Patent Publication Number: US-7912903-B2

Title: Method and system for processing instant messenger operations dependent upon presence state information in an instant messaging system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to instant messaging systems and, more particularly, to instant messaging presence state information. 
     2. Description of the Related Art 
     Instant messaging systems, such as SunONE Instant Messenger, AOL Instant Messenger (AIM), and Yahoo! Messenger, for example, may provide a convenient method for users of a computer system to interact with one another in various different ways. Generally, instant messaging systems provide the capability for several computer system users to “chat” or exchange messages nearly instantaneously, such that when one user enters and sends a message, another user sees that message soon thereafter. In many embodiments, instant messaging systems may provide users engaging in such a chat the ability to see their messages interspersed with those of other respondents and displayed in the order the messages were exchanged. Instant messaging systems may thus provide a context for dialogue when other modes of communication are inaccessible or inconvenient. 
     In some embodiments, instant messaging systems may provide other features in addition to a chat operation. For example, a given instant messaging system may provide for users to establish static virtual “conference rooms,” which may permit users to engage in chats with whoever happens to be in the virtual conference room at a given time. Such a feature may, for example, enable users situated at different locations to conduct group meetings. Additionally, a given instant messaging system may enable users to send alerts to one another. In one embodiment an instant messaging alert may be used to convey information when no response is desired, such as a meeting reminder, for example. These and other types of instant messaging operations are discussed in greater detail below. 
     In an instant messaging environment, some indication of whether or not a given user is available to engage in instant messaging operations may be useful. For example, users may temporarily step away from their desks, attend meetings, or leave the office. Even when physically present, users may be busy with other tasks and unavailable for instant messaging operations. Consequently, in some instant messaging system embodiments an instant messaging presence state is implemented. In one embodiment, such a presence state may include a status indication, such as a text message that a user selects from a list or enters directly. Changes to a user&#39;s presence state may then become visible to other users of the system. For example, if a given user is busy with other tasks, he or she may select a “busy” instant messenger presence state, which may indicate a busy status to other users. 
     The presence state may effectively indicate a given user&#39;s presence status to other users of a system. However, a user may fail to select the presence state that actually corresponds to that user&#39;s status at a given time. For example, a given user may be busy with other tasks but forget to select a busy presence state. Thus, other users may potentially interrupt the given user with requests to chat or other instant messenger operations. Likewise, if a given user indicates an availability to chat but is actually away at an appointment, other users may mistakenly assume the given user is in fact available. 
     Even if a user selects a busy presence state to notify other users of a desire not to be disturbed, this may not actually prevent other users from attempting to initiate instant messenger operations with the busy user. For example, another user could simply ignore the busy presence state and send alerts, requests to chat, or other operations to the busy user. Additionally, changes in presence state may not result in relevant instant messenger operations being performed. For example, a busy user may wish to chat with another user once he is no longer busy, but may forget this fact by the time he changes his presence state to reflect an idle status. 
     SUMMARY OF THE INVENTION 
     Various embodiments of a method and system for processing instant messenger operations dependent upon presence state information in an instant messaging system are disclosed. In one embodiment, the method may include receiving an instant messaging operation directed to a given user, where the given user is not offline; determining a presence state of an instant messenger in response to receiving the instant messaging operation, where the presence state corresponds to the given user; and selectively processing the instant messaging operation dependent upon the presence state in response to the determination. 
     In another embodiment, the method may include storing an instant messaging operation associated with a given presence state of an instant messenger, where the given presence state corresponds to a given user; detecting a transition to the given presence state subsequent to storing the operation; and performing the instant messaging operation in response to the detection. 
     In one embodiment, the system may include a computer system and an instant messenger software module configured to execute on the computer system. The instant messenger software module may be further configured to receive an instant messaging operation directed to a given user, where the given user is not offline; determine a presence state of the instant messenger software module in response to receiving the instant messaging operation, where the presence state corresponds to the given user; and selectively process the instant messaging operation dependent upon the presence state in response to the determination. 
     In another embodiment, the system may include a computer system and an instant messenger software module configured to execute on the computer system. The instant messenger software module may be further configured to store an instant messaging operation associated with a given presence state of the instant messenger software module, where the given presence state corresponds to a given user; detect a transition to the given presence state subsequent to storing the operation; and perform the instant messaging operation in response to the detection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating one embodiment of an instant messaging software system. 
         FIG. 2  is a block diagram illustrating one embodiment of a system configured to execute instant messaging system software modules. 
         FIG. 3  is a block diagram of one embodiment of an exemplary computer system. 
         FIG. 4A  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during processing of presence state using computer system activity information. 
         FIG. 4B  is a flow diagram illustrating the operation of a second embodiment of an instant messaging system during processing of presence state using computer system activity information. 
         FIG. 5  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during processing of presence state using schedule information. 
         FIG. 6  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during selective processing of instant messaging operations. 
         FIG. 7  is a flow diagram illustrating the operation of another embodiment of an instant messaging system during selective processing of instant messaging operations. 
         FIG. 8  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during execution of instant messaging operations in response to presence state changes. 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Overview of Instant Messaging System Software and Hardware 
     Turning now to  FIG. 1 , a block diagram illustrating one embodiment of an instant messaging software system is shown. In the illustrated embodiment, instant messenger (IM) system  10  includes the following software modules: instant messenger clients  100   a  and  100   b , web browsers  110   a  and  110   b , IM multiplexor  130 , IM server  140 , directory server  150 , SMTP server  160 , web server  170 , IM resources  180 , and calendar server  190 . Arrows interconnecting the software modules illustrated in  FIG. 1  represent communication paths between the interconnected modules, through which data and control information may be passed. 
     Communication along the illustrated paths may be implemented using a variety of software techniques. For example, in one embodiment, software function calls such as may be defined in an application programming interface (API) may be used to implement communication between software modules. In another embodiment, software modules may communicate by passing messages, for example directly through a commonly-defined message passing port interface or indirectly through reading and writing shared memory. In still another embodiment, software modules may communicate over a network infrastructure using a protocol such as hypertext transfer protocol (HTTP), file transfer protocol (FTP), or transmission control protocol (TCP), for example. The function of specific interconnections among software modules illustrated in IM system  10  is described in greater detail below in conjunction with the descriptions of the relevant modules. 
     In one embodiment, instant messaging may provide a mode of communication among two or more users of a computer system that minimally provides the capability for users to exchange text messages in real time, which messages may be referred to as instant messages. In one embodiment, instant messaging may further allow users exchanging instant messages to view all instant messages exchanged (including a user&#39;s own entered instant messages) in the order they were exchanged. Capabilities provided by instant messaging may be referred to generically herein as instant messaging operations, and the specific capability just described may be referred to herein as a chat operation. Depending on implementation, instant messaging may include numerous other instant messaging operations as described in detail below. In one embodiment, an instant messenger may comprise a software application or a hardware device with which a given user interacts to engage in instant messaging operations. An instant messenger may also be referred to herein as an instant messenger client. In one embodiment, an instant messaging software system may comprise one or more software modules configured to implement instant messaging, as described in further detail below. 
     Instant Messenger Client and Operations 
     Instant messenger (IM) clients  100   a  and  100   b , which may be referred to individually or collectively herein as IM client  100 , may be configured to provide access to instant messaging operations for one or more users of IM system  10 . Although only two instant messenger clients are illustrated in  FIG. 1 , it is contemplated that IM system  10  may include an arbitrary number of IM clients  100 . In one embodiment, IM client  100  may provide access to instant messaging operations that may include a chat operation, an alert operation, a polling operation, and a news channel operation, although in other embodiments it is contemplated that different kinds and combinations of instant messaging operations may be provided. General descriptions of the operation of the chat, alert, polling and news channel operations from the perspective of IM client  100  follow. Greater detail regarding the operation of the other modules of IM system  10  is provided in subsequent sections. 
     In one embodiment, the chat operation may provide a real-time conversation capability among users of IM system  10 . For example, two given users A and B may log on and be authenticated by IM system  10  (such as by providing a user ID and a password) and may begin using IM clients  100   a  and  100   b , respectively. In one embodiment, authentication of users and authorization of users to access resources provided by IM system  10  may be performed by IM server  140 , which may be configured to query directory server  150  to authenticate the identities of users A and B and determine their privileges within IM system  10 . IM client  100  may provide access for authenticated and authorized users to a directory service and may indicate to user A that user B is online and vice versa. For example, in one embodiment, IM client  100  may enable a given user to create customized lists of users and may display the status of each user specified in the list whenever the given user logs on to IM system  10  or requests such a display. IM client  100  may also provide a procedure for a given user to specifically query for the online status of another user, such as by providing that user&#39;s user ID. 
     Once user A has determined that user B is online, user A may direct IM client  100   a  to initiate a chat operation (also referred to herein as a chat session) with user B. In one embodiment, user A may then enter text via IM client  100   a  that may be forwarded to and displayed via IM client  100   b  for user B to read. User B may then enter response text via IM client  100   b  that may be forwarded to and displayed via IM client  100   a  for user A to read, thereby providing the aforementioned real-time conversation capability. Although the preceding description of chat session functionality includes only two participants, it is contemplated that a chat session may include an arbitrary number of participants. Also, in some embodiments, text may be sent from one IM client  100  to the IM clients  100  of other chat session participants immediately upon entry. In other embodiments, text may be held and displayed at the IM client  100  at which it was entered until the user directs it to be sent, such as by entering a carriage return or invoking a “send” feature. Such an embodiment of IM client  100  may thereby enable chat session users to edit their input prior to making it visible to other participants. 
     In addition to indicating whether or not a given user is online within IM system  10 , IM client  100  may implement and display a presence state for a user. In one embodiment, presence state may comprise a state indicative of the presence or absence of a given instant messaging user, as well as any additional available information about that&#39;s user&#39;s current activity. In some embodiments, presence state may include textual information such as “online,” “busy,” “away,” “be right back,” “on the phone,” “out to lunch,” and “gone home.” In some embodiments, other default presence states may be defined and users may be able to create new presence states. It is also contemplated that in some embodiments, a presence state may include numeric codes or encrypted values. 
     In one embodiment, a given user may manually select a particular presence state value from a menu, list, or other selection mechanism, and the selected presence state may then be displayed to other users of IM system  10  whenever they query the status of the given user. For example, user A may select the “away” presence state in IM client  100   a . If user A is in user B&#39;s customized list of users of IM system  10 , IM client  100   b  may show the “away” presence state associated with user A whenever user B views the list. Alternatively, IM client  100   b  may show the “away” presence state associated with user A if user B specifically queries the status of user A within IM system  10 , such as by providing user A&#39;s user ID. User B may then utilize the presence state of user A in determining whether to initiate or respond a chat session request with user A. As described in greater detail below, the presence state of a given user may change in response to events other than manual selection by that user, and changes in presence state may result in actions beyond simply displaying that user&#39;s presence state to other users of IM system  10 . 
     In some circumstances, user A of IM system  10  may wish to communicate information to user B without expecting a response from user B. Rather than attempt to establish a chat session in this case, user A may send an alert to user B using an alert operation. In one embodiment, the alert operation may provide a unidirectional communication capability among users of IM system  10 . For example, in a manner similar to that illustrated in the exemplary chat session described above, user A may determine whether user B is online. After making this determination, user A may enter the information to be sent to user B via IM client  100   a , and may then direct IM client  100   a  to send an alert to user B. Alternatively, user A may send the alert without determining whether user B is online, whereupon IM system  10  may queue the alert for later delivery to user B if user B is currently offline. If user B is online, upon receiving the information in the alert IM client  100   b  may then display the alert for user B. For example, in some embodiments IM client  100   b  may generate a visual and/or audible indication that an alert has arrived and may cause the information content of the alert to be displayed on a video display device or played audibly via an audio system. Once user B has acknowledged the alert, IM client  100   b  may notify IM client  100   a , which may in turn display to user A a notification (such as a text message, for example) that user B has received and acknowledged the alert. 
     In some embodiments, alerts may originate from sources other than individual users of IM system  10 . For example, a given user may customize an email application to send an alert to the IM client  100  of that user whenever an email message arrives for that user. Alternatively, a calendar application may be configured to send an alert when particular calendar appointments come due. 
     A polling operation may provide a mechanism for a given user to solicit responses from other users of IM system  10  without establishing a chat session with each solicited user. In one embodiment, the polling operation may provide a bidirectional question-and-response communication capability among users of IM system  10 , wherein a given user (referred to herein as the respondent) may formulate a question to be directed to other users (referred to herein as the recipients) along with a list of possible responses to the question. Upon receiving the poll, each recipient may select a particular response and send the selected response to the respondent. In one embodiment, the polling operation may support “write-in” responses that may allow recipients to specify a response other than those listed in the poll. 
     For example, the respondent may enter a polling question as well as a list of possible responses via IM client  100   a , and may further select the recipients from the users of IM system  10  by using a directory service or a predefined list of users as described above. The respondent may then direct IM client  100   a  to send the poll to the specified recipients. The recipients may receive the poll via their respective IM clients  100 , which may display the polling question and responses in a manner similar to displaying an alert as described above. Each recipient may then select a response and direct his or her respective IM client  100  to send the selected response to the respondent. IM client  100   a  may receive and display responses to the respondent, and may also indicate which recipients have and have not responded to the poll. 
     A news channel operation may provide a mechanism for a given user to disseminate information to other users of IM system  10  without establishing a chat session with each other user or sending an alert or poll to each other user. In one embodiment, the news channel operation may provide a forum, referred to herein as a news channel, for users to post and read information. In such an embodiment, a given news channel may be static, in that information posted to it may remain available to be read until it is explicitly deleted or until it expires. A news channel may thereby provide an asynchronous communication mechanism in which users may exchange information without simultaneously actively using IM system  10 . As an example, a given user may use IM client  100   a  to compose information, such as text information, to be posted to a particular news channel specified by the user. That user may then direct IM client  100   a  to post the information to the specified news channel and may optionally specify a date and/or time when the posting should expire. Other users may subsequently direct their respective IM clients  100  to view the contents of the particular news channel and may compose and post their responses or other information. 
     In some embodiments of IM system  10 , some instant messaging operations described above as well as some sub-operations of those operations may not be available to all users of the system. For example, in one embodiment, certain news channels may only be accessed for reading by a specific group of users, and only a subset of that group may be allowed to post content to those news channels. Similarly, some users may be restricted from establishing chat sessions or sending alerts to other users. In such embodiments, privileges to use various features and operations of IM system  10  may be assigned to individual users. In one embodiment, IM server  140  (described below) may be configured to manage user privileges and control access to features and operations of IM system  10  based on those privileges. 
     Instant Messaging System Software Modules 
     While in the above description of instant messaging operations IM client  100  may provide the most user-visible portion of these operations, in the embodiment of IM system  10  illustrated in  FIG. 1  numerous software modules may interact to support instant messaging functionality. 
     In the illustrated embodiment, IM clients  100   a  and  100   b  are configured as web-based clients associated with a respective web browser  100   a  or  100   b  rather than as standalone applications, although as noted below, in alternative embodiments IM clients  100   a  and  100   b  may be configured as standalone applications. A user may begin using a given web-based IM client  100  by navigating to a particular uniform resource locator (URL) identifying a path to the IM client software from within a corresponding web browser  110 . In one embodiment, web browser  110  may be a software application configured for accessing documents or applications over a network via a protocol such as hypertext transfer protocol (HTTP). For example, web browser  110  may be a software application such as Netscape Navigator™ or Netscape Communicator™, although in other embodiments different browser application software may be used. 
     Once a user specifies the IM client URL, for example by typing the URL into the appropriate input field of web browser  110 , in the illustrated embodiment web browser  110  requests and downloads IM resources  180  via web server  170 . In one embodiment, web server  170  may be a software application configured to deliver documents or applications to a web browser in response to a request. For example, web server  170  may be a software application such as Sun ONE Web Server, although in other embodiments different web server application software may be used. In the illustrated embodiment, IM resources  180  may include executable application code files, such as Java files, for example. When downloaded by and executed within web browser  110 , IM resources  180  may provide the software functionality of IM client  100 . For example, execution of IM resources  180  may cause an IM user interface to be displayed within web browser  110  or in a window separate from web browser  100 . It is noted that in some embodiments, web browser  110 , web server  170 , and IM resources  180  may all be located on and operate from a single computing device. In other embodiments, some or all of these software modules may be located on and operate from separate computing devices interconnected via a communication network such as an Ethernet network, for example. 
     Various IM clients  100  may communicate with one another to perform the chat, alert, poll, and/or news channel operations described above, as well as any other instant messaging operations that may be implemented in a particular embodiment. In the illustrated embodiment, communication among IM clients may take place through IM multiplexor  130  and IM server  140 . In one embodiment, IM server  140  may be a software application configured to control IM privileges and security, for example by limiting access to certain instant messaging operations by certain users of IM system  10 . IM server  140  may also store presence state data associated with each user of IM system  10  and make the presence state data visible to users that request it. 
     Additionally, IM server  140  may be configured to support the execution of the various instant messaging operations by IM clients  100 . For example, IM server  140  may establish chat operations by responding to a request to initiate a chat operation from one IM client  100 , locating the appropriate IM client  100  associated with the target user of the chat operation request, and notifying the latter IM client  100  of the chat operation request. In some embodiments, IM server  140  may be configured to mediate the subsequent exchange of data among the IM clients  100  participating in the chat session, while in other embodiments IM server  140  may be configured only to initiate the chat session, whereupon IM clients  100  may then directly communicate without server intervention. IM server  140  may also be configured to receive alert and poll operations originating from IM clients  100  and route such operations to the IM clients  100  of the appropriate users. Further, IM server  140  may be configured to receive and store messages destined for the various news channels that have been configured in IM system  10  and to deliver the contents of those news channels to IM clients  100  of requesting users. 
     In a given embodiment of IM system  10 , there may be numerous IM clients  100  that collectively generate numerous instant messaging operations to be serviced by a given IM server  140 . In some embodiments of IM system  10 , multiple instances of IM server  140  may be employed to ensure adequate system performance. Additionally, IM multiplexor  130  may be configured to consolidate multiple requests from IM clients  100  into a single communication stream such as a transmission control protocol (TCP) stream, which may then be sent to a given IM server  140  over a single communication port. Owing to the fact that in some embodiments, numerous IM clients  100  may be operating on numerous different computing devices, each of which may be connected to an IM server  140  via a communication network, interposing IM multiplexor  130  between IM clients  100  and a given IM server  140  may increase system performance by reducing the number of individual communication ports a given IM server  140  may need to service. 
     Prior to allowing an individual user to begin performing instant messaging operations via a given IM client  100 , IM server  140  may be configured to authenticate the user and to determine what privileges of IM system  10  operation that user may be entitled to. In the illustrated embodiment, IM server  140  may be configured to authenticate a given user by receiving a user ID and password from the IM client  100  associated with a user seeking to initiate instant messaging operations. IM server  140  may then consult a directory server  150  to determine whether the user ID and password combination is valid. In one embodiment directory server  150  may be a software application configured to store data regarding authorized users of IM system  10 , such as a user ID, full name, and contact information for a given user. In some embodiments, directory server  150  may implement the lightweight directory access protocol (LDAP), whereas in other embodiments directory server  150  may store user data using a different protocol. If directory server  150  confirms the validity of the user ID and password supplied by IM server  140 , IM server  140  may update the presence status of the user in question to reflect an online status and allow the user to proceed to initiate instant messaging operations. 
     In the illustrated embodiment of IM system  10 , IM server  140  may be configured to send email to users who are offline when an alert is directed to them. Specifically, IM server  140  may communicate with SMTP server  160  to provide the content and addressee information for such emails. SMTP server  160  may be a software application configured to process the sending and receiving of email. In one embodiment, SMTP server  160  may implement the simple mail transfer protocol (SMTP), although in other embodiments other protocols may be employed. In some embodiments of IM system  10 , the arrival of email destined for a given online user may trigger an instant messaging alert operation to that user. In such embodiments, IM server  140  may be configured to receive incoming email arrival information and to direct alerts to the appropriate IM clients  100  in response to such information. 
     In the illustrated embodiment, IM system  10  includes calendar server  190 . Calendar server  190  may be a software application configured to maintain schedule information for a given user of IM system  10 , where such schedule information may indicate an activity status of a given user at a given time of day. In one embodiment, calendar server  190  may be compliant with the Internet Calendaring and Scheduling Core Object Specification standard (RFC 2445), while in other embodiments, other standards may be employed. Schedule information may include the beginning and ending times of various events such as meetings, appointments, or other activity, for example. Schedule information may also include information about recurrence of events, locations, and contact information pertinent to a given event, as well as names of events and remarks pertaining to a given event. An activity status may include whether a user is free or busy at a particular time, and may additionally include more specific states such as, but not limited to, the presence states described above. As described in greater detail below, calendar server  190  may interact with IM clients  100  to modify presence state information based on schedule data. Calendar server  190  may also interact directly with IM server  140  on behalf of a user. It is noted that in some embodiments, IM system  10  may omit calendar server  190  while including other modules and functions such as those illustrated in  FIG. 1 . Additionally, in some embodiments IM system  10  may incorporate the functionality of calendar server  190  into a different software module, such as IM server  140 , for example. 
     It is noted that although the illustrated embodiment of IM system  10  depicts a web-based IM client application and a client-server IM system topology, alternative embodiments are contemplated in which different IM client application structures and different IM system topologies are employed. In one alternative embodiment, IM client  100  may be configured as a standalone application program rather than as a web-based application. In such an embodiment, IM client  100  may be invoked independently of web browser  110 , without downloading application code such as IM resources  180  via web server  170 . In another alternative embodiment, IM system  10  may be configured in a peer-to-peer topology rather than a client-server topology. In such an embodiment, the functions performed by IM server  140  as described above may be distributed among the IM clients  100  within the system. For example, rather than storing presence state information for users centrally within IM server  140  as in the client-server implementation, in one peer-to-peer embodiment a given IM client  100  may store presence state information for other IM clients  100  that are nearby (e.g., on the same portion of a network). In such a peer-to-peer embodiment, presence state changes and requests for presence state information may propagate from one IM client  100  to another. Further, in embodiments where the function of IM server  140  is distributed among IM clients  100 , IM multiplexor  130  may be unnecessary. Other embodiments of IM system  10  are possible and contemplated, including combinations of the aforementioned embodiments. 
     It is also noted that in some embodiments, various combinations of software modules illustrated as distinct in  FIG. 1  may be combined into one or more different software modules. It is further noted that the various software modules illustrated in  FIG. 1  may operate within a varying number of computer systems in different embodiments. For example, in one embodiment, each software module of the illustrated embodiment of IM system  10  may operate within a single computer system. In another embodiment, each of IM server  140 , directory server  150 , SMTP server  160 , and web server  170  may operate within a respective computer system, which systems may be interconnected via a communication network. Other such variations are possible and contemplated. 
     Referring to  FIG. 2 , a block diagram illustrating one embodiment of a system configured to execute instant messaging system software modules. Elements corresponding to elements of  FIG. 1  are numbered identically. System  12  includes a plurality of computer systems  20   a - f , which collectively may be referred to as computer system  20 . Each of computer systems  20   a - f  is coupled to interconnect medium  15 . 
     Each computer system  20  may be configured to execute software code such as the software modules of IM system  10  illustrated in  FIG. 1  and  FIG. 2 . Various embodiments of computer system  20  are described in greater detail below in conjunction with the description of  FIG. 3 . Interconnect medium  15  may be configured to transfer data among computer systems  20 . In some embodiments, interconnect medium  15  may be a wired communications medium such as an Ethernet, fiber optic, or telephony network, for example. In other embodiments, interconnect medium  15  may be a wireless communications medium such as, for example, a wireless 802.11 local area network (LAN) or a wireless telephony network (e.g., a cellular, PCS, or GSM network). It is contemplated that in some embodiments interconnect medium  15  may include multiple types of communications media and may represent the Internet or an intranet. 
     In the illustrated embodiment, computer system  20   a  is configured to execute directory server  150  as well as web browser  100   b  and IM client  100   b . Computer system  20   b  is configured to execute web browser  100   a  and IM client  100   a . Computer system  20   c  is configured to execute web server  170  and to serve IM resources  180 . Computer system  20   d  is configured to execute SMTP server  160 . Computer system  20   e  is configured to execute IM multiplexor  130  and IM server  140 , while computer system  20   f  is configured to execute calendar server  190 . In the course of executing its respective software modules, each computer system  20  may communicate with other computer systems  20  to perform the various IM system operations described above. For instance, when a user of computer system  20   b  wishes to initiate an IM session, computer system  20   b  may communicate with computer system  20   c  so that web browser  110   a  may obtain IM resources  180  via web server  170 . Additionally, computer system  20   b  may communicate with computer system  20   e  so that IM server  140  may authenticate and authorize the user. Computer system  20   e  may communicate with computer system  20   a  so that IM server  140  may obtain information regarding the user&#39;s identity from directory server  150 . 
     It is noted that in alternative embodiments, the illustrated software modules may be distributed differently among computer systems  20 . For example, server-type software modules may be configured to operate on a first set of one or more computer systems  20 , while client-type software modules (e.g. IM client  100  and web browser  110 ) may be configured to operate on a second set of one or more computer systems that is distinct from the first set. Additionally, in some embodiments each software module may operate on a respective computer system  20 , whereas in other embodiments multiple software modules may operate on a given computer system  20 . 
     Instant Messaging System Hardware 
     As noted above, the software modules comprising the illustrated embodiment of IM system  10  may be executed by one or more computer systems during operation of IM system  10 . Referring to  FIG. 3 , a block diagram of one embodiment of an exemplary computer system is shown. In the illustrated embodiment, computer system  20  includes processor  200  coupled to memory  210 . Both processor  200  and memory  210  are coupled to a variety of devices via input/output (I/O) subsystem  220 , including input device  230 , display device  240 , mass storage device  250 , and network interface device  260 . 
     Processor  200  may be configured to execute program instructions stored in memory  210  or received via I/O subsystem  220 . In one embodiment, processor  200  may be a microprocessor configured to implement a given instruction set architecture (ISA), such as the SPARC ISA or the x86 ISA, for example. In another embodiment, processor  200  may be a digital signal processor, while in still another embodiment, processor  200  may be an integrated device such as a microcontroller. In some embodiments, processor  200  may include an integrated memory controller (not shown) enabling it to couple directory to memory such as memory  210 , whereas in other embodiments, processor  200  may couple to memory via a separate interface (e.g., a north bridge) or via I/O subsystem  220 . 
     Memory  210  may be configured to store program instructions and data during operation of computer system  20 . In various embodiments, memory  210  may include any of a variety of memory technologies such as static random access memory (SRAM) or dynamic RAM (DRAM), including variants such as dual data rate synchronous DRAM (DDR SDRAM), error correcting code synchronous DRAM (ECC SDRAM), or Rambus DRAM (RDRAM), for example. Memory  210  may also include nonvolatile memory technologies such as nonvolatile “flash” RAM (NVRAM) or read-only memory (ROM). In some embodiments, it is contemplated that memory  210  may include a combination of technologies such as the foregoing, as well as other technologies not specifically mentioned. In the illustrated embodiment, memory  210  includes software code  215 , which may include program instructions and data corresponding to one or more of the software modules of IM system  10  of  FIG. 1 . Code  215  may also include program instructions and data corresponding to other application or operating system software modules. 
     I/O subsystem  220  may be configured to interface various peripheral devices to processor  200  and to memory  210 . In one embodiment I/O subsystem  220  may include logic and interconnect devices configured to implement a bus interconnect standard such as the peripheral component interconnect (PCI) bus standard, although in other embodiments other bus interconnect types or a combination of such types may be supported. In some embodiments, I/O subsystem  220  may include logic configured to support direct memory access (DMA) transfers between peripheral devices and memory  210 . 
     Input device  230  may be configured to receive input from one or more users of computer system  20  and to deliver such input to processor  200  and/or memory  210  via I/O subsystem  220 . For example, in one embodiment input device  230  may include tactile input devices such as a computer keyboard, a computer mouse, or a stylus/touchpad interface. Additionally, in one embodiment input device  230  may include video or audio input devices such as a video camera, a still camera, or a microphone, for example. In some embodiments, it is contemplated that input device  230  may include more than one input device, including other types of input devices. Input device  230  may also include hardware necessary to convert the format of the input data to the format required by computer system  20 . For example, input device  230  may include analog-to-digital processing hardware to convert audio or video input to a digital format. 
     Display device  240  may be configured to display output of computer system  20  to one or more users. For example, in one embodiment display device  240  may include a video display terminal such as a computer monitor or a liquid crystal display (LCD) screen, as well as a graphics processor configured to convert output data from the format produced by processor  200  to the format required by the display device. Display device  240  may also include audio output hardware or other output devices such as printers or plotters. In some embodiments, it is contemplated that display device  240  may include more then one display device, including other types of display devices. Further, in some embodiments a given device such as a touch screen, for example, may function as both an input device and a display device. 
     Mass storage device  250  may be configured to store data, including program instructions and data, for use during operation of computer system  20 . In one embodiment, mass storage device  250  may be both readable and writable, and may thereby be configured to store data produced by computer system  20  or received from input device  230  or another computer system. For example, mass storage device  250  may include a magnetic storage device such as a fixed disk drive (also referred to as a hard drive or hard disk), a removable magnetic disk drive, or a tape drive. Mass storage device  250  may also include a rewritable optical storage device such as a recordable or rewritable compact disk (CD-R or CD-RW) or a recordable digital video disk (DVD), for example. In other embodiments, mass storage device  250  may be a read-only optical device such as a CD-ROM or DVD-ROM. In still other embodiments, mass storage device  250  may be a solid-state storage device such as a removable flash RAM device, for example. In some embodiments, it is contemplated that optional mass storage device  250  may include more than one storage device, including other types of storage devices. 
     Network interface device  260  may be configured to transmit data from computer system  20  to other computer systems as well as to receive data from other computer systems via a communication network. In one embodiment, network interface device  260  may be physically coupled to one or more other computer systems and may implement a networking standard such as Ethernet, for example. Alternatively, network interface device  260  may implement a fiber optic communication network protocol, or it may implement a telephony protocol and function as a dial-up modem, for example. In another embodiment, network interface device  260  may use a wireless networking protocol to interface with one or more other computer systems, such as a wireless Ethernet protocol (e.g., Wi-Fi), the Bluetooth standard, or a wireless telephony standard. In some embodiments, it is contemplated that network interface device  260  may include more than one network interface implementing more than one type of interface protocol, including other types of devices and protocols. 
     It is noted that in some embodiments of computer system  20 , functions of various elements depicted in the embodiment of  FIG. 1  may be integrated into a single element. For example, in one embodiment, a microcontroller may integrate some or all of the functions of processor  200 , memory  210 , and I/O subsystem  220 . Alternatively, as noted above, in one embodiment input device  230  and display device  240  may be integrated into a single device, for example. Further, it is noted that in some embodiments, computer system  20  may omit one or more of input device  230 , display device  240 , mass storage device  250 , and network interface device  260 . 
     Various embodiments of computer system  20  may correspond to various types of well-known computing devices, depending on the configuration of the various components of computer system  20 . For example, an embodiment of computer system  20  that includes a high-performance processor  200 , a large quantity of memory  210 , a large quantity of hard disk storage as mass storage device  250 , and a high-bandwidth network interface device  260  may be configured to operate as a server computer system. Such a server computer system may further be configured to execute the server software modules of the IM system  10  embodiment illustrated in  FIG. 1 , as well as other software modules of IM system  10 . 
     In other embodiments, computer system  20  may be a desktop or portable computer system or a tablet computer system. A personal digital assistant (PDA) may be an embodiment of computer system  20  configured, for example, to include a touch screen and/or a voice recognition interface as input device  230 , a low-power-consumption processor  200 , flash NVRAM as memory  210 , and a wireless Ethernet interface (e.g., implementing the 802.11 “Wi-Fi” standard) as network interface device  260 . A wireless telephony device may also be an embodiment of computer system  20 . Various embodiments of such wireless telephony devices may include, for example, an analog or digital “cellular” telephone device implementing a wireless telephony standard such as GSM, TDMA, CDMA, or another standard. The aforementioned embodiments may be configured to execute software modules of the IM system  10  embodiment illustrated in  FIG. 1  such as IM client  100  and/or web browser  110 , as well as other software modules of IM system  10 . It is noted that numerous other embodiments of computer system  20  are possible and contemplated. 
     As noted above, in some embodiments code  215  may correspond to one or more of the software modules of IM system  10  illustrated in  FIG. 1 . In the illustrated embodiment of computer system  20 , code  215  resides in memory  210 . Memory  210  may be one embodiment of a computer-accessible medium configured to store program instructions and/or data such as included in code  215 . However, in other embodiments, the program instructions and/or data included in code  215  may be received, sent or stored upon different types of computer-accessible media. Generally speaking, a computer-accessible medium may include storage media or memory media such as magnetic or optical media, e.g., disk or CD-ROM included in some embodiments of computer system  20  as mass storage device  250 . A computer-accessible medium may also include volatile or non-volatile media such as RAM (e.g. SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc, that may be included in some embodiments of computer system  20  as memory  210 . Computer-accessible media that are capable of storing data, such as, e.g., any of the examples of physical media mentioned previously, may also be referred to as computer-accessible storage media. Further, a computer-accessible medium may include transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as network and/or a wireless link, which may be included in some embodiments of computer system  20  as network interface device  260 . 
     Changing Instant Messenger Presence State Based on Busy Detection 
     As described above, in some embodiments, IM system users may manually change the presence state associated with their respective IM clients to reflect an “away” presence status. For example, upon commencing a particular work activity, users may wish to indicate that they are unavailable to participate in instant messaging operations. Such users may then manually transition the presence state associated with their respective IM clients to an “away” presence state. The “away” presence state of such users may then be viewed by other IM system users. 
     In some embodiments, the presence state of an IM system user may be automatically transitioned to a busy state depending on some criterion. It is noted that in some embodiments, a busy presence state may be any IM presence state designated to represent busy status information. In one embodiment, a busy presence state may be a custom presence state defined by a given IM system user, such as “leave me alone,” for example. 
     In one embodiment, whether or not a given IM system user is busy may be associated with the activity of that user&#39;s computer system. For example, a high level of activity of input device  230 , such as keyboard or mouse activity, may indicate that a given user of computer system  20  is busy and that the presence state of that user should be transitioned to a busy state. Similarly, for example, if such a high level of activity is followed by a lower level of activity, this may indicate that the user is no longer busy and that the presence state of the user should be transitioned to an online state. It is noted that in some embodiments, an online presence state may be any IM presence state designated to represent online status information, where online status may represent a lower level of activity than that corresponding to a busy state. In one embodiment, an online presence state may be a custom presence state defined by a given IM system user, such as “I&#39;m free,” for example. Alternatively, if a high level of activity is followed by no activity, this may indicate that the user is no longer busy and that the presence state of the user should be transitioned to an idle state. It is noted that in some embodiments, an idle presence state may be any IM presence state designated to represent idle status information, and in one embodiment, an idle presence state may be a custom presence state defined by a given IM system user. 
     In one embodiment, a software module of IM system  10  of  FIG. 1 , such as IM client  100 , for example, may be configured to detect a computer system activity level, to determine whether that activity level exceeds an activity threshold, and to transition the presence state corresponding to a given user to a busy state in response to determining that the activity level exceeds the activity threshold. It is noted that in some embodiments, the computer system activity detected may occur on a computer system different from the one executing the software module configured to perform the detection. 
     In one embodiment, the computer system activity level may be a metric corresponding to an aspect of activity of computer system  20 . For example, in various embodiments, computer system activity may include keyboard activity, mouse activity, or processor utilization, and the corresponding computer system activity levels may be keyboard strokes per unit of time, mouse movements per unit of time, or the fraction of processor time spent performing operations other than idling, respectively. Processor utilization may further be segregated into utilization corresponding to foreground and background software processes, where in one embodiment, foreground software processes include processes a user is directly interacting with and background software processes include processes a user is not directly interacting with (such as batch jobs, for example). In one embodiment, computer system activity may also include instant messaging operations, such as chat sessions, where the corresponding activity level may include the number of simultaneous chat sessions a given user is participating in, for example. In other embodiments, other types and levels of computer system activity may be detected. It is noted that in some embodiments, the computer system activity to be detected may be configurable by a user. For example, a given user of IM client  100  may determine that the relevant computer system activities to be considered when determining whether to transition to a busy presence state include keyboard activity and processor utilization, but not mouse activity. The given user may then configure the appropriate activities to be detected, for example through a user interface provided by IM client  100 . 
     In one embodiment, IM client  100  may be configured to compare the detected activity level to a corresponding activity threshold to determine whether the activity threshold has been exceeded. In one embodiment, IM client  100  may make this determination at a single point in time, whereas in another embodiment, IM client  100  may include a threshold time parameter corresponding to a given activity level and may require the activity level to exceed the activity threshold for at least the threshold time before determining that the activity threshold has been exceeded. In one embodiment, the various activity thresholds and corresponding threshold times may be parameters configurable by a user of IM client  100 . For example, IM client  100  may provide a user interface through which a user may specify which activities are to be detected, as well as what thresholds correspond to the specified activities. As a specific example, a user may select that keyboard activity should be detected with an activity threshold of  50  keystrokes per minute and a threshold time of three minutes and that foreground processor utilization should be detected with an activity threshold of 60% and a threshold time of five minutes. 
     In one embodiment, IM client  100  may be configured to transition the presence state corresponding to a given user to a busy state in response to determining that the detected activity level exceeds the corresponding activity threshold. In such an embodiment, IM client  100  may further be configured to determine whether the detected activity level does not exceed the corresponding activity threshold and to transition the presence state to an online state in response to this determination. In one embodiment, IM client  100  may further be configured to determine whether no activity has been detected and to transition the presence state to an idle state in response to this determination. IM client  100  may employ respective threshold times for online state determination and idle state determination that in various embodiments may be the same parameters as that used for busy determination, or separate parameters. 
     It is noted that although in one embodiment, busy status detection and corresponding presence state transitioning have been described as aspects of IM client  100 , in other embodiments, it is contemplated that these functions may be implemented in other software modules of IM system  10  in various embodiments as noted above. It is further noted that in some embodiments, these functions may be implemented as program instructions and/or data of a computer-accessible medium as described above. 
       FIG. 4A  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during processing of presence state using computer system activity information. Operation begins in block  300 , where a computer system activity level indicative of computer system activity is detected. In one embodiment, a software module such as IM client  100  of  FIG. 1 , for example, may be configured to perform computer system activity level detection, as described above. Also, in one embodiment, the computer system exhibiting the detected activity may be a system such as computer system  20  of  FIG. 3 . In various embodiments, the types and levels of computer system activity detected may be those described above, including, for example, keyboard, mouse, processor (including foreground and background process activity), and instant messaging operation activity. Additionally, as noted above, the computer system activity detected may be configurable by a user. 
     In response to detecting computer system activity, the instant messaging system may determine whether the detected activity level exceeds an activity threshold (block  302 ). Activity threshold types may be as described above, and in some embodiments may be configurable by a user. In one embodiment, determining whether the detected activity level exceeds an activity threshold may include determining whether the duration of the detected level of activity exceeds a threshold time. In some embodiments, as noted above, the threshold time may be configurable by a user. 
     In response to determining whether the detected activity level exceeds an activity threshold, if the threshold is not exceeded, no action may be taken (block  304 ). If the threshold is exceeded, the instant messaging system may transition the presence state corresponding to a given user to a busy state (block  306 ). In another embodiment, operation may optionally continue from block  306 , as described below. 
       FIG. 4B  is a flow diagram illustrating the operation of a second embodiment of an instant messaging system during processing of presence state using computer system activity information. The operation illustrated in  FIG. 4B  represents a continuation of the operation illustrated in  FIG. 4A . Specifically, operation begins subsequent to block  306  of  FIG. 4A , where the instant messaging system has transitioned the presence state corresponding to a given user to a busy state. In block  308 , subsequent to transitioning the presence state to the busy state, the instant messaging system may determine whether the detected activity level does not exceed the activity threshold. In one embodiment, determining whether the detected activity level does not exceed an activity threshold may include determining whether the duration of the detected level of activity exceeds a threshold time, which time may be the same value as or a different value from the time referred to in block  302  of  FIG. 4A . In an alternative embodiment, the instant messaging system may distinguish between whether the detected activity level does not exceed an activity threshold and whether no activity is detected. 
     In response to determining whether the detected activity level does not exceed an activity threshold, if the threshold is exceeded, no action may be taken (block  310 ). If the threshold is not exceeded, the instant messaging system may transition the presence state corresponding to a given user to an online state (block  312 ). In an alternative embodiment in which the instant messaging system distinguishes between whether the detected activity level does not exceed an activity threshold and whether no activity has been detected, the instant messaging system may transition the presence state corresponding to a given user to an idle state in response to determining that no activity has been detected. 
     Changing Instant Messenger Presence State Based on Schedule Information 
     As described above, in some embodiments IM system users may manually select a busy presence state, or such a presence state may be assigned by a respective IM client without a user&#39;s intervention in response to detecting various types of computer system activity. In addition to these techniques for changing presence state to a busy presence state, in some embodiments IM system users may manually select their presence state based on their schedule information. For example, at the beginning or end of a scheduled event such as a meeting, users may wish to indicate their activity status to others via their presence state. Such users may then manually transition the presence state associated with their respective IM clients to a presence state indicative of their activity status, such as “engaged,” “in a meeting,” “away from my desk,” or “available,” for example. In some embodiments, users may define custom presence states indicative of specific activity status information, such as “in the weekly sales meeting,” for example. 
     In one embodiment, the presence state of an IM system user may be automatically transitioned to a presence state corresponding to a given activity status depending upon that user&#39;s schedule information. For example, if a user stores schedule information in a calendar application accessible by the IM system, in one embodiment, the stored schedule information may be used to transition that user&#39;s presence state as his or her activity status, as indicated by the stored schedule information, changes throughout the day. 
     In one embodiment, a software module of IM system  10  of  FIG. 1 , such as calendar server  190 , for example, may be configured to store schedule information indicative of the activity status of corresponding users of IM system  10 . Additionally, a software module of IM system  10  such as IM client  100 , for example, may be configured to query the schedule information and to assign a presence state corresponding to the activity status indicated by a given user&#39;s schedule information, if the current presence state of that user does not so correspond. 
     In one embodiment, calendar server  190  may be a calendar application program configured to store schedule information indicative of a user&#39;s activity status. For example, calendar server  190  may be configured to store start and end times of various scheduled events occurring throughout a user&#39;s day. In some embodiments, calendar server  190  may also be configured to store additional information regarding scheduled events such as the name of the event, its location, and the identities of other attendees, for example. In some embodiments, calendar server  190  may make a given user&#39;s schedule information visible to other users for reading and/or modification. For example, calendar server  190  may allow one user to add events to another&#39;s schedule information, such as when scheduling a meeting. In some embodiments, calendar server  190  may require authentication and authorization of a given user prior to allowing the given user to access his or her own schedule information or the schedule information of another user. In such embodiments, authentication and authorization may be performed directly by calendar server  190  or by another module of IM system  10  such as IM server  140 , for example. Further, in some embodiments directory server  150  may be employed to assist in authentication and authorization of users of calendar server  190  in a manner similar to that described above for the general case of IM user authentication. 
     In one embodiment, calendar server  190  may be configured to respond to queries for schedule information corresponding to a given user, thereby making schedule information available to other applications. In one embodiment, calendar server  190  may be compliant with the Internet Calendaring and Scheduling Core Object Specification (also referred to as RFC (Request for Comments)  2445 ), a standard specifying a format for data exchange with calendar applications, although in other embodiments, a different standard for data exchange may be employed. In one embodiment, calendar server  190  may be accessible for queries as a web application via a uniform resource locator (URL) or “web address,” although in other embodiments, calendar server  190  may be accessible via a different interface. 
     In response to a query for schedule information of a given user, in one embodiment calendar server  190  may return an indication of free (i.e., available) or busy (i.e., engaged) activity status of that user. For example, if there is any scheduled event at the time specified in the query, calendar server  190  may return an indication of engaged activity status. Otherwise, calendar server  190  may return an indication of available activity status. In another embodiment, calendar server  190  may return more details about a given user&#39;s schedule information instead of or in addition to an indication of available or engaged activity status. For example, if there is any scheduled event at the time specified in the query, calendar server  190  may return the name of the event, its location (if known), and its duration. 
     In one embodiment, a given IM client  100  may be configured to query calendar server  190  for the schedule information corresponding to the user associated with the given IM client  100 . The activity status indicated by the schedule information returned by calendar server  190  may not correspond with the current presence state of the user associated with the given IM client  100 . If the current presence state does not correspond to the indicated activity status, in one embodiment, IM client  100  may be configured to assign a different presence state that does correspond to the indicated activity status. For example, the current presence state of the user may be idle or online, but at the queried time, a scheduled meeting may have begun, and calendar server  190  may have returned an engaged activity status. Correspondingly, IM client  100  may assign an engaged presence state in response to the schedule query. Conversely, the current presence state of the user may be engaged, but at the queried time, a scheduled meeting may have ended, and calendar server  190  may have returned an available activity status. Correspondingly, IM client  100  may assign an idle or online presence state in response to the schedule query. Alternatively, IM client  100  may store the presence state of the user prior to the beginning of a scheduled event, and may return the presence state of the user to the stored state after the scheduled event ends. 
     In an alternative embodiment, calendar server  190  may return more detailed schedule information instead of or in addition to an indication of available or engaged activity status, as described above. In such an embodiment, if the current presence state does not correspond to the indicated activity status, IM client  100  may be configured to assign a different presence state determined by the schedule information returned by calendar server  190  in response to the query. For example, prior to querying calendar server  190 , IM client  100  may indicate that the current presence state of the user is online. If at the queried time, the weekly sales meeting has begun, calendar server  190  may return the event title “weekly sales meeting” and a specific event end time, or other similar indications, in response to the schedule query. In response, IM client  100  may assign a presence state specific to the returned schedule information, such as “at weekly sales meeting” or “back at &lt;end time&gt;” where &lt;end time&gt; represents the event end time returned by calendar server  190 . 
     In one embodiment, IM client  100  may query calendar server  190  for a given user&#39;s schedule information periodically or aperiodically, using the current time at the time of each query as the basis for the query. Depending on the interval between queries, such an embodiment may approximate real-time synchronization of IM client  100  with calendar server  190 . In an alternative embodiment, IM client  100  may at a given time make multiple queries of calendar server  190 , each query for a different time. IM client  100  may then queue the query results internally and monitor the queue for activity status changes as current time progresses. Such an embodiment may enable IM client  100  to retain an indication of pending schedule information in case calendar server  190  is not continuously accessible, for example if the user disconnects a portable computer system from the network that provides access to calendar server  190  on a different computer system. In still another alternative embodiment, calendar server  190  may be configured to initiate a query of schedule information for a given user and to send the results of the query to the appropriate IM client  100  without waiting for a query to originate from IM client  100 . 
     It is noted that although in one embodiment, storage of schedule information and assignment of presence state based on such schedule information have been described as aspects of calendar server  190  and IM client  100  respectively, in other embodiments, it is contemplated that these functions may be implemented in other software modules of IM system  10  in various embodiments as noted above. For example, in one embodiment IM server  140  may interact directly with calendar server  190  to store a queue of schedule information on behalf of a given IM client  100 . It is also contemplated that in one embodiment, these functions may be combined in a single software module. It is further contemplated that in some embodiments, these functions may be implemented as program instructions and/or data of a computer-accessible medium as described above. 
       FIG. 5  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during processing of presence state using schedule information. Operation begins in block  400 , where schedule information corresponding to a given user and indicative of that user&#39;s activity status at a given time is stored. In one embodiment, a software module such as calendar server  190  of  FIG. 1 , for example, may be configured to store such schedule information, as described above. In various embodiments, the schedule information stored may be as described above, including, for example, a user identity, an event title, an event location, and event start and end times. 
     In block  402 , the stored schedule information is queried. In one embodiment, a software module such as IM client  100  of  FIG. 1 , for example, may be configured to query such stored schedule information, as described above. In another embodiment, a common software module may be configured to both store and query schedule information corresponding to a given user. Also, in one embodiment, calendar server  190  and IM client  100  may be configured to execute on one or more computer systems such as computer system  20  of  FIG. 3 . 
     In block  404 , in response to the schedule information query, if the current presence state of IM client  100  does not correspond to the activity status indicated by the schedule information for the given user, IM client  100  may assign a different presence state that corresponds to the activity status for the given user. As described above, in one embodiment, the current presence state may be transitioned to an engaged state in response to detecting an engaged activity status of the given user, and the current presence state may be transitioned to an online state in response to detecting an available activity status of the given user. In another embodiment, the current presence state may be transitioned to a state determined by the schedule information of the given user. For example, the schedule information may indicate an event title or location, and in one embodiment IM client may assign a corresponding presence state that includes some or all of such schedule information. 
     Linking Instant Messaging Operations to Presence State 
     The foregoing description illustrates how, in various embodiments, the presence state of an IM system user may be changed without that user&#39;s intervention based on such factors as computer system activity and user schedule information, for example. Even with these features, however, in some embodiments presence states and presence state transitions may function only as advisory indications. That is, the presence state of a given user may indicate state information to other users, but may not modify other users&#39; ability to engage in instant messaging operations with the given user. For example, if the given user&#39;s presence state changes to a busy state, either manually or without user intervention as described above, other users may not be prevented from sending alert operations or chat session requests to the given user despite the busy presence state. Additionally, in such embodiments, transitions from one presence state to another may have no particular significance in themselves, other than to advise that the given user&#39;s presence state has changed. 
     In one embodiment, instant messaging operations directed to a given user may operate selectively depending on the presence state of the user. For example, if a given user has a busy presence state, alert operations and chat session requests directed to the given user may be queued rather than delivered, thereby potentially eliminating the distraction of an instant messaging operation. In contrast, if the given user has an idle or online presence state, such alert operations and chat session requests may be processed and delivered normally. Additionally, in one embodiment, certain instant messenger operations may be associated with certain presence states for a given user, such that when the given user&#39;s presence state transitions to a new state, any instant messenger operations associated with the new state may be performed. For example, if a given user needs to perform a task before leaving on a particular day, an alert operation including a task reminder message may be scheduled for the particular day and associated with a “gone home” presence state. When the given user manually selects the “gone home” presence state, or alternatively when the user&#39;s calendar-based schedule information causes the “gone home” presence state to be selected as described above, the associated alert operation may be processed and delivered to the given user. 
     In one embodiment, a software module of IM system  10  of  FIG. 1 , such as IM client  100 , for example, may be configured to receive an instant messaging operation directed to a given user, determine the presence state of the given user, and to selectively process the instant messaging operation dependent upon the presence. Additionally, in one embodiment a software module of IM system  10  of  FIG. 1 , such as IM client  100 , for example, may be configured to store an instant messaging operation associated with a given presence state corresponding to a given user, detect a transition to the given presence state, and perform the instant messaging operation associated with the given presence state. 
     Processing Instant Messenger Operations Dependent on Presence State 
     In one embodiment, IM client  100  may be configured to receive an instant messaging operation directed to a given IM system user who is not offline. For example, a given IM client  100  may be configured to receive a chat, alert, or poll operation as  30  described above, although in other embodiments it is contemplated that additional or different operations may be received. The operation may be directed to a user who is online in IM system  10 , associated with the given IM client  100 , and whose presence state as indicated by the given IM client  100  is other than an offline presence state. In response to receiving the instant messaging operation, IM client  100  may be configured to determine the presence state of the user. Specifically, IM client  100  may determine that the presence state of the user is an idle presence state, an online presence state, or another presence state that may be indicative of an idle user state. Likewise, IM client  100  may determine that the presence state of the user is a busy presence state or another presence state that may be indicative of a busy user state. As noted above, in one embodiment a presence state may indicate a user&#39;s presence or absence as well as available information regarding that user&#39;s activity status. A user&#39;s activity status may also be referred to herein as a user state, and various presence states may be grouped according to user states the presence states may indicate. For example, “available” may be a presence state indicative of an idle user state, and “engaged” and “away” may be presence states indicative of a busy user state. 
     As noted above, IM client  100  may be configured to selectively process the received operation dependent upon the presence state of the user. In one embodiment, IM client  100  may be configured to notify the user of the received operation if the presence state of the user is indicative of an idle user state. For example, if the user has an online presence state and receives an alert operation, the alert operation may be processed normally, and the user may receive whatever alert notification the alert operation, such as a visual or audible notification. In such an embodiment, IM client  100  may be further configured to queue the received operation without notifying the user if the presence state of the user is indicative of a busy user state. In the example above, if the user has an engaged presence state and receives an alert operation, the alert operation may be queued without notifying the user with a visual or audible notification. Alternatively, the usual notification associated with the received operation may be modified in this case, such as by displaying a visual or audible notification of reduced intensity. In another embodiment, IM client  100  may be configured to selectively queue the received operation depending on other information pertaining to the operation. For example, IM client  100  may be configured to queue operations originated from certain users, while allowing operations originating from other users to notify the busy user, thereby providing the capability for the busy user to “screen” incoming operations. 
     In one embodiment, if an instant messaging operation initiated by a second user is queued in response to a busy user state of the intended recipient as described above, IM client  100  associated with the intended recipient may be configured to notify the second user that the operation was queued. For example, a second user may attempt to initiate a chat operation with a user having an engaged presence state. The chat operation may be queued at the IM client  100  of the busy user, which may send the second user a notification that the intended target of the chat operation is busy and/or that the chat operation has been queued. 
     In another embodiment, IM client  100  may be configured to detect a transition from a presence state indicative of a busy user state to a presence state indicative of an idle user state, and in response, to notify the associated user of queued instant messaging operations. For example, a user may manually transition his or her presence state from an away state to an online state, or such a transition may occur based on computer system activity status or schedule information as described above. Once the user transitions to an online presence state, queued operations may be delivered, for example in the order they were queued. 
     It is noted that although in one embodiment, selective processing of instant messaging operations dependent upon a given user&#39;s presence state has been described as an aspect of IM client  100 , in other embodiments, it is contemplated that this function may be implemented in other software modules of IM system  10  in various embodiments as noted above. It is further contemplated that in some embodiments, this function may be implemented as program instructions and/or data of a computer-accessible medium as described above. 
       FIG. 6  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during selective processing of instant messaging operations. Operation begins in block  500 , where an instant messaging operation directed to a given user who is not offline is received. In one embodiment, a software module such as IM client  100  of  FIG. 1 , for example, may be configured to receive such an operation, as described above. In various embodiments, such an operation may include a chat operation, an alert operation, a poll operation, or another instant messenger operation. 
     In response to receiving the instant messaging operation, the presence state of the given user to whom the received operation is directed is determined (block  502 ). In one embodiment, IM client  100  may be configured to determine the presence state of the given user. 
     In response to determining the presence state of the given user, the received operation is selectively processed dependent upon the presence state (block  504 ). In one embodiment, IM client  100  may select a particular action to take in response to the received operation, as described above. 
       FIG. 7  is a flow diagram illustrating the operation of another embodiment of an instant messaging system during selective processing of instant messaging operations. Operation begins in block  600 , where an instant messaging operation directed to a given user who is not offline is received. In one embodiment, a software module such as IM client  100  of  FIG. 1 , for example, may be configured to receive such an operation, as described above. In various embodiments, such an operation may include a chat operation, an alert operation, a poll operation, or another instant messenger operation. 
     In response to receiving the instant messaging operation, the presence state of the given user to whom the received operation is directed is determined (block  602 ). In one embodiment, IM client  100  may be configured to determine the presence state of the given user. 
     If the presence state of the given user is indicative of an idle user state, the given user may be notified of the received instant messaging operation, and the operation may be processed according to its specified behavior (block  604 ). For example, if the received operation is an alert operation, the given user may be notified of the alert operation. 
     If the present state of the given user is indicative of a busy user state, the received operation may be queued without notifying the given user (block  606 ). In one embodiment, IM client  100  may be configured to queue the received operation. In another embodiment, IM client  100  may be configured to notify a second user initiating the received operation of the queuing of the operation. 
     Subsequent to queuing of a received operation, a transition from a presence state indicative of a busy user state to a presence state indicative of an idle user state may be detected (block  608 ). In one embodiment, IM client  100  may be configured to detect such a transition. 
     In response to detecting such a transition, the given user may be notified of a queued instant messaging operation (block  610 ). In one embodiment, IM client  100  may be configured to notify the given user of queued operations, such as by delivering them in the order they were queued, for example. 
     Performing Instant Messenger Operations in Response to Presence State Changes 
     In one embodiment, IM client  100  may be configured to store an instant messaging operation associated with a given presence state corresponding to a given user. For example, IM client  100  may be configured to store a chat, alert, message or poll operation as described above, although in other embodiments it is contemplated that additional or different operations may be stored. The stored operation may be associated with a presence state such as an online presence state, for example. In one embodiment, IM client  100  may be configured to store sufficient information about the stored operation to enable the stored operation to be initiated. For example, if the stored operation is a chat operation, IM client  100  may store the identity of the user or the group of users to whom the chat operation is directed. In one embodiment, IM client  100  may maintain a plurality of queues in which to store instant messaging operations, with each queue associated with a respective presence state and configured to store operations associated with that presence state. For example, IM client  100  may maintain an online queue configured for storing operations associated with the online presence state, and a busy queue configured for storing operations associated with the busy presence state. In other embodiments, it is contemplated that the stored operations may be stored in different numbers and types of queues, or in data structures other than queues. Further, it is contemplated that in some embodiments another software module, such as IM server  140 , may be configured to maintain and monitor queues or other data structures that store instant messaging operations associated with a particular presence state on behalf of a given IM client  100 . 
     In one embodiment, IM client  100  may further be configured to detect a transition to a given presence state. For example, IM client  100  may detect a transition to an online presence state resulting from a user&#39;s manual selection or from processing computer system activity or schedule information without user intervention, as described above. In response to detecting the transition, in one embodiment IM client  100  may be configured to perform an instant messaging operation associated with the given presence state. For example, upon detecting a transition to an online presence state, IM client  100  may perform an operation stored in an online queue. 
     As a more specific example, a given user may wish to enter a particular chat session, such as a customer support chat session, whenever he or she is in an online presence state. The chat operation and information associated with the desired chat session, such as the identity of the customer support chat session, may be stored in the online queue of the given user&#39;s IM client  100 . Upon detecting a transition to an online presence state, the given user&#39;s IM client  100  may perform the queued chat operation, taking whatever steps may be necessary to place the given user in the customer support chat session. 
     Performing instant messaging operations in response to presence state changes may also incorporate schedule information from calendar server  190  described above. For example, a given user may wish to receive an alert as a reminder of a relative&#39;s birthday the first time the given user&#39;s presence state changes to online on or after the birthday. (Alternatively, the given user may wish to send an alert to the relative as a birthday greeting under the same circumstances.) In one embodiment, calendar server  190  may maintain schedule information regarding the birthday event and may store the alert operation, an effective date before which the operation should not be performed, and associated information, such as the identity of the user who is to receive the alert, in the online queue of the given user&#39;s IM client  100  on behalf of that user. Upon detecting a transition to an online presence state, the given user&#39;s IM client  100  may check the effective date of the queued alert operation. If the current date is equal to or later than the effective date, the given user&#39;s IM client  100  may perform the queued alert operation. In alternative embodiments, the stored alert could be associated with other presence states, such as the idle state, for example. 
     It is noted that although in one embodiment, performing instant messaging operations in response to presence state changes has been described as an aspect of IM client  100 , in other embodiments, it is contemplated that this function may be implemented in other software modules of IM system  10  in various embodiments as noted above. For example, this function may be implemented in IM server  140 . It is further contemplated that in some embodiments, this function may be implemented as program instructions and/or data of a computer-accessible medium as described above. 
       FIG. 8  is a flow diagram illustrating the operation of one embodiment of an instant messaging system during execution of instant messaging operations in response to presence state changes. Operation begins in block  700 , where an instant messaging operation associated with a given presence state corresponding to a given user is stored. In one embodiment, a software module such as IM client  100  of  FIG. 1 , for example, may be configured to store such an operation, as described above. In various embodiments, such an operation may include a chat operation, an alert operation, a poll operation, or another instant messenger operation. 
     Subsequent to storing the instant messenger operation, a transition to the given presence state may be detected (block  702 ). For example, in one embodiment IM client  100  may be configured to store a chat operation in a queue associated with an online presence state, and may subsequently detect a transition to an online presence state. 
     In response to detecting a transition to the given presence state, the stored operation may be performed (block  704 ). Referring to the above example, in one embodiment IM client  100  may be configured to initiate the chat operation stored in queue associated with an online presence state in response to detecting a transition to an online presence state. 
     It is noted that alternative embodiments employing combinations and aspects of the foregoing features are possible and contemplated. For example, in one embodiment, modification of a given user&#39;s presence state based on computer system activity or schedule information may be combined with processing of instant messenger operations dependent on that user&#39;s presence state or performing instant messenger operations in response to presence state transitions. In some embodiments, such combinations of features may be implemented in several software modules such as those illustrated in the embodiment of IM system  10  of  FIG. 1 . In other embodiments, such combinations of features may be implemented in a single software module, for example IM client  100  of  FIG. 1 . In some embodiments, such combinations of features may be implemented as program instructions and/or data of a computer-accessible medium as described above. 
     Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.