Patent Publication Number: US-2018046826-A1

Title: Dynamic enforcement of privacy settings by a social networking system on information shared with an external system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/581,786, filed on Dec. 23, 2014; which is a continuation of U.S. patent application Ser. No. 14/266,300, filed on Apr. 30, 2014 and issued as U.S. Pat. No. 8,955,145; which is a continuation of U.S. patent application Ser. No. 12/508,523, filed on Jul. 23, 2009 and issued as U.S. Pat. No. 8,752,186; each of which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to social networking and in particular to using information from a social network in an external system outside of the social network. 
     BACKGROUND 
     A system, such as a website, that allows users to interact with the system typically stores a record for each users of the system. These records may comprise information provided by the user as well as information gathered by the system related to activities or actions of the user on the system. For example, a system may require a user to enter information such as contact information, gender, preferences, interests, and the like in an initial interaction with the system, which is stored in the user&#39;s record. A user&#39;s activities on the system, such as frequency of access to particular information on the system, also provide information that can be stored in the user&#39;s record. The system may then use information provided by the user and information gathered about the user, to constantly customize interactions of the system with the user. For example, a website selling books may keep track of a users previous purchases and provide the user with information on related books during subsequent interactions with the system. Information in a user&#39;s profile may also be used by the system to target advertisements that are of interest to the user. Using information collected from and about users results in a system that is more efficient and beneficial for both the user and the system. 
     However, prior systems, including websites, lack the ability to use information associated with a user&#39;s social connections or activities to customize and/or personalize the user&#39;s experience while using the system. Access to information about the user&#39;s social interactions and/or the activities of a user&#39;s social connections (e.g. friends, family, co-workers, etc.) improves the user&#39;s experience while using the system and increases the chance that the user will use the system in the future. For example, users visiting a website that sells books may be interested in books that their social connections have looked at, book reviews or comments provided by their social connections, and other social information that might inform their purchases of book from the website. The system itself also benefits, because it can leverage information about the user and the user&#39;s social connections to more accurately determine what a user might be interested in. Such a system can use social information to customize a user&#39;s experience and target products, services and/or advertisements to the user. 
     Typical systems do not possess sufficient information about a user&#39;s social connections to customize the user&#39;s experience or effectively target advertising to the user. Assembling enough information about a user&#39;s social connections for these purposes requires a system to interact with a large number of users over an extended period of time. The majority of websites will not have the resources, expertise, or user base required to build and maintain a system of the scale necessary to capture, organize and maintain a sufficient amount of information about users&#39; social connections and their activities. Thus, users of these systems will have an inferior experience, and the customization/personalization provided by these sites is unlikely to accurately take into account or reflect information about the user&#39;s social connections and their activities. 
     A social networking system may establish privacy settings to allow users to decide who can access information associated with the user within the social networking system. Existing social networking systems enforce these privacy settings to control how information is used within the social networking system, but do not provide for enforcement of privacy settings outside the social networking system. A user who is not allowed to access particular information associated with another user within the social networking system should not be allowed to see the same information outside of the social networking system. When social network information is made available to external systems outside the social networking service, there are no existing techniques for enforcing the privacy settings established within the social networking service, outside that system on external systems. This is an even more difficult problem to resolve where privacy settings on the social networking system may be changed over time. 
     SUMMARY 
     To enforce privacy settings, which may change over time, embodiments of a social networking system maintain information related to actions of its users, where this information may be accessed and used by external systems. The social networking system enforces privacy settings that determine accessibility to information within the social networking system, as well as outside the social networking service. The privacy settings are enforced outside of the social networking system in the external systems. Embodiments of the invention propagate dynamic changes to the privacy settings within the social networking system to the external systems. 
     An embodiment presents a computer implemented method for sharing social network information with an external system subject to dynamic privacy settings. The social networking system maintains privacy settings containing rules for sharing social network information. A request for information associated with a user of the social networking system is received from an external system. A response to the request is determined and social network information is transmitted to the external system with the associated privacy settings for that information. In an embodiment, the response to the request comprises a subset of the requested information determined based on the privacy settings. When privacy settings are updated affecting one or more of the rules for sharing of social network information, the updates to the privacy settings are enforced in the external system by communications between the social networking system and the external system. In an embodiment, the communication is a message from the social networking system to the external system requesting the external system to cease using the information obtained in the previously transmitted response. In another embodiment, the social networking system and the external system have a previous agreement that the external system will use social network information for no more than a predetermined time period after receiving the social network information. In such an embodiment, the external system sends a request to the social networking system for updated information associated with the user when social network information is invalidated after the predetermined interval of time. 
     Another embodiment presents a computer implemented method for an external system to use social network information shared by a social networking system subject to dynamic privacy settings. An external system interacts with a user of the social networking service. If the external system wants social network information associated with the user of the social networking system, the external system sends a request to the social networking system. The external system&#39;s use of the information is governed by the privacy settings associated with the information it receives. If privacy settings are updated in the social networking system, the external system receives a communication from the social networking system. The information that has been received from the social networking system is then used in accordance with the updated privacy settings. In one embodiment, the communication received from the social networking system is a request to the external system to cease using the information provided by the social networking system. In another embodiment, the social networking system and the external system have previously agreed that the external system will use social network information for no more than a predetermined time period after it is received. 
     The features and advantages described in this summary and the following detailed description are not all-inclusive. Many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims hereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is high-level diagram illustrating how an external system can interact with a social networking system and client devices, in accordance with one embodiment of the invention. 
         FIG. 2  is an example diagram of privacy settings of a user of a social networking system, in accordance with one embodiment of the invention. 
         FIG. 3  is an interaction diagram of a process in which the social networking system actively invalidates information in an external system in response to changes to privacy settings, in accordance with one embodiment of the invention. 
         FIG. 4  is an interaction diagram of a process in which an external system refreshes information obtained from a social networking system after a pre-determined time interval in order to enforce updates to privacy settings, in accordance with one embodiment of the invention. 
     
    
    
     The figures depict various embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein. 
     DETAILED DESCRIPTION 
     External System Accessing Information from Social Network 
     A social networking system offers its users the ability to communicate and interact with other users of the social networking system. Users join the social networking system and then add connections to a number of other users to whom they desire to be connected. As used herein, the term “connection” refers to any other user (whether an individual or other entity) of the social networking system to whom a user has formed a connection, association, or relationship via the social networking system (connections may sometimes also be referred to as “friends”). Connections may be added explicitly by a user or automatically created by the social networking system based on common characteristics of the users (e.g., users who are alumni of the same educational institution). Connections in social networks can be one or two-way connections. For example, if Bob and Joe are both users and connected to each other in the website, Bob and Joe have a two-way connection. If Bob is interested in learning more information about Joe, but there is not a reciprocal connection, a one-way connection may be formed with Bob being connected to Joe, but Joe not being connected to Bob. The connection between users may be a direct connection; however, some embodiments of a social network allow the connection to be indirect via one or more levels of connections. The social networking system keeps a record of information for each user and the connections among the users. The record of users and their connections in the social networking system may be called a “social graph.” 
     Systems outside of the social networking system, called external systems, can access information available in the social networking system. Users of the external system can be users of a social networking system. The external system can access information from the social networking system using, for example, an Application Programming Interface (API) provided by or associated with the social networking system. The external system may use the information obtained from the social networking system for various purposes. A social networking system may interact with several external systems and information associated with a user of the social networking system can be fetched by or provided to multiple external systems. 
     The external system may store the information obtained from the social networking system to avoid sending a request to the social networking system repeatedly for the same information within a short interval of time. Privacy settings of the users may be enforced both by the social networking system when it responds to a request from the external system, and/or by the external system. In an embodiment, the social networking system enforces the privacy settings of the users when it responds to requests for information by providing the appropriate subset of the information in response. For example, the privacy settings of user A can specify that a profile image of user A is not accessible to user B even though users A and B are connected. If an external system requests profile images of friends of user B, the profile image of user A is not provided in the response. In another embodiment, the social networking system sends the requested information along with information about the privacy settings for that information, and the external system agrees or is required to enforce the privacy settings when using the information. For example, in the above example, the profile image of the user A is sent along with the privacy settings of user A for the profile image in response to the external system requesting profile images of friends of user B. The external system analyzes the privacy settings of user A and determines not to display the profile image of user A to user B in accordance with those privacy settings. 
     In some embodiments, the external system agrees to invalidate the social network information stored by the external system after a predetermined interval of time, for example, after 24 hours. If the external system needs the same set of information after the predetermined time interval, it sends a request to the social networking system even if it has a previously stored response to the request. This ensures that the external system receives the latest information and privacy settings available at the social networking system. For example, if the privacy settings of user A in the above example are updated to allow user B to access the profile image of user A, a response to a request from an external system obtained subsequently by the social network provides the updated information. However the change in the privacy settings or the change in any information available from the social networking system may not be reflected in the external system for the predetermined interval of time. For example, if the predetermined interval of time is 24 hours and the privacy settings of user B were updated soon after the external system fetched the profile images of the friends of user B, for 24 hours the user B may not be able to see the profile image of user A, even though user A has granted user B permission to view user A&#39;s profile image. 
     An embodiment alleviates the problem of the delay in propagation of changes from social networking system to external system by causing the social networking system to actively inform the external system in response to any updates to privacy settings or information of the social networking system that may affect data stored at the external system. For example, in response to the user A updating the profile settings allowing user B to view user A&#39;s profile image, the social networking system sends a message to the external system that has recently fetched the profile images of the friends of user A, requesting the external system to invalidate the data returned in the corresponding response. The external system sends a request to the social networking system if the corresponding data is needed by the external system. Accordingly, the external system may get the information from the social networking system that reflects the latest privacy settings much earlier than the predetermined time interval used by the external system for automatically invalidating its social network data. 
     In one embodiment, the latest privacy settings are sent to the external systems that are likely to use the information periodically. For example, a predetermined schedule is used to push privacy settings information to external systems. The privacy settings information may be pushed to the external system based on the predetermined schedule irrespective of whether any request is received from the external system and irrespective of any changes to the privacy settings. 
     System Architecture 
       FIG. 1  is a high level block diagram illustrating a system environment suitable for operation of a social networking system  120 . The system environment comprises one or more client devices  105 , one or more external systems  115 , a social networking system  120 , and a network  110 . In alternative configurations, different and/or additional modules can be included in the system. 
     The client devices  105  comprise one or more computing devices that can receive user input and can transmit and receive data via the network  110 . For example, the client devices  105  may be desktop computers, laptop computers, smart phones, personal digital assistants (PDAs), or any other device including computing functionality and data communication capabilities. The client devices  105  are configured to communicate via network  110 , which may comprise any combination of local area and/or wide area networks, using both wired and wireless communication systems. 
       FIG. 1  contains a block diagram of the social networking system  120 . The social networking system  120  includes a web server  150 , an API request server  170 , an authorization server  145 , an external system information manager  155 , a user profile store  160 , and a connection store  165 .  FIG. 1  also contains a block diagram of the external system  115 . The external system  115  includes a web server  125 , a content store  130 , a user accounts store  135 , a social network information manager  175 , and a social network data store  140 . In other embodiments, the social networking system  120  or the external system  115  may include additional, fewer, or different modules for various applications. Conventional components such as network interfaces, security mechanisms, load balancers, failover servers, management and network operations consoles, and the like are not shown so as to not obscure the details of the system. 
     The social networking system  120  comprises a computing system that allows users to communicate or otherwise interact with each other and access content as described herein. The social networking system  120  stores user profiles that describe the users of a social networking system, including biographic, demographic, and other types of descriptive information, such as work experience, educational history, hobbies or preferences, location, and the like. The social networking system  120  further stores data describing one or more connections between different users in the connection store  165 . The connection information may indicate users who have similar or common work experience, group memberships, hobbies, or educational history. Additionally, the social networking system  120  includes user-defined connections between different users, allowing users to specify their relationships with other users. For example, these user-defined connections allows users to generate relationships with other users that parallel the users&#39; real-life relationships, such as friends, co-workers, partners, and so forth. Members may select from predefined types of connections, or define their own connection types as needed. 
     The social networking system  120  stores information related to member actions on and/or off the social networking. Any action that a particular member takes with respect to another member is associated with each member&#39;s profile, through information maintained in a database or some other data repository. Such actions may include, for example, adding a connection to the other member, sending a message to the other member, reading a message from the other member, viewing content associated with the other member, attending an event posted by another member, among others. In addition, a number of actions described below in connection with other objects are directed at particular members, so these actions are associated with those members as well. 
     The web server  150  links the social networking system  120  via the network  110  to one or more client devices  105 ; the web server  150  serves web pages, as well as other web-related content, such as Java, Flash, XML, and so forth. In some embodiments, the web server may be used for communicating with the external system  115 . For example, requests sent by the external system  115  can be received by the web server  150  and processed. The web server  150  may include a mail server or other messaging functionality for receiving and routing messages between the social networking system  120  and the client devices  110 . The messages can be instant messages, queued messages (e.g., email), text and SMS messages, or any other suitable messaging technique. Embodiments in which the social networking system  120  is a website, the web requests are received by the web server  125 . However, in other embodiments, the input requests may be received by other modules, for example, the API request server  170 . 
     The API request server  170  allows external websites  200  to access information from the social networking system  120  by calling APIs. The API request server  170  may also allow external systems  115  to send information to social networking website by calling APIs  160 . An external system  115  sends an API request to the social networking system  120  via the network  110 . The API request is received at the social networking website by the API request server  170 . The API request server processes the request by calling the appropriate program code to collect any appropriate response, which is then communicated back to the external system  115  via the network  110 . 
     The authorization server  145  enforces the privacy settings of the users of the social networking system. The privacy setting of a user determines how particular information associated with a user can be accessed. The privacy setting comprises the specification of particular information associated with a user and the specification of the entity or entities with which the information can be shared. The entities with which information can be shared may include other users, applications, external systems, or any entity that can potentially access the information. The information that can be shared by a user comprises user profile information like profile photo, phone numbers associated with the user, user&#39;s connections, actions taken by the user such as adding a connection, changing user profile information and virtually any other information about the users actions or interactions on or associated with the social networking system or external systems. 
     The privacy setting specification may be provided at different levels of granularity. For example, the information to be shared may be specific information, such as, work phone number, or a set of related information, such as, personal information including several pieces of related information including profile photo, home phone number, and status. Alternatively, the privacy setting may apply to all the information associated with the user. The specification of the set of entities that can access particular information can also be specified at various levels of granularity. Sets of entities with which information can be shared may include, for example, all friends of the user, all friends of friends, all applications, or all external systems. One embodiment allows the specification to comprise an enumeration of entities, for example, the user may provide a list of external systems that are allowed to access certain information. Another embodiment allows the specification to comprise a set of entities along with exceptions that are not allowed to access the information. For example, a user of a social networking system may allow all external systems to access the user&#39;s work information but specify a list of external systems that are not allowed to access the work information. Certain embodiments call the list of exceptions that are not allowed to access certain information a “block list.” External systems belonging to a block list specified by a user of a social networking system are blocked from accessing the information specified in the privacy setting. Note that various combinations of granularity of specification of information and granularity of specification of entities with which information may be shared are possible, i.e., all personal information may be shared with friends, whereas all work information may be shared with friends of friends. Systems and methods for allowing an external system to access information in a social networking system using APIs that enforce privacy settings defined in the social networking system are disclosed in U.S. application Ser. No. 12/324,761, filed Nov. 26, 2008, which is incorporated by reference in its entirety. Systems and methods for allowing users to control accessibility of content in a social networking system is disclosed in U.S. application Ser. No. 12/485,856 filed on Jun. 16, 2009, which is incorporated by reference in its entirety. Systems and methods for providing privacy settings for applications associated with a user profile are disclosed in Ser. No. 12/154,886 filed on May 27, 2008, which is incorporated by reference in its entirety. 
       FIG. 2  illustrates an example of how the privacy settings of a user  260  of a social networking system control the accessibility of information associated with the user  260  to the user&#39;s connections  205  or to external systems  210 . The privacy settings can be defined for specific applications running either on the social networking system  120  or on external systems  115 . As shown in  FIG. 2 , the arrow  250  indicates that connection  205 (A) is allowed to access the work phone number  240  of user  260 , and arrow  255  indicates that connection  205 (A) is allowed to access the mobile phone number of the user  260 . Connection  205 (A) does not have access to information such as profile photo  215  of the user  260  or the user&#39;s friends list  225 . On the other hand, connection  205 (B) is allowed to access the user&#39;s friends list  225 . The information associated with a user includes actions taken by a user, such as the action of adding a new connection  230 . The user  260  can completely block another user, application or external system from accessing any information associated with the user  260 . A user or an application that is blocked by the user  260  does not have access to any information associated with user  260 . 
     The external system information manager  155  manages social network data that may be stored in external systems. For example, if privacy settings of a user are updated, the external system information manager  155  sends request to external systems to invalidate the related information that may be stored in the external systems. In an embodiment, the external system information manager  155  keeps data structures to track the external systems that accessed information from the social networking system  120  and the time when the information was accessed. The external system information manager  155  determines the information to be sent to the external system  115  to invalidate social network data stored at the external system  115 . For example, the external system information manager  155  may send a list of users to the external system  115  in order to invalidate information of those users. The external system information manager  155  may also send to an external system  115 , details of specific information that needs to be invalidated for a user. 
     The authorization server  145  contains logic to determine if certain information associated with a user of a social networking system can be accessed by a user&#39;s friends and/or other applications, entities or external systems. For example, an external system  115  that attempts to access a user&#39;s work phone number  240  must get authorization to access the information from the authorization server  145 . The authorization server  145  decides, based on the user&#39;s privacy settings, if the user&#39;s work phone number  240  can be accessed by the external system  115 . Based on the user&#39;s privacy settings, the authorization server  145  decides if the external system  115  is allowed to access information associated with the user  260 . 
     As discussed above, the social networking system  120  maintains data about objects with which a user may interact in the social networking system  120 . To this end, the user profile store  250  and the connection store  165  store instances of the corresponding type of objects maintained by the social networking system  120 . Each object type has information fields that are suitable for storing information appropriate to the type of object. For example, the user profile store  160  contains data structures with fields suitable for describing a user&#39;s profile. When a new object of a particular type is created, the social networking system  120  initializes a new data structure of the corresponding type, assigns a unique object identifier to it, and begins to add data to the object as needed. This might occur, for example, when a user becomes a user of the social networking system  120 , the social networking system  120  generates a new instance of a user profile in the user profile store  160 , assigns a unique identifier to the user profile, and begins to populate the fields of the user profile with information provided by the user. 
     The web server  125  of the external system  115  links the external system  115  via the network  110  to one or more client devices  105 ; the web server  150  serves web pages, as well as other web-related content, such as Java, Flash, XML, and so forth. The content presented to the client device  105  is stored in the content store  130 . In some embodiments, the web server  125  may be used for interacting with the social networking system. For example, requests and responses sent by the social networking system  120  can be received by the web server  125  for processing. Embodiments in which the external system is a website, the web requests are received by the web server  125 . However, in other embodiments, the input requests may be received by other modules, for example, the API request server  170 . 
     The external system  115  maintains a user accounts store  135  to maintain data associated with accounts of users of the external system  115 . The user accounts store  135  may store information associated with a user including user name and password as well as other information relevant to the external system  115 , for example, email address, mailing address, and billing information. In some embodiments, the external system  115  can also store information including actions or interests of the user. 
     The social network information manager  174  coordinates interactions with the social networking system  120  in order to obtain social network information from the social networking system  120 . The social network information manager  174  uses the APIs provided by or associated with the social networking system  120  for obtaining social network information. The social network information manager  174  processes messages sent by the social networking system, for example, messages requesting the external system  115  to invalidate certain social network information. The information obtained by the external system  115  from the social networking system  120  is stored in the social network information store  140 . The social network information store  140  also contains information regarding the time that the data was retrieved from the social networking system  120 . The time of retrieval of data is used to determine the time that has elapsed since the data was obtained from the social networking system  120 . The social network information manager  174  can invalidate data available in the social network information store  140  if a predetermined amount of time has elapsed since the data was obtained from the social networking system  120 . The social network information manager  174  may determine whether to use the data stored in the social network information store  140  or to refresh the data by sending a request to the social networking system  120 . 
     Enforcement of Privacy Settings of Social Networking System in an External System 
       FIG. 3  shows a process by which external system  115  accesses information associated with a user  300  from a social networking system  120  and illustrates how changes to the privacy settings of the user are propagated to the external system  115 . A user of the social networking system  120  becomes a user  300  of the external system  115  by either creating an account on the external system  115  or by simply interacting with the external system  115 . The process of  FIG. 3  starts with a user  300  of the external system  115  requesting  300  information from the external system  115 . The request  300  is received by the web server  125 .  FIG. 3  does not show certain steps that may happen before the user&#39;s request  300  to the external system  115 . For example, the user  300  may login to the external system  115  and take other actions before invoking the process that results in the requesting  300  of information from the external system  115 . In certain embodiments, the interaction  300  may correspond to the user taking any type of action on the external system  115 . To respond to the user&#39;s request, or to present the user with information that may be of interest to the user, the external system  115  determines  305  a need for information from the social networking system  120 , related to the user  300 . For example, a user may interact with a website for donating to a charity. The website may want to present to the user, a list of the user&#39;s friends that have donated at the website. Determining the list of user&#39;s friends requires the website to interact with the social networking system  120 . 
     The social network information manager  175  of the external system  115  requests  310  information associated with user  300  from the social networking system  120 . The external system  115  may or may not have the information regarding whether the user  300  is a user of the social networking system  120 . In case the external system  115  does not have information about whether the user  300  is a user of the social networking system  120 , the external system  115  may request the membership status of the user  300  in the social networking system  120 . If the external system  115  has the information that the user  300  is a user of the social networking system  120 , the external system  115  may request further information related to user  300  from the social networking system  120 . The additional information requested may comprise details of the user profile (including the users actions and interactions within and outside the social networking system) of the user or information related to the user&#39;s connections in the social networking system  120 . 
     As part of the request  310 , the social network information manager  175  of the external system  115  may present information associated with the user  300  that helps the social networking system  120  identify the user as a user of the social networking system  120 . The information presented by the external system  115  for identifying user  300  may depend on previous communications between the external system  115  and the social networking system  120  regarding the user  300 . For example, if the external system  115  has previously communicated with the social networking system  120  regarding user  300 , the social network information manager  175  may send a unique identifier associated with the user of the external system  120 , which may then be used to identify the corresponding user of a social networking system uniquely. If this is the first request sent by the external system  115  to the social networking system  120  regarding the user  300 , the social network information manager  175  may send information useful for identifying the user  300 . In one embodiment, the social network information manager  175  may uniquely identify the user  300  by sending information that it maintains for the user  300 , such as the user&#39;s full name, email address, home phone number, date of birth, or any other identifying information, alone or in combination. In one embodiment, the client device checks a session cookie associated with the social networking system  130  on the client device that indicates that the user is a member of the social networking system. Certain information associated with the user&#39;s account on the social networking system may be determined using session cookies set by the social networking system on the client device, for example, the user&#39;s login name. In another embodiment, the information gathered from the session cookies set by the social networking system is treated as preliminary information subject to further authentication and verification. For example, even though a session cookie may indicate that the user is a member of the social networking system, the user may be required to authenticate with a password to be able to access information from the social network system. Similarly, even though the session cookie may provide the login name of the user for the social networking system, further verification may be performed by sending a request to the social networking system since it is possible that the session cookies on the client device represent outdated information. 
     Once the request  310  is received by the API request server  170  of the social networking system  120 , in certain embodiments, the API request server  170  checks the user profile store  160  to determine whether the identification information presented with the request matches a user of the social networking system  120 . If the identification information matches a user of the social networking system  120 , the API request server  170  communicates with the authorization server  145  determine  315  the information to be returned to the external system  115  in response to the request  310 . If the requested information is associated with multiple users of the social networking system, the privacy settings of all the users involved are checked to compute the subset of information that the external system  115  is authorized to access. In one embodiment, the information returned to the external system  115  includes only the subset of information that the external system  115  is authorized to access based on the privacy settings of all the users whose information is requested. A user of a social networking system  120  who is not allowed to access certain information in the social networking system  120  is not allowed to access the same information when the social network information is presented to the user in an external system  115 . 
     If the external system  115  is authorized to access the requested information, API request server  170  of the social networking system  120  replies  320  to the external system&#39;s request  310  with the requested information. The processes of requesting  310 , determining  315  a response, and replying  320  may repeat several times, until the external system  115  has obtained the information that it needs for its own purposes. In an embodiment, the external system  115  then presents  330  this combined information to the user  300 . In another embodiment, the social network information is processed and combined with information available in the external system and sends the combined information to the client device  110 . In another embodiment, information obtained from the social networking system is not sent to the client device but instead used for processing to determine information that may be subsequently displayed to the user. In another embodiment, social networking system information may be used to determine whether specific content from the external system is displayed to the user or not. For example, the age of a user obtained from the social network may be used to determine of specific content can be displayed to the user or not. Alternatively, activities performed by the user in the social networking system may be used to determine the content displayed to the user. For example, a member active in particular social groups may be displayed content determined based on the members activities. 
     In an embodiment, instead of determining  315  a subset of the information based on the privacy settings, the API request server  170  of the social networking system  120  sends the relevant information needed to compute the subset along with the privacy settings information to the external system  115  in the reply  320 . The external system  115  ensures that the privacy settings are enforced when using the data and uses  325  the social network information accordingly. The external system  115  needs knowledge of how to enforce privacy settings of the social networking system  120 . In contrast, if the social networking system  120  computes the subset of information to be presented to the external system  115  based on privacy settings of the users of the social networking system, the external system  115  is not required to know how to enforce privacy settings. 
     The social networking system  120  may receive  335  an update to the privacy settings relevant to the user  300 . The update may be in response to the user  300  changing the privacy settings of the user  300 . For example, the user  300  may disallow the external system  115  from obtaining the status information of user  300  or the user  300  may allow the external system  115  access to certain information previously not accessible to the external system  115 . Alternatively, a connection of the user can change the connection&#39;s privacy settings, thereby changing the information that the user  300  is allowed to access. For example, if the user  300  was previously allowed to see the profile image of a connection, the connection can change the privacy settings to disallow user  300  from accessing the connection&#39;s profile image. The change affects the set of all profile images of connections that are accessible to the user  300 . A user can make changes to privacy settings affecting a specific user or to a set of users. For example, the user can make a change to a privacy setting applicable to a set of users listed with the change. Alternatively, a user can make changes to privacy settings affecting all the connections of the user. For example, a user can make the user&#39;s profile image inaccessible to all connections. In another embodiment, a user can make changes to privacy settings affecting all friends of friends. For example, a user can make the user&#39;s profile image accessible to all friends of the user as well as to all friends of friends of the user. A user can make a change to the privacy settings applicable to one or more external systems, thereby allowing or disallowing one or more external systems from accessing some information. A user can also make a change to the privacy settings applicable to one or more applications that may be running on the social networking system or on an external system. 
     Based on the scope of the change to the privacy settings, the external system information manager  155  of the social networking system determines  340  the impact of the change in terms of the various external systems affected by the change. For example, the external system information manager  155  may determine all the users affected by a change to privacy settings and determine all the external systems that need to be informed of the change to privacy settings. In an embodiment, the external system information manager  155  always sends a request to all external systems that access data from the social networking system to invalidate related data stored in the external systems. Accordingly, external systems that do not have any locally stored information that is affected by the changes to the privacy settings may also be informed of the change. As a result more requests  345  may be sent by the social networking system  120  than necessary. 
     In one embodiment, instead of sending  345  a message to invalidate information cached in the external system, the changes to the privacy settings are communicated to the external system. Accordingly, the external system receives the required information instead of having to send a subsequent request for information. However, the amount of data transferred to the external system in communicating the changed privacy settings may be more than the data communicated in a message that only invalidates information. This may cause higher communication overhead. Furthermore, it is possible that the external system never uses the privacy settings information communicated to the external system since the information was not communicated in response to a request but pushed to the external system. However in this embodiment, the external system receives the updated information as soon as changes occur to the privacy settings. The external system receiving the updated privacy settings information may be external systems that have previously requested the information or the information may be broadcast to all external systems. 
     In another embodiment, the external system information manager  155  tracks the users of the external systems that are users of the social networking system  120 . The external system information manager  155  sends  345  the request only to external systems that have at least one user that is a user of the social networking system  120  who is affected by the change  335  to the privacy settings. For example, if none of the users who are users of the social networking system  120  are affected by a change  335  to the privacy settings, there is no need to request  345  invalidation of information at the external system  115  since the external system  115  has no reason to locally store data related to the users of the social networking system affected by the change  335  to the privacy settings. 
     In another embodiment, the external system information manager  155  tracks the information that it sends  320  to external systems. The external system information manager  155  needs to request  345  invalidation of information at the external system  115  only if the external system  115  was previously sent  320  information affected by a change  335  of privacy settings. For example, the external system  115  may have users that are users of the social networking system  120  affected by the privacy settings change  335 , but if the external system  115  was never sent  320  any information affected by the change  335  of privacy settings, there is no reason to request  345  invalidation of information. In an embodiment, there is an agreement between the external system  115  and the social networking system  120  requiring the external system  115  to automatically invalidate any information sent  320  by the social networking system  120  after a predetermined interval of time, for example, 24 hours. The external system information manager  155  sends  345  requests for invalidation of information to an external system  115  if the social networking system  120  sent  320  any information affected by the change  335  of privacy settings within the predetermined time interval. If the predetermined time interval for the information affected by the change  335  of privacy settings has already expired, there is no need to request  345  invalidation of the information, because the external system  115  invalidates the information automatically based on the agreement with the social networking system. 
     There can be different levels of granularity of information that are invalidated by the request  345 . In an embodiment, the request  345  invalidates all the social network information stored in the external system. Accordingly, if the external system  115  subsequently determines  350  a need for social network information, it has to send a request  355  for information to the social networking system  120 . In another embodiment, the external system information manager  155  sends a list of users of the external system  115  with request  345 . The external system  115  invalidates all the information locally stored for the users in the list of users. If the external system  115  has locally stored information about users not affected by the change  335  to privacy settings, there is no need to invalidate that information since it is not affected by the change  335  to the privacy settings. In another embodiment, the external system information manager  155  sends  345  a list of users and the information to be invalidated for each user. This is useful if the amount of data stored for a user is large and requires significant amount of time to transfer from the social networking system  120 . For example, if the external system  115  has locally stored images of a user  300 , and the user updates privacy settings related to status of the user, there is no need to invalidate the images of the users stored in the external system  115 . Invalidation of all the information stored for user  300  may require transfer of large amount of data that was not specifically affected by the change  335  to the privacy settings. 
     In response to request  355 , the social networking system  120  determines  360 , based on the updated privacy settings, the information that needs to be sent to the external system  115 . The social networking system  120  replies with information based on privacy settings. In alternative embodiments, the social networking system  120  replies with the details of the updated privacy settings along with the information and users affected by the change  335  to the privacy settings, allowing the external system  115  to apply the privacy settings. The external system  115  uses  370  the information in accordance with the updated privacy settings. 
       FIG. 4  shows an interaction diagram of a process in which the external system  115  enforces updates to privacy settings by refreshing information obtained from a social networking system  120  after a pre-determined time interval. As compared to the embodiment disclosed in  FIG. 3 , the embodiment in  FIG. 4  does not require the social networking system  120  to send a message requesting  345  invalidation of information in response to changes  335  in privacy settings. The initial interactions shown in  FIG. 4  are similar to those shown in  FIG. 3 . As shown in  FIG. 4 , user  300  requests  300  information from the external system  115  and the external system  115  determines a need for social information  305  and requests  310  information from the social networking system  120 . The social networking system  120  determines  315  the subset of information to be sent to the external system  115  and replies  320  with the information. The external system  115  uses the  325  information received. 
     As shown in  FIG. 4 , in response to changes  335  in privacy settings the social networking system  120  does not send a request to the external system  115  to invalidate information. Instead, the external system  115  has an agreement with the social networking system  120  requiring the external system  115  to invalidate information received from the social networking system  120  after a predetermined interval of time since the receipt of the information. If the external system  115  needs social network information, the social network information manager  175  checks the social network information store  140  to determine if the information is already available locally. If the information required is available in the social network information store  140 , the social network information manager  175  checks if the information was retrieved from the social networking system  120  within the predetermined interval of time. If the information was not retrieved within the predetermined interval of time, the external system may expunge the social network information received previously. If the external system  115  needs the social network information after the predetermined interval of time, the external system  115  refreshes the required information by requesting  410  required information from the social networking system  120 . The social networking system  120  determines the subset of the information to be sent to the external system  115  based on the updated privacy settings and replies  420  with the information. The external system  115  uses  370  the information in accordance with the updated privacy settings. 
     In one embodiment, the privacy settings may be classified into privacy settings that need to be updated in external systems immediately and privacy settings that don&#39;t need to be updated in external systems immediately. For updates to privacy settings that need to be updated in external systems immediately, the social networking system  120  sends a request to the external system  115  to invalidate the associated information in response to changes to the privacy settings. For privacy settings that do not require an immediate update, the social networking system waits for the external system  115  to send a request after the information in the external system  115  is automatically invalidated by the external system  115  after a predetermined time interval from receipt of the information. 
     Alternative Applications 
     The foregoing description of the embodiments of the invention has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. 
     Some portions of this description describe the embodiments of the invention in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof. 
     Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described. 
     Embodiments of the invention may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a tangible computer readable storage medium or any type of media suitable for storing electronic instructions, and coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. 
     Embodiments of the invention may also relate to a computer data signal embodied in a carrier wave, where the computer data signal includes any embodiment of a computer program product or other data combination described herein. The computer data signal is a product that is presented in a tangible medium or carrier wave and modulated or otherwise encoded in the carrier wave, which is tangible, and transmitted according to any suitable transmission method. 
     Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.