a combination thereof, for independently or collectively instructing the system services to interact and operate as described herein. 
       FIG. 2  illustrates a flow diagram of a process  200  implementable by, for example, the system  100  of  FIG. 1  to deliver a message to a user based on the message lifespan. The message source  140  communicates to the message delivery service  120  an electronic message directed to the intended recipient  105  (step  205 ). The message source  140  may communicate the message to the message delivery service  120  in response to activity of the message delivery service  120 , of another system or service, or of the message source  140 . The message delivery service  120  may use the message lifespan module  130  to determine a lifespan associated with the electronic message before delivering the message to the intended recipient  105  (step  210 ). The message delivery service  120  employs the message conveyer  125  to deliver the electronic message to the intended recipient  105  using the message lifespan (step  215 ). 
     Referring to  FIG. 3 , a generalized notification system  300  notifies a user  305  of information or an event by providing an electronic notification (notification) to one or more delivery mechanisms  310  associated with the user  305  during a lifespan of the notification. The lifespan is related to a durational relevance of the electronic notification (e.g., a time period during which the information of the electronic notification is relevant to the user). The notification system  300  provides the notification to the delivery mechanisms  310  using a network  315  and an online service  320 . Exemplary components of the notification system  300  are described in greater detail below. 
     The delivery mechanisms  310  generally are analogous to the delivery mechanism  110  of  FIG. 1 . Each delivery mechanism  310  may include any device, system, and/or piece of code that relies on another service to perform an operation. For example, a delivery mechanism  310  may include a device such as a telephone  310   a , a pen-enabled computer  310   b , a personal digital assistant (PDA) or mobile telephone  310   c , a notebook computer  310   d , and/or a desktop computer  310   e . The delivery mechanisms  310  also may include, for example, a Web browser, an email client, a synchronization client (e.g., a calendar synchronization client, or a task list synchronization client), an instant messaging (IM) client, a short message service (SMS) client, a business productivity application (e.g., a word processing program, or a spreadsheet program), and/or an operating system or operating system kernel residing on a device. The delivery mechanisms  310  may be arranged to operate within or in concert with one or more other systems, such as, for example, one or more LANs (local area networks) and/or one or more WANs (wide area networks). 
     Each of the delivery mechanisms  310  may be accessible to the online service  320 , and the user  305  may access the online service  320  using one or more of the delivery mechanisms  310 . For example, the user  305  may use the notebook computer  310   d  to access the online service  320 . 
     A delivery mechanism  310  may receive a notification and format the notification using a standard protocol, such as, for example, the standard generalized markup language (SGML), the extensible markup language (XML), the hypertext markup language (HTML), the extensible hypertext markup language (XHTML), the compact hypertext markup language (cHTML), the virtual reality markup language (VRML), the wireless markup language (WML), the voice extensible markup language (VXML), a document object model (DOM), or the dynamic hypertext markup language (DHTML). The formatted notification may permit the user  305  to respond to the notification. 
     The online service  320  generally may include, for example, any device, system, and/or piece of code configured to perform an operation requested by one or more of the delivery mechanisms  310  (e.g., the PDA or mobile telephone  310   c , a Web browser, the workstation  310   c , or another service). The online service  320  includes an access service  325 . that controls access to the online service  320  using, for example, authorization and/or authentication methods. The access service  325  may transform messages received from the network  310  into a communication protocol of the online service  320  (e.g., a synchronous transfer mode (ATM) or fiber distributed data interface (FDDI)). 
     The online service  320  also includes an information service  330 . The information service  330  typically includes different services and sources of information, such as, for example, third party information or services, email, a discussion group, a chat room, a news service, a broker service, a banking service, a shopping service, a weather service, the World Wide Web, or Internet access. The information service  330  may employ one or more protocols (i.e., standards, formats, conventions, rules, and structures) to transfer information internally or to deliver information to a user. Protocols employed by the information service  330  may include, for example, the Internet protocol (IP), the transfer connection protocol (TCP), the hypertext transfer protocol (HTTP), the file transfer protocol (FTP), the user datagram protocol (UDP), the layer two tunneling protocol (L 2 TP) and/or the simple mail transfer protocol (SMTP). 
     The online service  320  also includes a notification service  340  that provides a notification to the user  305  based on information of the information service  330 . The notification service  340  employs notification information  343  that may be determined based on information of the notification service  340 , information of the information service  330 , and/or information of other online services. 
     The notification information  343  may include user preferences and system definitions. For example, the notification information  343  may include a delivery preference of the user  305  determined based on information provided by the user  305  to the notification service  340 . The information provided by the user  305  to the notification service  340  also may be used to define a lifespan of a notification, and/or the lifespan may be defined expressly or implied by information of the information service  330 . For example, a notification may have an associated critical time (e.g., a time at which an event is scheduled to begin, or a time at which a notification is generated based on occurrence of an unscheduled event). A time period preceding the critical time may be referred to as a notice period while a time period following the critical time may be referred to as a response time. A user may ask the notification service to be notified of an event during a notice period prior to a critical time at which the event is scheduled to begin. The user also may indicate that the user does not care to be notified of the event beyond a response period following the scheduled start of the event. In sum, the user may indicate a time period during which the user perceives the notification to be useful or relevant. That time period may be used to define a lifespan for the notification, and may be described, for example, in terms of an absolute time or in terms of a relative time. 
     The system definitions may be generated by the system or by an administrator of the system. The system definitions may include, for example, definitions of classes of notifications, and/or definitions of each available notification. The system definitions also may define a lifespan of a notification (e.g., by forecasting a time period during which the notification is expected to be useful to a user). The definition of each notification includes one or more conditions to be satisfied before the notification may be delivered. When those conditions are satisfied, the notification is considered to be triggered, and the event or information that satisfied the conditions is known as the triggering event (or triggering information). For simplicity, the conditions satisfied by the triggering event may themselves be referred to as the triggering event. The triggering event (e.g., a triggering event of the information service  330 ) may include information defining an associated lifespan and/or a list of intended notification recipients. 
     Numerous examples of triggering events exist, but, for brevity, only a few of those examples are described here. Triggering events may be based, for example, on a promotional advertisement, an account balance, a portfolio status, a credit status, an online status, information that an order and/or a service is complete, or a message regarding confirmation, cancellation, and/or rescheduling of an appointment. Other examples include, but are not limited to, a weather forecast and/or adverse weather conditions of a particular geographic region; a particular date, holiday and/or other special occasion; an online status of another user; a change to a predetermined web page; or entertainment programming and/or ticket information. 
     The notification information also may include a record of users registered to receive notifications, and a record of the notifications (active notifications) that the users have registered to receive. Upon registration to receive a notification, a user may inform the notification service  340  of notification preferences regarding that notification. The notification service  340  may include those notification preferences in the notification information. 
     For example, the user  305  may access the notification service  340  to register for a stock alert and a birthday reminder. The notification service  340  may record that the user  305  has registered for the stock alert and the birthday reminder. At registration, the user  305  may provide the notification service  340  with notification preferences. In general, the notification preferences may include triggering information, a timing of the notification, a lifespan of the notification or information that may be used to determine a lifespan, a notification delivery preference, and/or a presentation method of the notification. A variety of delivery and/or presentation methods may be available for selection by the user  305 . For example, the user  305  may select to receive the notification as an instant message, an icon, a pop-up window, a video, a flashing indicator, and/or an audio or tactile alarm. The notification may be delivered to the user  305  while the user  305  is online, for example, and/or may be delivered to a wireless device (e.g., a mobile phone, a PDA, or a pager), a standard telephone, voicemail, and/or email if the user  305  so desires. In this manner, the user may arrange to be notified in a manner that the user anticipates will most likely provide the notification to the user without significant delay. 
     Referring back to the notifications selected by the user  305 , the user  305  may request delivery of a stock alert when a specified stock exceeds a 52-week high. The user  305  may indicate, however, that the user  305  does not wish to receive the stock alert more than three days after the stock exceeds the 52-week high. In this manner the user  305  provides information that may be used to define a lifespan for the stock alert. The stock alert will not be delivered after passage of the lifespan. Moreover, if delivered, the stock alert may be deleted if the user  305  does not access the stock alert (e.g., by viewing an associated pop-up window, and/or by accessing an associated email or voicemail message) prior to passage of the lifespan. 
     As another example, the user  305  may request delivery of a birthday reminder one week prior to the specified birthday and delivery of a subsequent reminder again the day before, and to be reminded through a non-intrusive email. The subsequent reminder may replace the initial reminder if the initial reminder has not been accessed already. Moreover, the user  305  may consider two weeks an upper bound for an acceptable belated birthday wish. As a result, the user  305  may indicate a desire to not receive or see the birthday reminders later than two weeks after the birthday. Based on this information, the email notification of the birthday may be removed automatically two weeks following the birthday if the user  305  has not accessed the notification by that time. For each birthday reminder, the associated lifespan may be defined as the time between generation of the birthday reminder and the birthday plus the two weeks following the birthday after which the user  305  no longer wishes to receive or see the reminder. 
     The notification service  340  includes a notification generation service  346  that generates notifications based on the information maintained by the information service  330 , and a notification delivery service  349  that delivers the notifications to the user  305  using one or more of the delivery mechanisms  310 . The notification service  340  also may include a print service, a file access service, an IM service, an operating system, an operating system kernel, an authentication service, an authorization service, and/or any combination of these or other services. 
     In general, the notification generation service  346  generates notifications based on the notification information maintained by the notification service  340 . The notification generation service  346  communicates with the information service  330  (e.g., by polling the information service  330  or by receiving updates from the information service  330  periodically or upon a triggering event) to identify when a notification trigger is satisfied, for example, by the occurrence of a particular event or by the presence of predetermined information. Alternatively, the information service  330  itself may note the triggering event and notify the notification generation service  346 . In either event, the notification generation service  346  generates and communicates a corresponding notification to the notification delivery service  349  for delivery. 
     Typically, the notification generation service  346  includes a software program or piece of code to control reception and/or retrieval of information from the information service  330 . The notification generation service  346  may receive the information from the information service  330 , and then may determine whether the information corresponds to a triggering event of a notification of interest to the user  305 . 
     Alternatively, or in addition, a notification may be generated by the information service  330  (e.g., by a third party service that provides a certain category of notifications, such as stocks, news, or weather) including definition of an associated lifespan. The notification service  340  may include an application programming interface (API) structured for configuring and/or communicating electronic notifications with the notification service  340 . Content for the notification may be provided by the notification generation service  346 , the information service  330 , or by any other third party, including the user  305 . In one implementation, the notification service  340  queries user  305  as to whether the user  305  would like to receive various categories of third party notifications. For example, the notification service  340  may communicate with third party suppliers of computer merchandise and may query the user  305  as to whether the user  305  would like to receive notifications from any or all third parties that supply computer merchandise. In another implementation, the user  305  may register for a notification at a web site of a third party. Once the user  305  has registered to receive the notification, the third party may directly or indirectly generate the notification. 
     The notification delivery service  349  may be configured to receive the notification from the notification generation service  346  and to deliver the notification to the user  305 . The notification delivery service  349 , alone or in conjunction with other services, may perform sorting, prioritizing, or other types of organizational processing on the notification so that the notification is delivered appropriately to the user  305 . 
     More particularly, the notification delivery service  349  may monitor for an online presence of the user  305 . The notification delivery service  349  may deliver the notification to the user offline (e.g., to an email account or to a voicemail account). In the alternative, or in addition, when an online presence of the user  305  is indicated, the notification delivery service  349  may deliver the notification to the user  305  online (e.g., using a pop-up window, an instant message or a Web browser). In any event, the notification delivery service  349  delivers the notification to the user  305  based on the lifespan and other notification information  343 . 
     In addition, when multiple instances of a notification are provided to a user, the multiple instances may be associated. Based on the association between the multiple notification instances, access by the user  305  of one notification instance may be used to disable or delete some or all of the other notification instances. In this manner, the notification delivery service  349  may deliver the notification to the user  305  with a minimum of delay while not burdening the user with redundant notifications. 
     For example, the notification delivery service  349  may deliver a notification to an email account of the user  305  based on a preference indicated in the notification information  343 . Later, the notification delivery service  349  may detect that the user  305  is online during the lifespan period and may deliver an associated notification to the user  305  using, for example, a pop-up window. If the user  305  first accesses the notification delivered to the email account (e.g., because the user  305  was reading email when the pop-up window was delivered), the user  305  may cause the associated redundant pop-up window notification to be vacated or removed. Alternatively, the user  305  may fail to access either notification during the lifespan period, which causes both notifications to be vacated. 
     The notification delivery service  349  may deliver notifications in a certain order based on a delivery precedence. The delivery precedence may be related to notification subject matter and/or time sensitivity (e.g., as measured by lifespan). For example, a delivery precedence may define that a notification for a severe weather alert has a higher delivery precedence than a notification of a baseball score. Similarly, the delivery precedence may define that a notification with only thirty minutes of remaining lifespan has a higher precedence than a notification having 36 hours of remaining lifespan. 
     The network  315  typically allows direct or indirect communication between the delivery mechanism  310  and the online service  320 , irrespective of physical or logical separation. Examples of a network  315  include the Internet, the World Wide Web, WANs, LANs, analog or digital wired and wireless telephone networks (e.g., PSTN, ISDN or xDSL), radio, television, cable, satellite, and/or any other delivery mechanism for carrying data. The network  315  may be secured or unsecured. 
     Each of the delivery mechanism  310 , the network  315 , and the online service  320  may further include various mechanisms for delivering voice and/or non-voice data, such as, for example, the short message service, the wireless application protocol (WAP), the transport connection protocol (TCP), the Internet protocol (IP), the World Wide Web, one or more local area networks, and/or one or more wide area networks. The delivery mechanism  310 , the network  315 , and the online service  320  also may include analog or digital wired and wireless telephone networks, such as, for example, public switched telephone networks (PSTN), integrated services digital networks (ISDN), various types of digital subscriber lines (xDSL), advance mobile telephone service (AMPS), global system for mobile communications (GSM), general packet radio service (GPRS), code division multiple access (CDMA), radio, cable, satellite, and/or other delivery mechanisms for carrying voice or non-voice data. 
     One or more other services may be included in the components of notification delivery system  300  and/or these components (hereinafter the system services) may be included as part of one or more other services. For example, the system services may include or be included in a general-purpose or a special-purpose computer (e.g., a personal computer, a PDA, or a device specifically programmed to perform certain tasks), at least one local area network, and/or at least one wide area network. In either case, the response to and execution of instructions received by any or all of the system services may be controlled by, for example, a program, a piece of code, an instruction, a device, a computer system, or a combination thereof, for independently or collectively instructing the services to interact and operate as described herein. 
       FIG. 4 . illustrates a notification data structure  400  that may be used by the notification service  320  of  FIG. 3  to maintain the notification information  343 . The notification data structure  400  is structured as a hierarchical tree and provides a logical representation of the notification information  343 . For example, a highest hierarchical level of the notification data structure  400  includes a notification global-level  405  that includes a notification global defaults node  406  representative of a generalized notification. 
     A lower class-level  410  of the notification data structure  400  further defines notifications according to notification classes. For example, as shown, the notifications may include a class of notifications that are event-based alerts  413 , and a class of notifications that are date-based reminders  415 . Other notification classes are possible, such as, for example, a class for notifications allowing public membership, a class for notifications with private membership, and a class based on a quality of one or more targeted recipients. 
     The notification data structure  400  includes a type-level  430  that further defines the notifications according to notification type. The alerts class  413  includes, for example, an auction closeout alert type  433  and a sale alert type  435 . Similarly, the reminders class  415  includes a meeting reminder type  437 , and a to-do reminder type  439 , among others. Still further, the notification data structure  400  includes an instantiation-level  440  to identify and define activated instantiations of the notification type. Each notification type (e.g., the auction closeout alert type  433 ) may include active instantiations of that notification. For example, the auction closeout alert type  433  may include instantiations of that alert activated by user registration (e.g., auction closeout alert # 1   441  through auction closeout alert #n  442 ). Other instantiations include sale alert # 1   443  through sale alert #n  444 , meeting reminder # 1   445  through meeting reminder #n  446 , and to-do reminder # 1   447  through to-do reminder #n  448 . 
     Each level of the notification data structure  400  may include both system definition information and user preference information for the notification information  343 . For example, the notifications global-level  405  may include system-defined delivery information and user-defined delivery information. To the extent that there is contradiction, the user preference information may preempt the system definition information for a given hierarchical level of the notification data structure  400 . Moreover, each node of the notification data structure  400  may be configured to inherit notification information  343  from a node of a higher hierarchical level from which the node depends. Stated differently, notification information  343  may pass from a higher hierarchical level of the notification data structure  400  to a lower level to provide information missing at the lower level. 
     For example, the notifications global node  406  includes a global delivery definition  407 . Since the alerts class lacks its own delivery definition, the alerts class defaults  413  inherit the global delivery definition  407  from the notification global defaults  406 . The auction closeout alert type  433  also fails to define a delivery definition, such that the auction closeout alert type  433  inherits the global delivery definition  407  from the alerts class  413 . However, auction closeout alert # 1   441 , an instantiation of the auction closeout alert type  433 , includes a local delivery definition  449 . To the extent that the local delivery definition  449  is complete, that definition overrides the global delivery definition  406  that it would inherit otherwise. On the other hand, auction closeout alert #n  442 , a further instantiation of the auction alert type  433 , does not include a delivery definition and inherits the global delivery definition  407  from the auction closeout alert type  433 . 
       FIGS. 5 and 6  illustrate an implementation of the notification data structure  400  that includes data structures for structuring the system definition information and the user preference information, respectively. The exemplary data structures of  FIGS. 5 and 6  are similar and parallel each other. 
     Referring to  FIG. 5 , the notification data structure  400  includes system definitions  500 . The system definitions  500  include global definitions  510 , class definitions  540 , and type definitions  550 . The global definitions  510 , for example, define a form of a global lifespan  512  as including a sum of two time periods, T 1  and T 2 . The time periods T 1  and T 2  represent a notice period and a response period, respectively. As indicated by the null value, however, the global definitions  510  do not provide a global default lifespan value. 
     The global definitions  510  also indicate a global delivery precedence that controls whether and/or when the notification delivery service  349  delivers a notification to a particular delivery mechanism. More specifically, the global definitions  510  instruct the notification delivery service  349  to select the following delivery mechanisms as delivery recipients in the order of preference shown: (1) an online device  514 , if the user is online, (2) a wireless client  516 , if wireless delivery is enabled for the user, and (3) an email inbox  518   a . Lastly, an email archive  518   b  is provided for, but is not activated as a delivery option in this configuration. 
     Delivery to the online device  514  is designated as “concurrent.” Concurrent delivery indicates that the notification will be delivered online upon detection of an online presence of the user  305 , even if the notification already had been delivered to the user  305  offline. The global definitions also define notification priority  520  to be “not urgent,” and that a “quiet time”  522  applies between 9:00 PM and 8:00 AM during which only urgent notifications are delivered to attract the immediate attention of the user  305 . 
     The system definitions  500  also include class definitions  540  for an alert class  543  of notifications and for a reminders class  546  of notifications. In this example, neither the alert class  543  nor the reminders class  546  includes any system definition information. 
     Additionally, the system definitions  500  include type definitions  550  that define, for example, an auction closeout alert type  555 , a sale alert type  575 , a meeting reminder type  580 , and a to-do reminder alert  585 . For brevity, only the auction closeout alert type  555  is described in detail as the other alert types are similar in most relevant aspects. The auction closeout alert type  555  defines, for example, a trigger event  557  on which the auction closeout alert type  555  is triggered. In this case, the trigger event  557  occurs upon reaching a time thirty minutes prior to closeout of a specified auction. The auction closeout alert type  555  also defines a thirty minute lifespan  559  in which T 1   559   a  is equal to thirty minutes and T 2   559   b  is equal to zero minutes. In this case, T 1   559   a  is indicative of a notice period between generation of the alert and occurrence of the auction closeout. On the other hand, T 2   559   b  represents a response period following the auction closeout during which meaningful participation in the auction may occur. Because no further participation is permitted after the auction closes, the value of T 2   559   b  is set to zero minutes. In addition, although it does not do so here, the auction closeout alert type  555  may define an associated delivery precedence  561  and notification priority  563 . 
     One or more active instantiations may be associated with each notification type. The active instantiations may include corresponding system definition information. For example, auction closeout alert # 1   565  is one instantiation of the auction closeout alert type  555 . Auction closeout alert # 1   565  includes information that further defines a trigger event of the alert. More specifically, the trigger event information  567  identifies an associated auction using an auction identification number, 53ZX793, and a subject of the auction, a 1957 Chevrolet Bel Air. The auction closeout alert # 1   565  also may define the lifespan  569 , the priority  571  of the alert, and the delivery precedence  573 , although those definitions are left null valued in this example. Additionally, the auction closeout alert # 1   563  defines a membership list  574  of users registered to receive the notification and an identification associated with each user. The identification may include, for example, a name of the user, an identification of the user, a login, a password, and/or a screen name. In the example shown, the user is identified by the screen name Will Robinson. Based on the screen name of the user Will Robinson, the notification service may access stored user preferences of Will Robinson. 
     Referring briefly to instantiations of other notifications types, a lifespan is defined by each of sale alert # 1   576 , meeting reminder # 27   581 , and to-do reminder # 12   586 . With respect to the sale alert # 1   576 , the lifespan values T 1   578   a  (3 hours) and T 2   578   b  (6 hours) may represent a time remaining until the sale begins, and a duration of the sale, respectively. With respect to the meeting reminder # 27   581 , the lifespan values T 1   583   a  (15 minutes) and T 2   583   b  (15 minutes) may represent a time remaining until the meeting is scheduled to begin, and a time period after which meeting attendance is judged no longer to be beneficial, respectively. With respect to to-do reminder # 12   586 , the lifespan value T 2   588   b  (MaxTime) may represent that the relevance of the subject of the to-do reminder is not time dependent, and, hence, that the lifespan should be treated as infinite. 
     Each of these lifespans  578 ,  583 , and  588  is defined at the instantiation level because each instantiation of the sale alert type  575 , the meeting reminder type  580 , and the to-do reminder type  585  is expected to vary significantly from other instantiations of the same type. For example, sale alerts may vary significantly to reflect the timing and duration of the subject sales. More specifically, subject sales may include a one-hour internet sale as well as a full-week sale at a local department store. Because the associated lifespans are expected to vary accordingly, the lifespans are defined at the instantiation level. The length and timing of a meeting and the timing constraints associated with a to-do task may be expected similarly to vary. 
     Referring to  FIG. 6 , the notification data structure  400  also may include a user profile with user preferences  600 . Like the system definitions  500 , the user preferences  600  include global preferences  610 , class preferences  640 , and type preferences  650 . In the illustration of  FIG. 6 , all of the global preferences are null valued except for wireless delivery preference  616 . That preference indicates that mobile phone # 1  is enabled generally to receive notifications for Will Robinson. To enable mobile phone # 1  to receive notifications, Will Robinson may identify mobile phone # 1  as a preferred delivery mechanism and may identify contact information related to mobile phone # 1 , such as, for example, an associated phone number (202) 997–6363. Although mobile phone # 1  is enabled, no associated delivery precedence is provided. 
     Class preferences  640  also are provided for both the alerts class  643  and the reminders class  646 . Those preferences, however, are null valued in this illustration. 
     The type preferences  650  may include preferences for various notification types for which Will Robinson has registered, such as, for example, the auction closeout alert type  655 , the sale alert type  675 , the meeting reminder type  680 , and/or the to-do reminder type  685 . For brevity,  FIG. 6  provides detail only for the auction closeout alert type  655 . The auction closeout alert type  655  includes type-level preferences and a single auction closeout alert instantiation (i.e., auction closeout alert # 1   665 ) having associated instantiation preferences. The type preferences for the auction closeout alert type  655  are null valued. 
     Nevertheless, at the instantiation level, auction closeout alert # 1   665  defines the T 1  component  669   a  of the lifespan  669  as 1 hour, based, for example, on a desire of the user to receive notification 1 hour before closeout. The auction closeout alert # 1   665  also defines the following delivery precedence  671 : (1) an online device (if the user is online), (2) a mobile phone # 1 , (3) a PDA, (4) a mobile phone # 2 , (5) a pager, and (6) an email inbox. Lastly, an email archive is identified to always receive notification. In addition, the auction closeout alert # 1   665  defines the notification priority  673  as “urgent,” while leaving “quiet time”  674  undefined as a null value. 
       FIG. 7  illustrates a flow diagram of a process  700  implementable by, for example, the system of  FIG. 3  to deliver a notification to a user based on a lifespan of the notification and other notification information  343 . As previously described, the notification information  343  may include system definitions and user preferences associated with the notification. Initially, the user  305  accesses the notification service  340  to activate a notification (step  705 ). For example, the user  305  may subscribe to an existing notification such as the auction closeout alert described previously. Subscription to the auction closeout alert creates an active instantiation of that alert (e.g., auction closeout alert # 1 ) associated with the user  305 . 
     Based on the notification information  343 , including the trigger event for the notification, the notification generation service  346  determines whether information of the information service  330  triggers the notification (step  710 ). For example, the notification generation service  346  may poll the information service  330  to detect the occurrence or nonoccurrence of the trigger event. As long as the trigger event is not detected, the notification generation service  346  may continue to monitor for occurrence of the trigger event. 
     The notification generation service  346  also may inform the information service  330  of the trigger event, or the information service  330  itself may determine the trigger event. In either case, the information service  330  may monitor its information for occurrence of the trigger event. When the information service  330  detects that the trigger event has occurred, the information service  330  may notify the notification generation service  346  of that occurrence. For example, the information service  330  may include an online auction service (e.g., eBay®) that may monitor auction activity for a trigger event selected by an auction participant. When that event is detected, the online auction service may inform the notification generation service  346 . 
     After the notification has been triggered (step  710 ), the notification delivery service  349  resolves a delivery instruction associated with the notification (step  715 ). The delivery instruction is resolved based on the notification information  343  (e.g., the lifespan), including the system definitions and/or user preferences associated with the notification (step  715 ). 
     The notification delivery service  349  delivers the notification based on the previously resolved delivery instruction (step  720 ). The delivery instruction indicates a lifespan during which the notification may be delivered and/or accessed by the user. The delivery instruction may direct the notification delivery service  349  to monitor for an online presence of the user  305  (e.g., that the user  305  is browsing the web, has an active instant messaging session, is online using a television, is online using a game console, is online using a networked radio, or is active in a chat room discussion) within the lifespan period. If an online presence is detected, the notification delivery service  349  delivers the notification to the user  305  online. 
     Referring to  FIG. 8 , a delivery instruction may be resolved (step  715 ) by determining delivery instruction information from an instantiation-level user preference and/or system definition (step  805 ). If no gaps are identified in the delivery instruction information (step  810 ), the delivery instruction is formed based on the delivery instruction information (step  815 ). Otherwise, if gaps are identified (step  810 ), additional delivery instruction information is inherited from a type-level user preference and/or system definition (step  820 ). The supplemented delivery instruction information is evaluated for completeness again (step  825 ). If the supplemented delivery instruction information is complete, the notification delivery service  349  forms the delivery instruction based on that information (step  815 ). Otherwise, if gaps remain in the delivery instruction information, that information inherits additional delivery instruction information from a class-level user preference and/or system definition (step  830 ), and the process of evaluating the completeness of the supplemented delivery instruction information is repeated (step  835 ). As before, the notification delivery service  349  forms a delivery instruction from the supplemented delivery information where that information is complete (step  815 ). Otherwise, the notification delivery service  349  forms the delivery instruction (step  815 ) after the delivery instruction information is further supplemented through inheritance based on a global-level user preference and/or system definition (step  840 ). 
     The process of  FIG. 8  may be used to resolve a delivery instruction for auction closeout alert # 1  described with respect to the system definitions  500  and the user preferences  600  of  FIGS. 5 and 6 , respectively. Initially, delivery instruction information is determined from the instantiation-level user preferences  660  of auction closeout alert # 1  (step  805 ). That information defines the T 1  value of the lifespan as 1 hour, but leaves the T 2  value undefined. Although undefined by the user preferences  660 , the trigger event is defined partly by the instantiation-level system definitions  563  that provide the auction ID and that identify the subject of the auction. 
     The instantiation-level user preferences  660  define a delivery precedence  663  as described previously: (1) an online device (concurrently, if the user is online), (2) a mobile phone # 1 , (3) a PDA, (4) a mobile phone # 2 , (5) a pager, and (6) an email inbox. In addition, an email archive is identified to always receive notification. The user preference information  660  of auction closeout alert # 1  also defines a notification priority  666  as “urgent,” but leaves “quiet time”  669  undefined. 
     The delivery instruction information provided above fails to define fully the trigger event. The delivery instruction information also fails to define the T 2  value of the lifespan or the “quiet time”  669 . Moreover, the detailed delivery precedence  663  described above is open-ended. That delivery precedence  663  would not be contradicted by adding, for example, an additional delivery mechanism to assume a seventh place role in the delivery precedence. In sum, gaps exist in the delivery instruction information (step  810 ). 
     The gaps in the delivery instruction information are filled partially by information of the type-level system definitions  563  (step  820 ). More particularly, the type-level system definitions  550  further define the trigger event as occurring 30 minutes prior to closing time of the auction. The type-level system definitions  550  also define as zero the value of T 2  of the lifespan. These additional and consistent pieces of information are inherited by the delivery instruction information, while contradictory information (e.g., the definition of T 1  of the lifespan as 30 minutes) is not. Despite the inherited information, gaps remain in the delivery instruction information. For example, “quiet time” remains undefined and addition to the delivery precedence definition is not foreclosed (step  825 ). 
     The remaining gaps in the delivery instruction information are not filled by any information of the class-level system definitions  540  or user preferences  640  (steps  830 – 835 ). Likewise, the global-level user preferences  610  do not provide a “quiet time” definition. The global-level user preferences  610  do include some delivery information  616 . That information, however, is not additional to delivery precedence information already determined. More specifically, that information simply notes that mobile phone # 1  is enabled to receive a wireless notification, information already included in the instantiation-level preference information  663  that also provides that mobile phone # 1  ranks number three in the delivery precedence. 
     However, the global-level system definitions  510  define “quiet time”  524  as between 9:00 PM and 8:00 AM, information additional to that already obtained. This additional delivery instruction information is inherited to fill the prior information gap (step  840 ). Note also that the global-level system definitions  510  provide delivery precedence information  512 – 520  and priority information  522  that is inconsistent with the aggregated delivery instruction information and, therefore, is not inherited. 
     Having determined the relevant delivery instruction information, the notification delivery service  349  then forms a delivery instruction based on that information (step  815 ). The delivery instruction may be formed, for example, by converting the relevant delivery instruction information into a format or protocol required for delivery. The delivery instruction may remain substantively similar to the relevant delivery instruction information. In this example, the delivery instruction provides that the notification is “urgent,” that a “quiet time” from between 9:00 PM and 8:00 AM applies, and that the notification should be delivered within a one hour lifespan according to the following delivery precedence: attempt delivery first to an online device (if the user is online); second, to a mobile phone # 1 ; third, to a PDA; fourth, to a mobile phone # 2 ; fifth, to a pager; and sixth, to an email inbox. Because concurrent delivery to the online device is indicated, the notification will be delivered online upon detection of an online presence of Will Robinson, even if the notification already had been delivered to Will Robinson offline. Lastly, the notification is to be delivered to an email archive, irrespective of the lifespan. 
     Referring to  FIG. 9 , delivering the notification according to the delivery instruction may include determining whether the lifespan of the notification has been expended (step  905 ). If the lifespan is expended, the notification delivery service does not deliver the notification and the process is finished (step  910 ). 
     If the lifespan is not expended (step  905 ), then the notification delivery service determines whether the user  305  is online (step  915 ). If the user  305  is online, the notification delivery service  349  determines further whether the user  305  is away temporarily (e.g., although having an established online session using an online delivery mechanism, the user  305  has marked himself as “away,” or the user  305  has engaged in no activity using the online delivery mechanism for a predetermined period of time) (step  920 ). If the notification delivery service  349  determines that the user  305  is online and is not away from the online delivery mechanism, the notification delivery service  349  delivers the notification to that online delivery mechanism (step  925 ). 
     If the notification delivery service  349  determines, however, that the user  305  is not online (step  915 ), or is away from the online delivery mechanism (step  920 ), then the notification delivery service  349  determines again if the lifespan is expended (step  905 ) and continues to monitor for an online presence of the user  305  (steps  915  and  920 ). 
     Concurrently with online delivery, the notification delivery service determine whether it presently is “quiet time” for the user  305  (step  930 ). The notification delivery service  349  also determines whether the notification is designated as “urgent” (e.g., a notification might be marked “urgent” when the notification provides an alert that a tornado has been spotted near the user&#39;s home address) (step  935 ). Where the notification delivery service  349  determines that it is not “quiet time” or that the notification is “urgent” (i.e., “urgency” overrides “quiet time”), the notification delivery service  349  determines whether wireless notification is available for the user  305  (e.g., through notification to a mobile phone, a PDA, a pager) (step  940 ). If wireless notification is available, the notification delivery service  349  determines a wireless delivery mechanism at which the user  305  prefers to receive the notification (step  945 ) and delivers the notification to that wireless delivery mechanism (step  950 ). 
     However, should the notification delivery service  349  determine that it is “quiet time” (step  930 ) and that the notification is not “urgent” (step  935 ), or that wireless notification is unavailable (step  940 ), the notification delivery service  349  delivers the notification to an email inbox (step  955 ). Irrespective of delivery or lack of delivery to other delivery mechanisms, the notification delivery service  349  also delivers the notification to an email archive (step  960 ). 
     Whether the notification is delivered online, to a wireless device, or to an email inbox, the notification delivery service  349  may monitor whether the lifespan of the notification becomes expended before the notification is accessed by the user  305  (steps  965  and  970 ). If the lifespan of the notification becomes expended before the user accesses the notification, the notification may be vacated (e.g., the notification may be deleted from a notification delivery mechanism to which the notification was delivered) (step  975 ) and the delivery process may be concluded (step  910 ). Otherwise, if the notification is accessed by the user before the notification lifespan becomes expended, the notification delivery service may provide the notification to the user (step  980 ), and the delivery process may be concluded (step  910 ). 
     Alternatively, or in addition, after the user accesses the delivered notification (step  970 ), the notification delivery service  349  may cause to be vacated redundant instances of the same notification that were delivered to other delivery mechanisms. For example, those redundant instances of the notification might be vacated as the lifespan period becomes expended. In another implementation, accessing of the notification by the user  305  may trigger the notification delivery service to cause the redundant instances of the notification to be vacated. For example, access by the user of an online notification may cause the notification delivery service to transmit a secured (e.g., authenticated and encrypted) recall message to an email inbox to which a now redundant notification was delivered. The secured recall message may act to remove the redundant notification from the inbox before the redundant notification becomes a source of inconvenience to the user. 
       FIG. 10  illustrates an auction closeout alert that may be delivered to a PDA or mobile phone of a user. The auction closeout alert may be any type of instant message, pop-up window, icon, and or audible or tactile alarm capable of gaining the attention of the user. The auction closeout alert may provide information such as an alert identifier, identification of the auction item, a bid status at time of notification, and a date and time stamp of when the auction closeout alert was generated. The PDA or mobile phone also notifies the user “Alert! Will Robinson. Auction 53ZX793 for a 1957 Chevy Bel Aire closes in one hour. At the time of this notice, you have the high bid.” In another aspect, the auction closeout alert may include an edit button for editing the presentation of the alert, and a respond/more information button for accessing the auction using the online service to update a bid and/or to obtain more detailed information regarding the auction. 
     Other implementations are within the scope of the following claims.