Abstract:
A new system for communicating between computer programs is disclosed which includes a collaboration software program having a directory publishing procedure and a message forwarding procedure. In an example embodiment, the disclosed system provides a user of a network application program, such as an internet chat program, with an out-of-band mechanism to send invitations to other users of the network application program. A user of the network application program requests a list of all users known to the collaboration software program. The user list is for example a list of user names associated by the collaboration software program with URLs of home pages of users known to or registered with the collaboration software program. The user seeking to send the message then selects a user name and provides a message to the collaboration software program. The collaboration software program then posts the message so that the message can be displayed in the home page of the selected user. For example, the message is displayed in a screen within the window of the browser executing in a client system on which the selected user is working.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to communications between computer software programs implementing a restrictive security model and more specifically to a method and apparatus for synchronous communications between computer software programs which can be securely downloaded from web pages, such as Java™ applets. 
     BACKGROUND 
     The wide availability of the Internet permits an ever increasing number of users to download data from remote systems onto their local system. These actions are typically done through a browser software program which forms logical network connections with a remote system, and then uses the Hyper-Text Transport Protocol (HTTP) to move data from the remote system. The data may, for example, describe or consist of a set of Hyper-Text Markup Language (HTML) instructions. Such data frequently indicates or includes computer program code that is ultimately executed on the local machine. For example, the HTML instructions from a remote system may include indication of an “applet” program, written in the Java™ language developed by Sun Microsystems, Inc. 
     An applet is an example of a program which is typically embedded within a Web page, and which is executed when the Web page is browsed. Several restrictions apply to the design and operation of applets. Some of these restrictions relate to secure operation and execution of the applet on the client system. This arises from a concern most users have regarding the potentially devastating effects which can be caused by execution of poorly or maliciously designed code on their local system. The security restrictions imposed on applets have the result that applets loaded onto a local system from over the network cannot make network connections to hosts other than the host from which they are downloaded from. In addition, unsolicited information cannot be read from or written to the local computer system (hard disk) by an applet downloaded from a remote host. Moreover, applets have no capabilities for directly communicating with other applets. Because of these significant limitations, applets can generally be used for very little other than displaying data or managing user inputs. 
     Existing systems have thus been able to use applets in very limited ways. The above described restrictive security model for applets provided tight control over information flowing to and from applets, and thus allowed users to be assured that they were safe in loading applets down onto their local system for execution. However, several drawbacks result from the design and use of applets in existing systems. 
     First, existing systems do not permit a user of a first network application, for example a user of a chat room application, to communicate with another user who is not currently using that same network application, but who is currently running his or her local browser. In addition, existing systems provide no mechanisms for users of a network application, for example a shared whiteboard application, to determine whether or not applets are being run by other users that are potentially communicative with the applet of the local user. This is the consequence of preventing direct communication between applets. 
     For these reasons and others, it would be desirable to have a system which permits programs implementing a restrictive security model to communicate without otherwise compromising that security model. The new system shall allow such programs to communicate regardless of whether they were downloaded from a common network server, and further regardless of whether they are both currently running a common network application client. In addition, the new system should enable users to determine if other users are currently available for such inter-program communications. 
     SUMMARY 
     In accordance with principles of the invention there is disclosed a new system for communicating between computer programs. The disclosed system includes a collaboration software program having a directory publishing procedure and a message forwarding procedure. In an example embodiment, the disclosed system provides a user of a network application program, such as a chat program, with an out-of-band mechanism to send invitations to other users of the network application program who are not currently executing the network application program, but which are logged onto the network, for example through a browser program. The user of the network application program requests a list of all users known to the collaboration software program. The user list is for example a list containing user names associated with users known to or registered with the collaboration software program. The user seeking to send the message then selects one of the other users in the list and provides a message to the collaboration software program. The collaboration software program then maps the selected user name to a URL indicating a home page associated with the selected user name. The URL is for example mapped to the user name internally by the collaboration software program, thus eliminating the need for users to know each other&#39;s URLS. The collaboration software program then posts the message so that the message can be displayed in the home page of the selected user. For example, the message is displayed in a screen within the window of the browser executing in a client system on which the selected user is logged in. 
     In this way there is provided a new system which permits programs implementing a restrictive security model to communicate without otherwise compromising that security model. The new system allows such programs to communicate regardless of whether they were downloaded from a common network server, and further regardless of whether they are both currently running a common network application program. In addition, the new system enables users to determine if other users are currently available for such inter-program communications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing hardware and software elements of an example execution environment for the disclosed system; 
     FIG. 2 is a block diagram showing software elements in an example embodiment of a collaboration software server; 
     FIG. 3 is a block diagram showing elements in an example embodiment of a collaboration software system, a web browser, and a web server; 
     FIG. 4 is a block diagram showing elements in an example embodiment of a collaboration software client; 
     FIG. 5 is a block diagram showing the operation of the disclosed system; 
     FIG. 6 is a flow chart showing an example embodiment of steps performed by the disclosed collaboration software server; 
     FIG. 7 is a flow chart showing an example embodiment of steps performed by the disclosed client system to send a notification or invitation message; and 
     FIG. 8 is a flow chart showing an example embodiment of steps performed by the disclosed client system receiving a notification or invitation message. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now with reference to the elements of FIG. 1, there is described an example embodiment of the disclosed system for inter-program communications. FIG. 1 shows a Collaboration Software Client  38 , which may include one or more applets, and which may be downloaded, for example under control of a Web Browser program  39 , from a Server System A  10 . The Server System A  10  is described solely for purposes of example as including conventional computer hardware components on which is running a particular Web Server Program  25 . The Client System A  30  onto which the program is loaded includes for example conventional computer hardware components as well as the Web Browser  39 . Applets within the Collaboration Software Client  38  implement a security policy which prevents the applets from making a network connection, for example a socket connection under TCP/IP, with a system other than the Server System A  10 . The Collaboration Software Client  38  is for example embedded in a Web Page A  24  associated with a user of the Client System A  30 . 
     FIG. 1 further shows a second Collaboration Software Client  68 , for example including a number of applets, that is downloadable from a Server System B  42  to a Client System B  56 . The Client System B  56  is, for example, a second client system, distinct from Client System A  30  onto which the first program was downloaded. The applets within Collaboration Software Client  68  also implement a restrictive security policy which prevents the applets from making a network connection with a system other than the Server System B  42 . The Collaboration Software Client  68  is, for example, embedded in a Web Page B  48  associated with a user of the second Client System B  56 . 
     Now with reference to the elements of FIG. 2, a collaboration software program is further disclosed, which provides both a data repository and a directory publishing service. The collaboration software program for example includes a Collaboration Software Server  80  which includes a Data Repository  84 , and which builds user specific web pages in response to browser requests. The Collaboration Software Server  80  executes, for example, on the Server System A  10 , as shown in FIG.  1 . The Collaboration Software Server  80 , for example, corresponds to the Collaboration Software Server  28 , as shown in FIG.  1 . The collaboration software program further includes a number of client parts, for example capable of processing HTML and embedded applets, which execute on a number of client systems. 
     For example, the client parts of a collaboration software program are shown as Collaboration Software Client  38  and Collaboration Software Client  68 , as shown in FIG.  1 . In the example embodiment of FIG. 1, the Collaboration Software Client  38  and any applets it includes execute in the same execution context as the Web Browser  39 . Similarly, the Collaboration Software Client  68  and any applets it includes execute in the same execution context as the Web Browser  69 . 
     The Collaboration Software Clients  68  and  38  communicate with Collaboration Software Server  28  via in-band and out-of-band messages. For example, those messages sent using an established application layer protocol from one of Collaboration Software Clients  68  or  38  to a closely coupled sever application in an Application Layer  86  of the Collaboration Software Server  80  are “in-band” messages. For example, where the Collaboration Software Client  38  contains an internet “chat” client applet associated with an internet “chat” server application in the Application Layer  86  of the Collaboration Software Server  80 , those messages sent between that applet within the Collaboration Software Client  38  and the internet “chat” server application in the Collaboration Software Server  80  are considered to be “in-band” messages. Such in-band messages in the case of an internet “chat” client would then typically be forwarded by the internet “chat” server application to other internet chat clients. In an example embodiment, such in-band messages are sent directly from the Collaboration Software Client  38  to the application in the Collaboration Software Server  80  through a TCP/IP socket reserved for Internet Relay Chat (IRC). Further in the example embodiment, the established application layer protocol is an extended version of the conventional Internet Relay Chat (IRC) protocol as disclosed in RFC 1459, “Internet Relay Chat Protocol”, by Jarkko Oikarinen, May 1993. Accordingly, in the example embodiment, in-band messages support the Internet Relay Chat Protocol functions. Further in the example embodiment, the internet “chat” client applets are extended to provide additional in-band messages to support voting and whiteboard capabilities. 
     Out-of-band messages are not sent by the internet “chat” client applet within the Collaboration Software Client to the internet “chat” server application within the Collaboration Software Server  80 . Instead, the internet “chat” client applet within the Collaboration Software Client sends out-of-band messages to other applications in the Application Layer  86  of the Collaboration Software Server  86 . For example, the internet “chat” client applet sends two out-of-band messages: (1) an “invitation” message, and (2) an “request” message for obtaining a list of potential invitees. 
     The internet “chat” client sends the out-of-band request message to a predetermined application, for example indicated by the URL of that predetermined application, where the predetermined application is other than the internet “chat” server application, and where the predetermined application is within the Application Layer  86  of the Collaboration Software Server  80 . The URL of the predetermined application for example indicates a Collaboration Software Dispatcher (see FIG. 3) as well as the name of the predetermined application. The Collaboration Software Dispatcher processes the fields necessary to locate the predetermined application. Accordingly the URL is parameterized with the name of a predetermined application layer program in the Collaboration Software Server  80  that will return a list of users. 
     For example, in one embodiment, the code necessary to handle out-of-band messages is present in a number of applications within the Application Layer  86  of the Collaboration Software Server  80 . When the internet “chat” client is an applet and accordingly downloaded from a server system, it receives the location (URL) of one of those applications within the Application Layer  86 , based on the current display context of the client system. For example, where the current display includes in part a portion provided by one of the applications within the Application Layer  86 , then if an internet “chat” client is downloaded from the same server as the Collaboration Software Server  80 , the location (URL) of that one of the applications within the Application Layer  86  is downloaded with the internet “chat” client. 
     A Directory Publishing service is further shown included within the Collaboration Software Server  80 . The Directory Publishing Service  88  stores the names of users of client systems having collaboration software clients, such as Client System  30  and Client System  56  in FIG.  1 . When an application in the Application Layer  86  of the Collaboration Software Server  80  receives a request from an applet within a Collaboration Software Client, for example via a TCP/IP connection between a client system and the server, it uses the Directory Publishing Service  88  to provide a list of user names. In response to receipt of the list of user names from the directory publishing procedure, a display procedure within the requesting applet displays the list of user names through, for example, a dialog box. Then, by means of a user input procedure, the applet receives from the user of the client system indication of a selected one of the user names and a message to be sent to that user, for example, a user of a remote client system. 
     The disclosed system further includes an invitation message transmitting procedure, within for example the internet “chat” client applet, that transmits the inputted message, with the selected one of the user names to the Collaboration Software Server  80  of the collaboration software program. A message polling mechanism is included within a message posting applet, also within the Collaboration Software Client, for downloading an invitation message from the server part of the collaboration software program. 
     In the example embodiment of the Collaboration Software Server Part  80 , shown in FIG. 2, the Directory Publishing Service  88  is incorporated in a number of applications within an Application Layer  86 . Other example applications within the application layer of the Collaboration Software Server  80  (shown as Application  1   90  and Application  2   92 ) include for example a calendar application, a message filtering application, and a document publishing application. The calendar application for example permits users to enter a set of scheduled events, and then presents those events in a calendar format. One or more of the applications in the application layer of the Collaboration Software Server  80  are for example network application servers, and consists of a set of functions, each responding to a different user input. Each of the applications is modularly organized. 
     Further in the example embodiment shown in FIG. 2, the Data Repository  84  is shown for example as part of a tool kit layer. The Data Repository  84  shown in FIG. 2 is for example a built in database used to store various object instances. The example database is a relational model with an object hierarchy relationship facility available to those applications which require it. 
     Now with respect to FIG. 3, there is described an example of the Collaborative Software Server  80  operating in conjunction with a Web Browser  100  and a Web Server  102 . As is conventional, the Web Browser  100  submits requests to the Web Server  102  whenever a user opens a link. When the link points to a file, then the Web Server  102  sends the file to the Web Browser  100 . The link may also point to programs on a server; in that case, the Web Server  102  invokes the program and the program responds to the user. 
     In the example embodiment, when the link points to the Collaboration Software Server  80 , the Web Server  102  invokes a Dispatcher  108  through a Common Gateway Interface  106 . Based on the information passed along with the user request, the Dispatcher  108  invokes a specific application within the Collaboration Software Server  80 , which, in turn, calls various tools in the tool kit layer to respond to the user&#39;s request. 
     In the example embodiment, parameters are passed to the Dispatcher  108  within segments of a URL. The Dispatcher  108  parses the URL into pieces that provide the overall control of the program: (1) the name of the Collaboration Software Server  80 , (2) an access control area name, (3) a message name, and (4) some number of message arguments. In the example embodiment, each user registers once with an access control area. Based on the access control area name in the URL, the Web Server  102  knows where to find the user&#39;s credential for authentication purposes and also how to authenticate the user and pass the authenticated user identity to the Collaboration Software Server  80 . Given the user identity and the access control location, the Collaboration Software Server looks up the user profile, checks access control, and performs any other user specific functions. The message name and message arguments are then used by the Collaboration Software Server  80  to select particular actions to perform in one of the applications, for example as shown in FIG.  2 . 
     Now with reference to FIG. 4, there is described an example embodiment of a Collaboration Software Client  110 . The example Collaboration Software Client  110  is shown including a Directory Look-up Procedure  112 , which for example includes code portions for sending a message to the Collaboration Software Server  80 , for example using a Message Transmitter Code Portion  116 , wherein the message is either for or routed by one of the applications in the Application Layer  86  of the Collaboration Software Server  80 . The Collaboration Software Client  110  is further shown to include a Message Polling Mechanism  118 , for example within a Message Posting Applet, which receives messages received from the Collaboration Software Server  80 , for example through a pre-determined port or TCP socket. In an example embodiment, the Message Posting Applet receives messages from a variety of sources, and general purpose message posting facility. The Collaboration Software Client  110  supports and includes various other Applets  120 , Java Script and HTML portions  122 . 
     FIG. 5 shows an example of operation of a Collaboration Software Client  162 . A Collaboration Software Server  160  is shown, as well as Message Posting Applet  166  on a first Home Page  164  and Message Posting Applet  174  on a second home page  170 . A Collaboration Software Client  162  sends a request message to a dispatcher within the Collaboration Software Server  160 , which for example invokes another application using the Common Gateway Interface (CGI). For example the Collaboration Software Client  160  sends a request message through a TCP/IP socket with the server system. A Web Server program on the server system receives that message, which consists of a URL, and passes the message the the dispatcher based on the contents of the URL. The dispatcher examines the fields within the URL to determine a responding application within the Application Layer  161  of the Collaboration Software Server  160  to process the request message. 
     The responding application runs in the context of the Collaboration Software Server  160 , with access to all functions provided by the tool kit layer of the Collaborative Software Server  160 , as well as the Directory Publishing Service  88 . The responding application then calls the Directory Publishing Service  88 . The Directory Publishing Service  88  returns a list of users from its data repository. The responding application then returns the list of users to the Collaboration Software Client  162 . 
     Upon receipt of the list of users, an internet “chat” client applet within the Collaborative Software Client  162  displays the list of users. The user of the client system then indicates one of the users within the list. The internet “chat” client applet in turn sends an out-of-band invitation message via the dispatcher within the Collaboration Software Server  160 . The dispatcher determines an application within the Application Layer  161  of the Collaboration Software Server  160  to route the invitation message. For example, the same application within the Application Layer  161  is selected to route the invitation message as was selected to return the user list. 
     Within the Application Layer  161 , there is included a message store. The invitation message is initially routed by the application within the Application Layer  161  by adding the invitation message to the message store. Each message includes fields indicating what type the message is, for example an invitation to chat, as well as other information such as the subject of the proposed “chat session”, and a “chat channel” on which can be found the person sending the invitation to chat. 
     Message Posting Applets  166  and  174  periodically check the message store within the Application Layer  161  to determine if any new messages have been posted for their client. Messages which may be posted in the message store include chat invitation messages, collaboration software status, calendar event notifications, and inter-user messages. Each Message Posting Applet  166  and  174  includes a set of message filtering and display rules. The Message Posting Applet displays any new messages which satisfy its current filtering rules. For example, where the message is an invitation to chat, the Message Posting Applet may invoke a new internet “chat” client applet in response to a user input, for example in response to a double click on the displayed invitation. 
     FIG. 6 shows steps performed by an example embodiment of the disclosed system as shown in FIG.  5 . At step  200  a Web Server program receives a request message from the Collaboration Software Client and forwards it to the dispatcher within the Collaboration Software Server. At step  202  a responding application in the application layer of the Collaboration Software Server looks up a list of current users using the Directory Publishing Service. The responding application then sends the user list to the requesting client at step  204 . At step  206 , the Collaboration Software Server receives an invitation message from the client including an indicated one of the users in the list of current users. At step  208  a network application server within the Collaboration Software Server routes the notification message to the indicated user, for example by posting the message to a message store formed using the database functions provided by the tool kit layer within the Collaboration Server Software. 
     FIG. 7 shows steps performed by an example embodiment of the Collaboration Software Client  110  as shown in FIG.  4 . At step  210 , the Collaboration Software Client downloads a network application client for example including one or more applets such as an internet “chat” client applet. At step  212  the Collaboration Software Client sends a request message to the Collaboration Software Server. At step  214  the Collaboration Software Client receives a user list from the Collaboration Software Server, and displays the list of users. At step  216  the Collaboration Software Client inputs a selected user from the local user, for example by the local user double clicking on one of the users names in the displayed list of users. At step  218  the Collaboration Software Client sends a invitation or notification message through the Collaboration Software Server. 
     FIG. 8 shows the steps performed by an example embodiment of the Collaboration Software Client in response to receipt of a notification or invitation message. At step  220 , the notification is received. At step  222  the Collaboration Software Client displays a notification, for example through a dialog box presented by a message posting applet in the screen display of the local web-browser program. 
     While this invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.