Abstract:
A method includes receiving a request for a target Web page, the request containing a session identifier (ID) associated with an instance of a Web browser, and determining if the session ID is new or existing. If the session ID is new, the method includes creating a window session object, and initializing the window session object with data defining a state of the instance of the Web browser. If the session ID is existing, the method includes accessing a stored window session object using the session ID, the stored window session object containing data defining a state of the instance of the Web browser, generating the target Web page based on the data, and providing the target Web page to the Web browser.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 60/401,897, which was filed on Aug. 8, 2002. The contents of U.S. Provisional Application No. 60/401,897 are hereby incorporated by reference into this application as if set forth herein in full. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to maintaining independent states for multiple World Wide Web (“Web”) browser instances, such as browser windows. 
     BACKGROUND 
     HyperText Transfer Protocol (“HTTP”) is a stateless protocol. Web servers and Web browsers support “cookies”, which provide a state needed for a Web site. A cookie is a text file that a Web server sends to a Web browser, and that the Web browser returns to the Web server. The cookie contains state information relating to the Web browser. The Web server uses the state information to restore a previous state of a Web page on the browser. 
     Proxy servers or user preferences set in a Web browser can prevent the use of cookies. A technique for maintaining a Web browser state, which does not use cookies, is called “URL rewriting”. As background, each HTTP command contains a uniform resource locator (“URL”) and optionally some parameters. URL rewriting appends a session identifier (“ID”) to every URL contained in a Web page. The session ID identifies a session and thus state information associated with that session. The session ID may be returned to the Web server when a user clicks on any link in the Web page. The Web server uses the session ID to restore the state of the Web page to the browser. 
     Thus, both cookies and URL rewriting may be used to preserve a state of a Web page during browsing. But, if multiple browser windows are opened, the state is shared between windows. As a result, actions in one window will affect the other windows. This is because a Web browser can support cookies from a Web server, but not related to individual windows. URL rewriting has a similar limitation, because it is concerned with tracking a state of a user, not the state of a browser window. 
     By way of example, two Web browser windows may be opened to compare stock prices. Each window may display a stock “ticker”, which includes charts and date ranges. In conventional systems, changing a chart type or date range in one window will result in the same changes being made in another window when that other window is updated. 
     Having actions in one window affect states of other windows is not always desirable. 
     SUMMARY 
     In general, in one aspect, the invention is directed to a method of maintaining a state of an instance (e.g., a window) of a Web browser. The method includes receiving a request for a target Web page, where the request includes a URL-encoded session identifier (“ID”) associated with the instance of the Web browser, and storing a window session object associated with the session ID. The window session object contains data defining the state of the instance of the Web browser. 
     By storing window session objects, the foregoing method provides for independent tracking of Web browser instances in an HTTP session. Thus, changing the state of one Web browser instance in that HTTP session may not necessarily result in corresponding changes in state of other Web browser instances in that HTTP session. 
     This aspect of the invention may include one or more of the features set forth below. 
     Storing the window session object may include creating the window session object, and initializing the window session object with data. The window session object may be stored in association with an HTTP session object. The HTTP session object may contain state data that relates to an interaction between the Web browser and a Web site that contains the target Web page. 
     The request may be an HTTP command that is issued from an original Web page. The original Web page may contain a control feature that contains the session ID. The control feature may be used to issue the request for the target Web page. The control feature may be at least one of a menu item, a hyperlink, a button and/or an image. 
     This aspect may include receiving a request for a second Web page, where the request includes a URL-encoded second session ID associated with a second instance of the Web browser, and storing a second window session object associated with the second session ID. The second window session object may contain data defining the state of the second instance of the Web browser. 
     In general, in another aspect, the invention is directed to a method that includes receiving a request for a target Web page, where the request includes a URL-encoded session ID associated with an instance of a Web browser, and accessing a window session object using the session ID. The window session object contains data defining a state of the instance of the Web browser. This aspect also includes generating the target Web page based on the data, and providing the target Web page to the Web browser. 
     This aspect of the invention may include one or more of the features set forth below. 
     The request may be issued from an original Web page. The original Web page may contain a control feature that contains the session ID. The control feature may be used to issue the request for the target Web page. The control feature may be at least one of a menu item, a hyperlink, a button and an image. The request may be an HTTP command. 
     This aspect may also include determining if the session ID is a new or existing, and accessing the window session object only if the session ID is existing. The Web page may be generated by encoding URL(s) in the target Web page with the session ID, and/or encoding URL(s) in the target Web page that open additional instances of the Web browser with new, unique session IDs. 
     In general, in another aspect, the invention is directed to method that includes receiving a request for a target Web page, where the request contains a session ID associated with an instance of a Web browser, and determining if the session ID is new or existing. If the session ID is new, the method includes creating a window session object, and initializing the window session object with data defining a state of the instance of the Web browser. If the session ID is existing, the method includes accessing a stored window session object using the session ID, the stored window session object containing data defining a state of the instance of the Web browser, generating the target Web page based on the data, and providing the target Web page to the Web browser. 
     In general, in another aspect, the invention is directed to a method of storing HTTP session information. The method include storing a plurality of states within a single HTTP session. The plurality of states each corresponds to a window of a Web browser that has been opened during the HTTP session. The plurality of states each may correspond to a parameter in an HTTP command that identifies a window of the Web browser. 
     Other aspects of the invention are directed to apparatuses, systems, and articles of manufacture, such as readable media that store executable instructions, which are used to perform the methods described above. 
     Other features and advantages of the invention will become apparent from the following description, including the claims and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a network containing a server and a device, such as a computer; 
         FIG. 2  is a flowchart showing a process by which the server provides Web pages to the device; and 
         FIG. 3  shows an example of a monitoring system in which the process of  FIG. 2  may be implemented. 
     
    
    
     Like reference numerals in different figures indicate like elements. 
     DESCRIPTION 
       FIG. 1  shows a network  10 . Network  10  includes a device  11 . Device  11  may be any type of Web-enabled apparatus or system. Examples of such an apparatuses or systems include, but are not limited to, a desktop computer, a laptop computer, a cellular telephone, a personal digital assistant, and an embedded controller. 
     Device  11  may be connected to an internal network  12 , such as a local area network (“LAN”). A router or modem  14  may couple internal network  12  to an external network  15 , such as the Internet/World Wide Web. Alternatively, device  11  may be coupled directly to external network  15 . External network  15  runs Transmission Control Protocol/Internet Protocol (“TCP/IP”) or another suitable protocol. Network connections may be via Ethernet, telephone line, wireless, or other transmission media. 
     Device  11  contains a processor  17  and a memory  18  for storing software  20 . Processor  17  runs software  20 , which includes Web client application  21  and operating software. Web client application  21  includes a TCP/IP protocol stack that allows device  11  to communicate over external network  15 . The device operating software includes, but is not limited to, an operating system  13 , such as Windows XP®, and a Web browser  23 , such as Internet Explorer®. 
     External network  15  contains a server  19 , which may be a computer or any other type of processing device. Server  19  communicates with device  11  over external network  15  (and internal network  12 , if applicable). 
     Server  19  includes a controller  27 , such as a microprocessor, for executing software to perform the functions described below. The software may be stored in memory  24 , as shown in  FIG. 2 . 
     Server  19  executes Web server software  29  to communicate over external network  15 . Web server software  29  also generates and hosts Web pages. The Web pages (not shown) can be accessed and displayed via Web browser  23  on device  11 , as described in more detail below. 
     Web server software  29  may store data in, and retrieve data from, memory area  31 . Memory area  31 , which may be inside of (shown), or external to, server  19  stores HTTP session object  32 , which is associated with a user&#39;s HTTP session, and window session objects  34 , which are associated with instances (windows) of Web browser  23 . 
     HTTP session objects store state data for an entire interaction, i.e., HTTP session, between Web browser  23  and a Web site (comprised of multiple Web pages) hosted by server  19 . For example, HTTP session objects in an electronic commerce (“eCommerce”) site may store data that defines a shopping cart with products the user has selected from various Web pages. The HTTP session objects used herein also store a collection of named window session objects  34 . Window session objects  34  store state data that is associated with single instances (e.g., windows) of Web browser  23  during an HTTP session. Each window session object corresponds to a single Web browser instance. 
     In this context, “state data” refers, e.g., to identification and configuration data associated with a Web page. For example, a user may input information, such as an address, into a Web page. The user may also configure that Web page using configuration options available on the page. In this example, the address and configuration constitute the state data. It is noted that other types of state data may exist and that the processes described herein are not limited to use with any particular type of state data, including those noted-herein. 
     Generally speaking, HyperText Markup Language (“HTML”), i.e., Web, pages are created by servlets (in Java) running within Web server software  29 . The servlets also store the HTTP session objects to preserve browser states. Numerous servlets may make up an application, and they all may make use of stored HTTP session objects. Web server software  29  manages the HTTP session objects and provides mapping from a servlet to an individual HTTP session object session. This mapping may be performed using cookies or standard URL rewriting techniques. 
     Web server software  29  also includes a servlet  35 , which performs the process described below for maintaining independent states for browser instances/windows. 
     Maintaining Independent States For Browser Windows 
       FIG. 2  shows a process  40  for maintaining independent states for multiple Web browser instances using window session objects. In general, process  40  is a method of URL rewriting that identifies a browser window and compiles a collection of session objects that track each browser window state. A browser window identifier is then used to find and use related session information. As noted, in this embodiment, process  40  is performed by Web server software  29 , including servlet  35 . 
     Referring to  FIG. 2 , Web server software  29  publishes ( 42 ) a Web page (not shown). Servlet  35  incorporates, within the published Web page, control feature(s) that can be used to open new Web browser windows and, thus, new Web pages. The control feature may be, e.g., a menu item, a button and/or an image displayed on the Web page. Each control feature includes an embedded hyperlink, which is comprised of a URL and a session identifier (“ID”) parameter. The URL identifies the Web page to which the hyperlink refers. The parameter, which is written dynamically by servlet  35 , identifies a window session object associated with the Web page. 
     In this embodiment, the control feature has the following form: URL?window_id=3394, where “URL” is the URL of the Web page, and “window_id=3394” is the session ID parameter. Modifying a URL in this manner is known as “URL encoding”. The session ID parameter may be a numeric or alphanumeric string that uniquely identifies each Web browser window (instance) in an HTTP session. 
     A user at device  11  accesses the Web page published by Web server software  29  via Web browser  23 . When the user clicks on the control feature, a new Web browser window opens. The new Web browser window may be opened using a JavaScript function, such as “window.open( )”. This function requests a Web page using the Web page URL and a session ID parameter. The request for the Web page is sent from Web browser  23  to server  19  via external network  15 . In this embodiment, the request is an HTTP command that includes the Web page URL and the session ID parameter associated with the control feature. 
     Servlet  35  receives (43) the request from Web browser  23  and parses ( 44 ) the session ID parameter from the request. Servlet  35  determines ( 45 ) if the session ID parameter is new or existing within the current HTTP session object. Window session objects are indexed using their session ID parameters. Servlet  35  therefore searches through window session objects associated with the HTTP session object for the current HTTP session to locate the session ID parameter received (43) in the request. If the session ID parameter is found, then the session ID parameter is deemed to be existing in the current HTTP session; otherwise, the session ID parameter is new. 
     If the session ID parameter is new, servlet  35  creates ( 46 ) a new window session object and adds the new window session object to the collection of window session objects stored with the HTTP session object. The new window session object contains state data that defines the state of the instance of the Web browser from which the request was sent. Servlet  35  initializes ( 47 ) the window session object with state data for the Web browser window. The state data may be obtained from the Web browser window itself and/or from the HTTP session object. 
     Servlet  35  stores ( 48 ) the window session object in association with the current HTTP session object. As noted, the window session object is indexed using the session ID parameter. Look-up tables, for example, may be used to index the window session objects. 
     Referring back to block  45 , if the session ID parameter is determined to be existing, servlet  35  retrieves ( 49 ) data from the window session object that corresponds to the session ID parameter. In more detail, servlet  35  accesses the HTTP session object for the current HTTP session and searches the HTTP session object for the corresponding window session object using the session ID parameter. The data in the window session object provides the session state information that servlet  35  uses to create a Web page. Thus, if a Web page was requested with a specific session ID parameter, then all links on that Web page are rewritten to preserve the session ID parameter, i.e., all links are rewritten as “URL?window_id=3394”. This is know as URL encoding the links. 
     If any links on the Web page open yet another window, then they are rewritten with a unique and unused session ID parameter, which will become the session ID parameter of any newly created window(s). 
     As noted, the window session object contains session state information. This may include selected tabs and columns, search criteria, sort order, and which data set is viewed. Process  40  creates Web pages that preserve the session state information for each window of Web browser  23  in each Web page that it provides to that window. 
     Thus, process  40  is able to preserve the state of Web pages in different Web browser windows without affecting states of other Web browser windows in the current HTTP session. So, in process  40 , when search criteria for a data set in one Web browser window is entered, all other Web browser windows retain their own search criteria for their own corresponding data sets. 
     Once process  40  creates the Web page, process  40  sends ( 50 ) the Web page to Web browser  23 , where it is viewed in the appropriate Web browser window. 
     It is noted that process  40  may be repeated for multiple open Web browser windows. Thus, for another open Web browser window, process  40  receives a request for a second Web page. The request contains a second session ID parameter associated with a second instance of the Web browser. Process  40  stores a second window session object associated with the second session ID parameter. The second window session object contains data defining the state of the second instance of the Web browser. Data in the second window session object may be used to preserve the state of a browser window associated with that object, as described above with respect to process  40 . 
     Architecture and Alternative Embodiments 
     Process  40  is not limited to use with the hardware/software configuration of  FIGS. 1 and 2 ; it may find applicability in any computing or processing environment. Process  40  may be implemented in hardware (e.g., an ASIC {Application-Specific Integrated Circuit} and/or an FPGA {Field Programmable Gate Array}), software, or a combination of hardware and software. 
     Process  40  may be implemented using one or more computer programs executing on programmable computers that each includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and one or more output devices. 
     Each such program may be implemented in a high level procedural or object-oriented programming language to communicate with a computer system. Also, the programs can be implemented in assembly or machine language. The language may be a compiled or an interpreted language. 
     Each computer program may be stored on a storage medium or device (e.g., CD-ROM, hard disk, or magnetic diskette) that is readable by a general or special purpose programmable computer for configuring and operating the computer when the storage medium or device is read by the computer to perform process  40 . 
     Process  40  may also be implemented as a computer-readable storage medium, configured with a computer program, where, upon execution, instructions in the computer program cause the computer to operate in accordance with process  40 . 
     Device  11  can be included in a monitoring system  52 , such as that shown in  FIG. 3  and described in U.S. application Ser. No. 10/214,939, filed on Aug. 8, 2002, the contents of which are hereby incorporated by reference into this application as if set forth herein in full. 
     Monitoring system  52  includes sources  54   a ,  54   b  and  54   c , a network  55  (e.g., Internet), and Web browser  23  running on device  11 . Information may be sent from sources  54   a  to  54   c  through network  55  to device  11 . Sources  54   a  to  54   c  may include equipment (e.g., pumps, generators, etc.), databases that store collected data (e.g., sales, production numbers, etc.), applications servers, or any combination thereof. The information sent to device  11  may accessed by a user interface (“UI”), such as Web browser  23 , that has multiple windows to display information. The states of individual ones of these multiple windows may be preserved using process  40  of  FIG. 2 . 
     The invention is not limited to use with the protocols and standards described above. For example, process  40  is not limited to the block ordering show in  FIG. 2 . One or more of the blocks may be omitted or rearranged. Additional blocks, which contain additional process steps, may be inserted into the flow of  FIG. 2  Process  40  is not limited to the protocols and software described herein. Rather, process  40  may be implemented in any computing environment using different protocols or combinations of different protocols and those described herein. 
     Process  40  is not limited to providing a separate window session object for each Web browser window. Rather, groups of Web browser windows within a single HTTP session may be governed by a single window session object. In such an embodiment, changes in the state of a single Web browser window in the group may change the state of others in the group, but not affect the state of open Web browser windows outside the group but in the same HTTP session. 
     The invention is not limited to the Web browser state information described herein. The invention may be used with any type of state information or other type of Web browser configuration information. The invention also may be used outside the context of a Web browser and/or the Internet/World Wide Web. That is, the invention may be used with any type of windowing application in order to preserve the state of one window without affecting states of other windows that may be opened in the application. 
     Other embodiments not described herein are also within the scope of the following claims: