Method and system for providing high performance Web browser and server communications

[0002] 1. Field of Use

[0003] The present invention relates to Internet applications and more specifically, to methods and systems for providing efficient communications between Web browser and server systems.

[0004] 2. Description of Related Art

[0005] Significant changes are being made by companies in how they communicate with their customers and the types of services offered due to Web technology. One such change has been the use of a Web browser as a common front end to a mainframe or an enterprise system. In the case of IBM hosts, two basic methods have been utilized to give browsers access to such systems. These methods have been generically called native 3270 and Hypertext Markup Language (HTML) conversion. In the native 3270 method, a special browser is utilized that contains some form of built-in 3270 terminal emulator software and Java applets that know what to do with the 3270 data streams once they reach the desktop system. In the conversion method, 3270 formatted screens are converted into HTML format and posted to a Web server. The converted screens can then be viewed using any browser. These approaches are discussed in greater detail in an article entitled “How To Put Mainframes on the Web” by Salvatore Salamone published in the June 1996 issue of Byte Magazine.

[0006] A disadvantage of the conversion approach is that it may not offer acceptable performance, throughput and response time in a high volume transaction environment. The reason is that the message is translated in a Web server extension and possibly in an intermediate application. Additionally, the message is forced to be routed through several applications and through intermediate applications. To overcome these disadvantages, one system employs an applet that supports mapping screen images associated with a transaction processing application to a modem, intuitive Graphical User Interface (GUI). This eliminates the need for intermediate message translation by having the browser application applet generate and process messages that are understood by the mainframe application. The applet also translates replies received from the application screen image format into a format that can be presented to and understood by the user. This approach is described in the copending patent application entitled “Method for Reducing Message Translation and Traffic Through Intermediate Applications and Systems in an Internet Application”, Ser. No. 08/868,178, filed on Jun. 3, 1997 and assigned to the same assignee as named herein.

[0007] While the above approach improves performance by eliminating the need for intermediate message translation, it is specifically designed to operate with IBM mainframe hosts. Further, since the approach utilizes applets, it requires that the applet and HTML page be downloaded from a server over a non-persistent connection. The applet when executed within the browser is required to open a persistent connection back to the server. Hence, this approach necessitates the establishment of both persistent and non-persistent connections. Further, this approach still is quite time consuming and only performant when the ratio of persistent (applet to server) to non-persistent (HTML page and applet loading) traffic is high. However, even in those cases, the approach still requires that time be expended in establishing additional connections.

[0008] As well known in the art, in the classical client/server model, connections between client and application servers remain open until the client logs off the system. By contrast, in the Web environment, there is no mechanism provided for keeping the client-to-server connection open. Each time a new page is requested, the user, Web server and additional processing must reidentified or reinitialized. The reason is that the Web browser is “stateless”. This “statelessness” makes it difficult to create Web-based applications requiring multiform client-to-server interactions.

[0009] In Web-enabled client/server tools, state and session is usually stored in client-side “cookie” files or hidden fields in HyperText Markup Language (HTML) forms. In Java application server environments, state and session management information is typically stored and managed on the server. Some server products make use of a “context” pool. When transactions are begun, the Web server generates a unique process identifier that is maintained with state information on the server in a “context” pool. Additionally, the process ID (or context ID) is embedded in the HTML passed along to the client, along with other state information. While state information may change during the course of a session, the process ID remains constant until the session terminates and the ID is discarded or returned to the context pool for reuse. These approaches can be viewed as server based approaches.

[0010] Another server based approach provides for retaining mainframe connection information on a web server that locates a user's session when the browser reconnects and delivers the input to the mainframe application being run on the associated mainframe or legacy system. An example of this approach is the GWEB product developed by Gallagher & Robertson described at their website at http://www.gar.no/gweb/.

[0011] The combination of process IDs and storage of state information in a context pool is described in such server based approaches as allowing the execution environment of Java application servers to track the states of numerous clients connected to the Web server. In addition, it allows users to return to Web pages and view them in the state in which they left them. Further, it also ensures that a session is active during the user's entire interaction with the application and keeps track of the state of the client's interaction, as well as any transactions that are in progress, making it possible to commit and roll back operations. For a further discussion of Java application servers, reference may be made to the article entitled “Selecting Java App Servers” by Dan Kara published in the June 1998 issue of Object Magazine.

[0012] The above approaches place the burden on the server system to generate and manage the use of such state information. More importantly, since the use of such state information does not control the establishment of connections, it does not necessarily reduce the traffic on the particular internetwork over which client and server systems communicate.

[0013] To reduce traffic, another prior art system makes an on-line transaction processing system accessible to Web browsers by establishing a predetermined plurality of transaction gateway clients to receive HTTP requests that are received by a Web server from the Web browsers. Concurrent processing of multiple transaction requests from the Web browsers is performed by the plurality of transaction gateway clients. Each transaction gateway client pre-establishes a static connection with the on-line transaction processing system. The pre-established connection allows requests from the Web browsers to be quickly routed to the transaction processing system. The gateway client translates between HTTP formatted requests from the Web browsers and the request format expected by the on-line transaction processing system. This system is described in further detail, in U.S. Pat. No. 5,754,772 that issued on May 19, 1998.

[0014] While the system provides access to a mainframe host, the system has to be able to pre-allocate the required number of static connections and gateway clients beforehand making it more difficult for the system to respond to dynamic changes in operations. Further, the system must expend time in translating requests into the format expected by the on-line transaction processing system.

[0015] Another relevant prior art approach utilizes a server and a web browser terminal emulator for providing a persistent connection to a legacy host system. A computer network environment allows connection of a client system to a legacy host system using such a server system. The server system executes a client thread under a server. The client thread is operable to communicate with the legacy host system across a persistent TCP/IP socket connection. The computer network environment further includes a client system executing an applet process under a web server. The applet process is operable to communicate with the client thread across another persistent TCP/IP socket connection and is operable to provide a terminal session to a user of the client system. This approach is described in U.S. Pat. No. 5,754,830 issued on May 19, 1998. The main disadvantages of this approach pertain to requiring the loading of an applet and the inclusion of a web/emulation server.

[0016] Web browser software is well known in the art for use in retrieving and viewing electronic documents in HTML format from part of the “Internet” known as the “world-wide web”. The World Wide Web part of the Internet is a collection of server computers (i.e., sites) on the Internet, which store HTML documents that can be publicly accessed by computer users connected to the Internet. HTML documents include as a subset, “forms” that allow the user to supply information. Thus, a server system (form provider) can use forms to collect information and to provide back and forth interaction. The use of forms is discussed in the text entitled, “CGI Programming on the World Wide Web,” by Shishir Gundavaram, Copyright©1996, O'Reilly & Associates, Inc.

[0017] As known in the art, HTML documents on the World Wide Web often contain several thousands of bytes and often incorporate several image/graphic files representative of forms, each of which also contain thousands of bytes. At the current transfer speeds used to connect to the Internet, the transmission of such forms can take considerable time (e.g. seconds to minutes) to complete downloading from a computer site.

[0018] In some prior art enterprise systems, so-called “remote forms packages” have been used for terminal based applications to make form processing more time efficient. An example of two such packages are the Transaction Processor Forms Facility (TPFF) product and the Transaction Screen Management System 8 (TSM) product developed and marketed by Bull HN Information Systems Inc. Information about these software products may be found in the Bull publications entitled “Transaction Processing TPFF System Software Release Bulletin, Software Release 8FO1.0, Update 5 GCOS 8”, order number 67 A2 SA65 Rev05, dated March, 1993 and “Tools & Utilities Transaction Screen Management System 8, TSM8 Reference Manual GCOS 8, order number 67 A2 ED42 Rev02, Dated March 1995.

[0019] These packages provide functionality that enables a remote forms mechanism (e.g. TSM8) to create a forms directory for a terminal user as required and also a subdirectory for every unique “connect name” (e.g., TSMTP8). This avoids needless retransmission of forms where form versions are not synchronized among multiple TSM8 installations. Using a co-operative TSM8 local forms storage protocol, the enterprise system connected to the terminal transmits the required forms for a particular user once. The forms received by the terminal are stored on a local storage device for later use. When a terminal user desires access to a form, this causes the generation of a form mount request to the local storage device that results in the display of the requested form on the user's terminal.

[0020] As known in the art, there are systems that provide for the remote retrieval and display management of electronic documents with incorporated images. These systems are able to provide both static and variable data associated with form documents. Examples of systems that provide for the remote retrieval and display management of electronic documents and for using a dialog session context to process electronic forms data are described in U.S. Pat. Nos. 5,778,372 and 5,784,562, respectively. It has been noted that typically, the static portion of such responses are high in data content and the repetitious transmission of this data content for multiple requests can be an inefficient use of bandwidth.

[0021] Thus, the above prior art approaches have not been able to achieve the same levels of network performance in processing HTML based forms as heretofore provided to users accustomed to using terminals with remote forms facilities. An important aspect of the present invention is its recognition of the need for a high performance solution that implements a remote forms capability heretofore provided by enterprise systems that can be utilized with standard browser software.

[0022] Web browser software utilizes a standard application communications protocol such as the HyperText Transport Protocol (HTTP) for processing HTML formatted documents. A number of vendor enterprise systems do not normally process HTML formatted documents and execute HTTP server programs. By contrast, such systems normally execute transactions using their own unique proprietary protocols (e.g. DSA, SNA) specifically designed for their particular applications in contrast to using a standard internet communications protocol such as TCP/IP. Recently, some vendors have implemented the RFC1006 specification that defines a protocol layer that closely resembles the OSI transport layer and runs on TCP/IP. By implementing such a layer, a proprietary protocol like DSA, developed by Bull HN Information Systems Inc., is allowed to run over a TCP/IP network.

[0023] While the above capability is available, there is still need to provide an efficient way of connecting to enterprise systems that operate with different communications protocols.

[0024] Accordingly, it is an object of the present invention to make communications sessions between a Web browser and a server persistent without having to utilize static connections.

[0025] It is a further object of the present invention to provide access to transaction applications running on a server system without having to reformat Web browser pages or alter use of existing protocols.

[0026] It is still a further object of the present invention to provide fast efficient transaction conversations for transferring various kinds of data messages.

[0027] Accordingly, it is another object of the present invention to provide a remote forms facility that operates in conjunction with standard browser software that is easy to manage by a browser user.

[0028] It is a further object of the present invention to provide a remote forms capability characterized by high performance and not having to reformat Web browser pages or alter use of existing protocols.

[0029] It is another object of the present invention to provide a facility for connecting to server systems that utilize different communications protocols.

[0030] The above objects are achieved in a preferred embodiment of the present invention for processing requests generated by a user of a client system for accessing facilities of a server system through a communications network. The client system includes a high performance gateway component that operates in conjunction with a standard browser component. In the preferred embodiment, the gateway component is installed on the same client system or on a client workstation system. The gateway

[0031] Component manages the establishment of persistent sessions in response to client requests and maintains information uniquely identifying existing persistent session connections opened between the client system and the server system.

[0032] In accordance with the present invention, the client side capabilities are enhanced through the inclusion of such a gateway component. The gateway component operatively couples to the standard browser component through a standard browser interface. More specifically, the browser component and gateway component communicate using standard HTTP protocols over a standard browser interface. The gateway component operatively couples to the server system through an internetwork (e.g. Internet). In the preferred embodiment, the gateway component communicates with the server system through several layers of protocols to obviate the need to develop additional protocol software for running existing server applications. The protocols used in the preferred embodiment are HTTP, DSA and TCP/IP.

[0033] According to the teachings of the present invention, the browser component initiates the utilization of new session connections and reuse of existing session connections through an uniquely coded universal resource locator (URL) contained in each issued request. Each URL is passed to the gateway component that examines a context field included within the URL. If the context field has been set to a first value, the gateway component opens a new session connection to the server system and records the session information as an entry in a persistent session table (PST) component maintained by the gateway component. If the context field has been set to a value other than the first value, then the gateway component obtains the session information in the PST component for the established session and passes the data from the browser component to the server system over the existing session connection.

[0034] In the preferred embodiment, the server system's response to an initial request from the gateway component following the establishment of the new persistent connection generates a HTML page with a BASE tag value and also communicates the base value to the gateway component which stores it as part of the PST entry. Relative links in the new HTML page, when activated, are built by the browser incorporating the new BASE value which results in a URL containing the new base value being used on any subsequent requests which uses these links. The BASE value in the URL enables the gateway component to locate the connection, which enables the use of an established persistent connection throughout a session.

[0035] The arrangement of the present invention improves system performance by providing “client side” dynamically controlled persistent connections. This eliminates the need to continuously establish new sessions each time the “stateless” browser component initiates a request. Further, the invention accomplishes this by extending the functionality of the client system by the addition of the gateway component thereby relieving the server system from the burden of having to establish and control persistent connections. Further, the arrangement of the present invention enables the use of persistent connections for transferring data messages other than forms in that the connection information is preserved by the gateway component until the client system has terminated a particular session. Of course, it will be appreciated that when a particular session connection is being utilized by more than one client browser user as described herein, the gateway component retains the connection information until all browser users have completed their respective sessions.

[0036] In accordance with the teachings of the present invention, the gateway component of the preferred embodiment may also include the capability of enabling use of “session pools”. When the gateway component includes this capability, a plurality of persistent sessions connections are initially established. This allows the gateway component to immediately connect a browser component to a server system in response to a browser request having a URL specifying a new session connection. The result is improved performance.

[0037] Also in accordance with the teachings of the present invention, the gateway component may also include the capability of enabling multiplexing persistent session connections for servicing a plurality of browser requests generated during a number of different user sessions. This capability enables several browser users or a single browser user to conduct multiple sessions over a single shared persistent session connection. An advantage of such a capability is an improvement in processing efficiency in handling a high volume of user requests with a limited number of connections.

[0038] In accordance with the teachings of the present invention, the above capabilities are invoked by the browser component by the same basic URL mechanism. The URL of the preferred embodiment may include an optional field portion that enables a user to select either capability or elect not to use a capability in a given situation. For example, a user may elect not to enable the multiplexing capability because of not wanting to share a common persistent connection for reasons of maintaining security.

[0039] In addition to the above, the gateway component of the present invention includes facilities that enable a browser user to communicate with a particular enterprise server system using any one of a number of predefined communications protocols (e.g. DSA, SNA) based on the requirements of the particular system. In accordance with the teachings of the present invention, the basic URL mechanism is used to enable user selection of a particular communications protocol.

[0040] Also in accordance with the teachings of the present invention, the gateway component of the preferred embodiment of the present invention includes a remote forms mechanism that enables storage of the static portion of a message that is local to a Web browser client system so that only variable data needs to be transmitted from a server to the browser client system. As used herein, the term “remote form” refers to the static portion of an HTML page. The mechanism provides local storage in the form of a cache component for retaining the static portions of a plurality of forms in close proximity to the client user. If the remote form is present in the cache component, the gateway component reads the form and merges it with the data returned from the server in its response. The gateway component then forwards the merged data to the browser for display to the user.

[0041] If the remote form is not present in the local cache, the gateway component will make a request to the server for a copy of the form. When the form is received from the server, the gateway component will write it to its cache. The gateway component will then merge the form with the data previously received and forward it to the browser for display to the user.

[0042] The gateway component of the present invention requires no changes to the standard browser system. For example, the gateway component in the preferred embodiment is implemented as a plurality of class objects that can run on the virtual machine included as part of the standard browser and utilize standard Java library routines for establishing and maintaining persistent connections. Hence, the present invention is able to maximize the use of capabilities included with a standard browser.

[0043] Further, the present invention enhances performance by coding all of the pertinent connection information and any available options into the URL. This avoids unnecessary scanning operations for detecting “cookies” in HTTP headers and hidden form fields in HTML document pages. In addition, since the URL does not point to an actual file system directory, it is possible to have a unique URL for every persistent connection. Thus, the gateway component is able to maintain persistent connections while at the same time conforming to the requirements of the HTTP stateless protocol.

[0044] It will be noted that the term “gateway” has been used in referring to the access mechanism of the present invention. In accordance with the teachings of the present invention, the term “gateway” is used in the broad sense to refer to a software component that is installable on a standard personal computer or workstation rather than on a separate or immediate server system, such as a Web or HTTP server system.

[0045] FIG. 1 is an overall block diagram of a transaction processing system that utilizes the method and client browser access component of the present invention.

[0046] FIG. 2 illustrates in greater detail, the client browser system of the present invention.

[0047] FIGS. 3athrough 3cillustrate in greater detail, the components of the client browser system of FIG. 2.

[0048] FIGS. 4aand 4bare flow diagrams used to describe different capabilities of the preferred embodiment of the present invention in managing persistent session connections.

[0049] FIG. 5 is a diagram illustrating the protocol utilized in processing remote forms according to the teachings of the present invention.

[0050] FIG. 1 illustrates a client server system 10 that includes the method and the transaction protocol gateway (TPG) component of the present invention. As shown, the system 10 includes an enterprise server system 20 and a client system 10 that couple to each other through a communications network 14 utilizing the TCP/IP protocol.

[0051] Server System

[0052] The enterprise server system 20 is capable of running transaction processing application software 20-2 and database storage 20-4. The server system 20 can be typically a mainframe transaction processing system, conventional in design, that supports a number of workstation users. For example, the server enterprise system 20 may take the form of the Bull GCOS8 system manufactured by Bull HN Information Systems Inc. that runs transaction processing software designated as TP8. The transaction processing application software stored in enterprise system's memory includes a plurality of transaction program routines (TPRs) designated as 20-2athrough 20-2c.Such routines provide for accessing HTML documents stored on database storage 20-4 and for communicating with the client system 10 using the HTTP protocol. These routines operatively couple to an API library component 20-6. Component 20-6 stores a plurality of runtime routines that enables a TPR transaction program to respond to HTTP requests from browser client system 10. A particular API routine pertinent to the present invention is an HTML_BASE routine that is called by a TPR application program for generating a BASE value as described herein.

[0053] The database storage 20-4 acts as a repository for HTML form based documents. In the preferred version of such software, the HTML documents before being stored are passed through a parser that parses each document into static and dynamic portions. This enables transmission of static HTML records without requiring the server to interpret such records. This arrangement is described in greater detail in the copending application entitled, “Method and Apparatus For Improving Code Execution Performance By Using Parsed HTML,” invented by Michael Giroux, filed on May 13, 1998, bearing Ser. No. 09/078,084 and which is assigned to the same assignee as named herein.

[0054] Client System

[0055] As illustrated in FIG. 1, client system 10 includes a web browser component 10-2, a transaction protocol gateway (TPG) component 10-4, a protocol conversion layer component 10-5 (GTEA) and a forms cache component 10-6. More specifically, with reference to FIG. 1, the client system 10 includes a central processing unit that corresponds to CPU hardware platform 10-3, a main memory 10-1, disk storage 10-10, a plurality of input devices such as a keyboard 10-12 and a pointing device or mouse 10-11 and an output device such as CRT display 10-14, each of which interfaces as indicated. The hardware platform 10-3 runs under the control of an operating system 10-7 such as Windows NT or a UNIX based operating system. The client system 10 also may utilize other software and hardware that includes standard internetwork web browser software. In the preferred embodiment, the web browser component 10-2 includes commercially available application browser software such as Netscape Navigator or Microsoft Explorer that may be Java enabled. That is, browser applets execute under control of a Java virtual machine (JVM) component 10-9. Similarly, the TPG component 10-4 and GTEA component 10-5 also execute under JVM component 10-9. It will also be appreciated that client system 10 also includes appropriate interface network (not shown) that allow the system to send and receive data from any network to which system 10 may connect. For example, the network may be a local area network (LAN) or, more specifically, the Internet. In this regard, it should be noted that in contrast to the prior art applets are not required for establishing persistent connections according to the teachings of the present invention.

[0056] As indicated, the web browser component 10-2 operatively couples to the TPG component 10-4 and communicates with such component through a “non-persistent” connection established by utilizing a standard HTTP protocol (e.g. HTTP 1.0, HTTP 1.1). The TPG component 10-4 includes routines/methods for performing a listener function and a connection function. The listener function involves listening on a configurable port for browser “connections” communicated via HTTP protocol requests (e.g. GET). The connection function involves establishing the required persistent session connections as discussed herein.

[0057] As shown in FIG. 1, the TPG component 10-4 further includes a persistent session table (PST) structure component 10-48 that is used by the connection function for storing session connection information for establishing and maintaining persistent connections between client system 10 and server system 20 in addition to reusing existing session connections. Additionally, the PST component 10-48 is used by routines/methods that manage the sessions taking place such as performing standard “socket” session functions (e.g. open( ), read/write( ), close( )) using standard Java network library routines executing under JVM component 10-9. In the preferred embodiment, PST component 10-48 corresponds to a hash table structure whose entry locations are accessed via a token value. The use of such structures for identifying or tracking objects or entities by a token (e.g. name) as the identifying key is well known in the art. The use of PST component 10-48 is discussed in greater detail herein.

[0058] In greater detail, the GTEA component 10-5 is a “service” which converts DSA calls (i.e., native Bull HN Information Systems GCOS communications protocol) to TCP/IP calls using the so-called RPC1006 protocol. This allows DSA to run over the TCP/IP protocol. In the preferred embodiment, the GTEA component 10-5 establishes a simple API that enables users to write client applications using open TCP/IP standards while at the same time utilizing the advantages of the DSA protocol. The advantages of using such a protocol component are discussed in a presentation entitled, “G&R Host Links BUS 1996”, available at the Gallagher & Robertson web site located at http://www.gar.no/presentations/h196us/. Examples of the GTEA component are provided in the Appendix portion of this specification. In a similar manner, GTEA component 10-5 also enables the SNA protocol layer to run over TCP/IP. As well known, SNA (systems network architecture) is a widely used communications protocol framework developed by IBM Corporation that enables different models of IBM computers to exchange and process data over a communications network. It will be appreciated that when the SOCK protocol is to be used, the GTEA component 10-5 is bypassed. The selection and use of different communications protocols in conjunction with TPG component 10-4 is described in greater detail herein.

[0059] While the preferred embodiment of the present invention is being described relative to a client workstation system, those skilled in the art will appreciate that the present invention is capable of being distributed as a program product in a variety of forms and that the present invention applies equally or operates independently of the type of media used to carry out the distribution. For example, as indicated in FIG. 1, the components of the present invention may be contained on magnetic recordable type media such as a floppy disk 11 of FIG. 1. In this case, the program product components (i.e., TPG component 10-4 and GTEA component 10-5) contained on the disk 11 would be installed on client system 10. More specifically, the contents of disk 11 would be read under the control of hardware platform 10-3 and then loaded onto mass storage 10-10 (e.g. hard disk). As indicated on FIG. 1, these program product components would also be loaded into memory 10-1 for operating in conjunction with the other software components of the client system 10. FIG. 2

[0060] FIG. 2 illustrates in greater detail, the different functional components of TPG component 10-4. As shown, the component 10-4 includes a browser request processing component 10-4 that operatively couples to the PST component 10-48 and to a connection request queue 10-49. Additionally, component 10-4 includes response processing component 10-42 and server forms request processing component 10-46. In the preferred embodiment, the different components of TPG component 10-4 are implemented using Java classes that provide a set of cooperating objects. The architecture defined by such classes and objects is described in greater detail in the Appendix.

[0061] The request processing component 10-40 processes browser connection requests and establishes the required persistent session connections either by establishing new session connections or using existing session connections. Thus, component 10-40 performs the listener and connection functions discussed above. The logic of component 10-40 in processing input connection requests is illustrated in greater detail in FIG. 3a.The operations performed by component 10-40 will be discussed in greater detail relative to that figure.

[0062] The response processing component 10-42 responds to responses received from server system 20 during sessions initiated by browser component 10-2. Accordingly, it communicates with request processing component 10-40 as required for updating the status of existing persistent connections (e.g. close( )). Additionally, since component 10-42 provides responses to the browser component 10-2, the component also is involved in processing remote forms along with component 10-46. The logic of component 10-42 in processing server requests is illustrated in greater detail in FIG. 3b.The operations performed by component 10-42 will be discussed relative to that figure.

[0063] The server forms request processing component 10-46 responds to remote forms requests received from server system 20 via an appropriate remote forms protocol. The component 10-46 passes the results of such form processing to component 10-42 for forwarding to browser component 10-2. The logic of component 10-46 in processing remote form requests is illustrated in greater detail in FIG. 3c.The operations of component 10-46 will be discussed in greater detail relative to that figure.

[0064] FIG. 3a—Gateway Request Processing Logic

[0065] FIG. 3aillustrates the logic of component 10-40. As shown, component 10-40 using its listening function, listens for input connection requests from browser component 10-2 on the configured port (i.e., block 10-40a). For each browser request accepted, component 10-40 examines the request's URL to determine if it contains a session context (SC) value (i.e., block 10-40b). Next, as indicated in block 10-40c,the component 10-40 determines if the SC value equals zero. If the SC value equals zero, this indicates that a session has not been established between the browser component 10-2 and the server system 20 (i.e., “no” path). As indicated in block 10-40c,component 10-40 invokes its connection function to establish a persistent session connection via “sockets”. More specifically, component 10-40 first generates a session context (SC) value and “registers” it in one of the locations of PST component 10-48 (i.e., block 10-40c). That is, as indicated in block 10-40dthe component 10-40 records session information in the assigned PST location and opens a new session connection via a call to protocol conversion layer component 10-5 which uses “sockets” (i.e., issues a socket “open” call).

[0066] The establishing of the session connection involves calling standard socket subroutines and network library subroutines provided by the client system operating system. Once a “session connection” has been established between the server system 20 and client system 10, component 10-40 sends the browser data to server system 20 over the newly established persistent connection (i.e., block 10-40e).

[0067] As indicated, if the session context value contained in the URL is not equal to zero, indicating that a persistent session connection has already been established, component 10-40 checks to see if the session connection is busy (i.e., block 10-40f). It will be noted that TPG component 10-4 allows (serializes) multiple requests from the same browser component over the same session connection. If the session connection specified by the browser request is busy, then component 10-40 queues the entry until the session connection is available (i.e., blocks 10-40fand 10-40g).

[0068] FIG. 3b—Gateway Response Processing Logic

[0069] FIG. 3billustrates the logic of component 10-42. As indicated in block 10-42a,component 10-42 receives responses (messages) from server system 20. If the component 10-42 receives a signal to close the persistent connection from the server system 20 (i.e., block 10-42b), then component 10-42 operates to close the “socket” connection and delete the SC connection entry from PST component 10-48 identified by the SC value. After carrying out those operations, component 10-2 forwards the server response to the browser component 10-2 (i.e., block 10-42d).

[0070] FIG. 3c—Remote Forms Logic

[0071] FIG. 3cillustrates the logic of component 10-46 in processing a request for a remote form from server system 20. As discussed above, the remote form corresponds to the static portion of an HTML page. The TPG component 10-4 provides local storage in forms cache 10-6. This provides additional performance enhancement particularly when used along with the TPG component's capability to maintain persistent connections.

[0072] As indicated in block 10-46aof FIG. 3c,component 10-46 first determines if the HTTP request is to use a cached form. If it is, component 10-46 next determines if the form is cached in forms cache 10-6 (i.e., block 10-46b). This is accomplished by performing a search of the forms cache 10-6 directory. If the form is located, component 10-42 loads or reads out the form from cache 10-6 into a buffer area of memory (i.e., block 10-46c). Next, component 10-46 merges the server data accompanying the server's request obtained from its HTML data storage 20-4 with the static portion of the HTML page (i.e., block 10-46d). The HTML page containing both the form and server data is then sent by component 10-46 to browser component 10-2 for display (i.e., block 10-46e).

[0073] In the case where component 10-46 determines that the form is not cached (i.e., block 10-46b), component 10-46 will make a request for a copy of the form from server system 20. The request is transferred by either opening a new session connection or by using an existing session connection (i.e., block 10-46f). This operation is carried out by invoking component 10-40. As further described herein, component 10-40 sends a request for the specified form using the remote forms protocol illustrated in FIG. 5 (see Appendix for a discussion of this Figure). The determination to open a new session connection or use an existing session connection is made by component 10-40 in the manner described above. As indicated by block 10-46g,upon receipt of a response containing the form (i.e., the static portion of the HTML page), component 10-46 writes the form into the forms cache 10-6 as well as updating its directory to reflect such storage. Next, component 10-46 merges the form with the data previously received from the server system in its HTTP request and forwards the entire HTML page to browser component 10-2 for display (i.e., block 10-46e).

[0074] Description of URL Encoding

[0075] The preferred embodiment of the present invention makes use of the standard Uniform Resource Locator (URL) in establishing persistent session connections. By encoding all required connection information into the URL as described herein in greater detail, the present invention avoids unnecessary scanning of HTTP headers for “Cookies” and hidden form fields as in prior art approaches utilized for maintaining state information. This approach provides optimum performance when used in a high volume enterprise computing environment. Moreover, it allows use of standard browser software and standard HTTP protocols as discussed herein.

[0076] By way of background, the URL is a standard way to specify the location of a resource (e.g. document) anywhere on the World Wide Web. The exact specification of the URL is defined by the specification RFC 1738 that can be located at http://www.w3.org/hypertext/WWW/Addressing/Addressing.html. A URL is composed of three pieces of information:

[0077] 1. Protocol name—typically HTTP

[0078] 2. Server address

[0079] 3. Resource name (e.g a file on a Web server).

[0080] The forms of URLs include absolute and relative. An absolute URL specifies all of the addressing information—protocol, server address, and a resource name that is necessary to locate the desired resource. By contrast, a relative URL (e.g. document) contains only a relative file name. The pathname supplied is relative to the path or directory of the referencing document. Thus, relative URLs allow collections of documents to be moved from one directory to another without affecting the links contained in the documents.

[0081] As well known in the art, browsers combine relative URLs with a document “base” value to form an absolute URL. Every time a browser makes a request for a document, it “remembers” the base name of the document for use in forming absolute URLs for any “HREF” field that specifies a relative name. The HREF field is contained within an HTML anchor element <A> included within the document for specifying a hyperlink (i.e., resource requested when the link is selected by a user). For more information regarding the use of such fields, reference may be made to the Bull HN Information Systems Inc. publication entitled, “Distributed Computing Web 8 User's Guide GCOS 8, order number 67 A2 RJ10 Rev01, Version 3.0, dated July 1998.

[0082] When browser component 10-2 connects to server system 20 using the transaction gateway component 10-4, a persistent connection is established for conducting a DSA session. This enables the browser component 10-2 to reuse the DSA persistent connection for every subsequent message.

[0083] To accomplish this, the gateway component 10-4 retrieves information from the URL of each new message and selects a specific DSA connection based on the part of the URL that contains a session context identifier.

[0084] As discussed above, a URL is composed of a protocol name, server address, and resource name. In the preferred embodiment, the resource name specifies information that is used by the gateway to execute a specific transaction. The general format of a Web URL used by the present invention is as follows:

[0085] http://gateway/node.mailbox.protocol/session context identifier/tp8_command/options

[0086] where:

[0087] The protocol and server address portions of a URL are the same as for a conventional URL that targets any Web server. The format of the rest of the URL is unique to the present invention, as explained herein.

[0088] The resource-name portion of the URL consists of four distinct fields.

[0089] The first field (field 1) specifies the address of the application server. The “protocol” portion specifies the session protocol to be used when establishing a session between the client and the server. Examples of possible protocols and their keywords are:

[0090] SNA Proprietary IBM protocol.

[0091] DSA Proprietary Bull Information Systems protocol based on OSI. This is the default protocol in the preferred implementation. The default protocol can be set using an administrative page provided through a further port connection associated with the gateway component 10-4.

[0092] SOCK Standard UNIX sockets protocol.

[0093] The remainder of this description assumes a URL where the DSA protocol has been selected in which case the URL looks like this:

[0094] Assuming a DSA protocol, the first two elements of field 1 specifies a DSA node name and host mailbox for the desired enterprise server workstation. These values are used by the gateway component 10-4 to establish a connection to the target enterprise server workstation.

[0095] The second field is a context field (field 2) specifies a persistent session connection identifier value, which is guaranteed to be unique. The persistent session context identifier is assigned by the gateway component 10-4 when the browser submits a request that contains a zero in this field. That is, when the session context field is “/0/”, the gateway creates a new DSA connection to the transaction processing (TP) enterprise server workstation that is identified by <node>.<mailbox>. When the connection is established, a unique connection identifier is assigned by the gateway component 10-4 for conducting the session, and all additional requests from the browser specify the persistent session context identifier in place of the original “/0/”.

[0096] The third field (field 3) of the resource name specifies a TP command to be executed.

[0097] The fourth field (field 4) is optional and is passed on to the server without modification by the gateway component 10-4. This field is used to specify options to be used by the TPR transaction program. The TPR transaction program uses a “HTTP_GETPATH” API routine to obtain the value of the options field. Reference may be made to the Appendix in the above-cited Bull Web8 User Manual for descriptions of this API. Note that the TP command name does not appear at the beginning of the input message. To enable the use of default TP command processing, the gateway component 10-4 reorganizes or repackages (i.e., encapsulates) the URL so that it appears to TP to be a native TP command. This obviates the need to change the TP executive software. The gateway component 10-4 copies the TP command name to the beginning of the input message. For example, consider the following URL.

[0098] http://gateway/sys1.tp8ws/0/logon/12345

[0099] When processing this URL, the browser component 10-2 makes a connection to the gateway component 10-4 at IP address “gateway” and uses the “http” protocol to submit a “GET” request. The HTTP request message sent by the browser component 10-2 to the gateway component 10-4 is:

[0100] GET /sys1.tp8ws/0/logon/12345 HTTP/1.0

[0101] The gateway component 10-4 examines this message and copies the TP command name to the beginning of the message. The message submitted to the TP server workstation is:

[0102] logon context=<cid>.<tod><CRLF>

[0103] <CRLF>

[0104] GET /sys1.tp8ws/0/logon/12345 HTTP/1.0

[0105] In this example, the gateway component 10-4 copied the “logon” command name to the beginning of the message. In addition, the gateway component 10-4 detected a session identifier of “/0/” and established a new persistent connection for conducting a browser session. Because the gateway component 10-4 created a new persistent connection, the new connection identifier is also passed to the TPR transaction program as part of the message prefix.

[0106] The information added by the gateway component 10-4 must conform to the HTTP protocol specification to avoid any ambiguity during the processing of each input message. Consequently the line added by the gateway is terminated by a CRLF sequence. The CRLF (carriage return/line feed) is the standard HTTP protocol line terminator. This sequence is also referred to as a new line and typically appears in the document as <NL>. A line that consists of only the CRLF sequence is added to mark the end of the information in the gateway header. The original HTTP request submitted by the browser component 10-4 follows the “gateway” header. The description of the runtime library (i.e., API library 20-6) refers to this gateway header as an “environment.” The HTTP_GETENV family of routines (which are described in the Appendix of the previously referenced Bull User Manual) are used to process the gateway header.

[0107] For the browser component 10-2 to submit requests using the newly created DSA session connection, the browser component 10-2 must determine that the base URL contains the newly assigned session context identifier. Continuing with the previous example, it is assumed that the gateway component 10-4 created a new connection and assigned a session context identifier of “1234.abcd”. The message sent by the browser component 10-2 to the server system 20 then is:

[0108] logon context=1234.abcd<CRLF>

[0109] <CRLF>

[0110] GET /sys1.tp8ws/0/logon/12345 HTTP/1.0

[0111] Usually, if the page returned by the LOGON command contains a relative URL, the browser component 10-2 forms a new absolute URL using the current document base, which in this example is:

[0112] http://gateway/sys1.tp8ws/0/.

[0113] However, using this document base results in yet another DSA session connection being created, and the new message is sent to the new session connection. To send messages to the DSA session connection that was created for the LOGON request, the browser component 10-2 must establish that the document base is actually:

[0114] http://gateway/sys1.tp8ws/1234.abcd/.

[0115] The HTML specification provides a convenient mechanism for this purpose; the <BASE> tag. The HTML <BASE> tag provides a standard method for an application to explicitly specify the base for the document that contains the <BASE> tag. Using the <BASE> tag, the TP transaction application program can use the HREF attribute to specify any arbitrary document base. In our example, the application would generate the following sequence of HTML in response to the original LOGON request:

[0116] <HTML>

[0117] <HEAD>

[0118] <BASE HREF=“http://gateway/sys1.tp8ws/1234.abcd/”>

[0119] </HEAD>.

[0120] When the browser component 10-2 receives a document that contains the <BASE> HTML element, the browser component 10-2 uses the information provided in the HREF attribute to resolve any relative references that are contained within the HTML document.

[0121] Because most TP Web applications need to generate <BASE> tags, the API library 20-6 of the enterprise server software includes the HTML_BASE routine illustrated in the Appendix, which can be used to generate the complete <BASE> element. The routine returns the result to the TPR transaction program, which can then include the generated <BASE> in Web pages.

[0122] The gateway component 10-4 requires the TPR transaction program to define an additional application-specific suffix for the session context identifier. The session context identifier generated by the gateway component 10-4 contains two values and the complete session context identifier includes a third value that contains an application-specific value.

[0123] A TPR transaction application program must specify an application-context value whenever the <BASE> is generated. This context value must be non-zero, and has a maximum size of 32 bits.

[0124] In addition, an application can specify a new application-specific value at any time to provide additional control over the application. Changing this portion of the session context identifier prevents the user from submitting requests from bookmarks, thus providing an additional form of protection against misuse.

[0125] Whenever a TPR transaction program assigns a new application-context value, the new base information must be provided to the browser component 10-2 via the <BASE> element. In addition, the gateway component 10-4 must be notified of the new application context. Communication between the TPR transaction program and the gateway component 10-4 takes place on the HTTP status-response line using the message portion of the status record. If the TPR transaction program wants to set the application-context value to “5678”, then the complete session context identifier in the example is:

[0126] 1234.abcd.5678.

[0127] The TPR transaction program is responsible for generating the complete HTTP response header and the HTML document. The HTTP response begins with an HTTP status, which includes a numeric completion-status code and a text message. In non-Web environments, the text portion typically is ignored and is provided only as a convenience for debugging the HTTP protocol. In the preferred embodiment, this field is used to communicate from the TPR transaction program to the gateway component 10-4.

[0128] The message sent to the browser component 10-2 includes an HTTP response header that identifies the new application-context value, and an HTML <BASE> element that identifies the complete session context identifier.

[0129] HTTP/1.0 200 CONTEXT=5678<NL>

[0130] Content-type: text/html<NL>

[0131] <NL>

[0132] <HTML>

[0133] <HEAD>

[0134] <BASE HRBF=“http://gateway/sys1.tp8ws/1234.abcd.5678/”>

[0135] </HEAD>

[0136] <BODY>

[0137] Rest of HTML response goes here

[0138] </BODY>

[0139] </HTML>

[0140] The above example shows an HTTP response header that conforms to the HTTP version 1.0 specification. The completion code of “200” (i.e. described in the HTTP1.0 and HTTP1.1 specifications) indicates that the request was processed successfully. The text that follows the completion code contains the reserved word “CONTEXT=” and the new application-context value of “5678,”. The gateway component 10-4 copies this value to the PST entry allocated to the current DSA session connection.

[0141] Any subsequent input message that specifies the gateway context identifier is validated by the gateway component 10-4 to include the correct time-of-day and application-context value. Failure to match on either field results in an HTTP response indicating that the requested resource was not found.

[0142] In addition, the <BASE> header element contains the complete session context identifier, including the application-context value. The browser component 10-2 uses this new base information when constructing absolute URLs for the links that are included in the current document.

[0143] The overall operation of the preferred embodiment of the present invention will now be described with respect to FIGS. 1 through 5. The flow chart of FIG. 4aillustrates the overall operation in establishing and using persistent connections according to the teachings of the present invention. These operations are diagrammatically depicted in FIG. 4b.Referring to FIG. 4a,it is seen that it is assumed that the user at the client system 10 enters an HTTP request containing a URL with a context field via the browser component 10-2 (item 1 in FIG. 4b). More specifically, the user enters a URL containing the usual fields plus a context key field containing a value of zero (e.g. via keyboard 10-12 of FIG. 1. By way of example, the user enters the following URL:

[0144] HTTP://sandpiper: 8080/ph45.web8.dsa/0/logon where:

[0145] sandpiper:8080 address of the TPG component 10-4;

[0146] ph45.web8.protocol address of the server system 20 (protocol is the protocol to be used between the TPG component 10-4 and the server system 20 (e.g. DSA, SNA or SOCK);

[0147] 0 value of the context key;

[0148] logon target transaction/application.

[0149] The browser component 10-2 sends the request via the HTTP protocol to the TPG component 10-4 in a conventional manner (i.e., block 400 of FIG. 4a). The TPG component 10-4 listening on the configured port (e.g. 8080) receives the input connection request and examines the URL's context field value (i.e., block 402). The specific coding of this value enables the component 10-4 determine if browser component 10-2 has requested that a new session connection be opened or has requested that an existing session connection is to be used for forwarding the request to server system 20. As indicated in block 404, TPG component 10-4 examines the context field value and in this case, sees that it has a value of zero. This indicates that no context for this session exists (i.e., no session connection has been established).

[0150] As indicated in block 406 of FIG. 4a,TPG component 10-4 opens a new persistent session connection to server system 20 using the protocol specified in the server address field of the URL (i.e., DSA in this example). This is done by invoking a connection function within the browser request processing component 10-40 of FIG. 2. In the simplest case, the HTTP protocol (i.e., SOCK) could also be specified where the host system (i.e.,server system 20) includes the capability of utilizing this protocol.

[0151] The TPG component 10-4 also records the pertinent session information as an entry in the PST table 10-48 as follows:

[0152] Next, the TPG component 10-4 generates a unique context key value. The context key value consists of the following three parts: (X) Time of day in milliseconds as required for uniquely identifying the PST session entry; (Y) Token to access the session entry in the PST table 10-48 and (Z) Optional server application specific value which can be used to invalidate an HTML link.

[0153] As previously discussed, the server application value (Z) can be used by an application to invalidate links on ”back” browser pages and to prevent requests being made from “bookmarked” pages. The value of Z is updated in the PST table 10-48 by TPG component 10-4 each time a response is sent from the server system 20 to the client system 10. If a new BASE is generated by the TPR application with the new Z value, the browser component 10-2 will build a page using the new BASE. This means that relative links on the new page will be built using the new context and, more specifically, the new Z value. Subsequent requests from the browser component 10-2 with a Z value other than the current Z value in the PST table 10-48 (that is, build with an out-of-date context) will be rejected. Thus, only links with the latest context are considered valid.

[0154] Also, as indicated in block 406, TPG component 10-4 generates a pseudo HTTP header having the format:

[0155] logon context=x.y.z

[0156] <nl>

[0157] where logon in the present example is the target application obtained from the URL and specifies the transaction routine (i.e. logon TPR 20-2a) to be run on server system 20. Next, TPG component 10-4 forwards the HTTP header and body from the browser component 10-2 to server system 20 as indicated in block 406 (i.e., item 2 in FIG. 4b). The browser request processing component 10-40 forwards the request using the persistent session connection in the process of being established on the client system 10 by the TPG component 10-2. To complete the persistent session connection, as discussed herein, the server system 20 cooperates by furnishing a base tag value that enables complete identification of the session connection by both systems.

[0158] As indicated in block 408, upon receipt of the transaction name (i.e., logon), server system 20 invokes the logon transaction processing routine (TPR) 20-2a(i.e., item 3 in FIG. 4b). The TPR 20-2aduring its normal processing constructs an HTML response. Part of this response includes an HTML BASE tag that incorporates the context key. The TRP 20-2adoes this by calling the BASE routine contained in API library 20-6. The server system 20 sends the response to TPG component 10-4 over the established persistent session connection (item 4 in FIG. 4b).

[0159] As indicated in block 410, the response processing component 10-42 of TPG component 10-4 forwards the server system response to browser component 10-2 via the HTTP protocol over a non-persistent connection established via “sockets” (item 5 in FIG. 4b). The component 10-42 forwards the BASE tag to component 10-40. As indicated in block 412, using the BASE tag, browser component 10-2 resets the base URL in a standard manner. The result of this operation is that any link that the user selects will cause the browser component 10-2 to form an address based on the reset URL base and the link information. Thus, link addresses will have URLs that contain the context key.

[0160] When the user selects a link address via mouse 10-11 and submits a subsequent request, browser component 10-2 passes an non-zero context key value to the TPG component 10-4 (item 6 in FIG. 4b). As a result, as indicated in block 414, TPG component 10-4 uses the non-zero context value (i.e., x.y.z) to locate the session information pertaining to the persistent connection in the PST component 10-48. The TPG component 10-4 passes the data received from browser component 10-2 to server system 20 over the persistent session connection located by the context key value (item 6 in FIG. 4b).

[0161] As indicated in FIG. 4a,this cycle of operation is repeated during the execution of a transaction processing application program (e.g. TPR 20-2b). Upon completing the processing of all required transactions, the browser user can then generate a request signaling termination of the session. More specifically, the browser user generates a request to execute a “logoff” TPR (i.e., a request to be disconnected from server system 20).

[0162] In greater detail, the browser user enters the following URL:

[0163] HTTP://sandpiper:8080/ph45.web8.dsa/x.v.z/logoff

[0164] where the target transaction/application specified is TPR 20-2c.This causes TPG component 10-4 to forward to server system 20, the browser initiated HTTP GET request having the format:

[0165] GET/ph45.web8/x.y.z/logoff HTTP/1.0.

[0166] This results in server system 20 invoking logoff TPR 20-2c.TPR 20-2cprovides the appropriate response to browser component 10-2 by including a CONTEXT=0 in the response status line, i.e., HTTP/1.0 200 CONTEXT=0. This is the signal from the host system to TPG component 10-4 to close the session.

[0167] The TPG component 10-4 passes the server system's response to browser component 10-2. In addition, TPG component 10-4 closes the browser socket connection used for communicating with browser component 10-2. Also, when such session closing takes place, TPG component 10-4 removes the session entry information form PST table component 10-48.

[0168] Also, the session may be closed by TPG component 10-4 because of browser user inactivity or by server system 20 via sending a close response. In the case of inactivity, if no traffic is seen on a session over a specified time interval, the session is considered to be inactive. In the preferred embodiment, a default time-out interval of 10 minutes is established by TPG component 10-4 but this value can be varied administratively. For example, the value can be established by accessing an administrative page via a predefined port (e.g. port 8081) associated with TPG component 10-4.

[0169] The described technique of using a context key value allows TPG component 10-4 to map a non-persistent session between browser component 10-2 and TPG component 10-4 to a persistent session connection between TPG component 10-4 and server system 20.

[0170] Additional Persistent Session Related Options

[0171] As indicated above, the TPG component 10-4 of the preferred embodiment may include additional options that can be selected by browser users for use in different operating environments. More specifically, an option word in the URL is used to control additional options. These options include session multiplexing and session pooling.

[0172] The format of the URL with the option field is as follows:

[0173] <TPG address>/<server add1>.<server add2>.<protocol>.<options>/context/command

[0174] where options are:

[0175] p=pool and m=multiplex.

[0176] The “p” option flag designates when a browser user has enabled the use of a session connection from a “session pool”.

[0177] During TPG component 10-4 startup, a predetermined number of session connections per server is established. The TPG component 10-4 tracks the session connections in a session pool table that indexes entries in the PST table 10-48. As browser component 10-2 requests are serviced, URLs with contexts which indicate new session connections (context=0) are allocated session connections by TPG component 10-4 from the session pool if the “p” option is set. When the server system 20 indicates that the session connection is to be closed, TPG component 10-4 returns the session connection to the session pool.

[0178] The session pool can be administratively expanded or contracted according to usage within preset minimum and maximum limits.

[0179] The “m” option designates when a browser user has enabled use of a session that can be multiplexed over persistent session connections. When a request is received with the “m” option set, TPG component 10-4 attempts to locate a connection for the same server system (e.g. within PST table 10-48) which is not busy and for which the “m” flag is set or the connection is not is use. When using this option, additional software is required to be installed on the server system to demultiplex sessions and to route messages appropriately.

[0180] From the above, it is seen how the TPG component of the preferred embodiment according to the teachings of the present invention manages persistent session connections in response to browser user requests in a manner that provides high performance. Also, the TPG component provides further performance improvements, such as handling remote forms, managing and providing session connection pool and multiplex options and providing a variety of different communications protocols. By utilizing URLs in conjunction with such different capabilities, a client system browser user has the ability to adapt the client system to accommodate traffic demands and different operating environments. For example, a browser user may select a number of different communications protocols in handling different requests involving different host/server systems. In response to such selections, the TPG component would generate a corresponding number of different session objects (e.g. DSA session, SNA session objects) for carrying out such communications in accordance with the teachings of the present invention.

[0181] The foregoing discussion of the present invention has been presented for the purposes of illustration and description. Further descriptions are also provided in the Appendix. Such descriptions are not intended to limit the teachings of the present invention to the forms and implementations disclosed herein. Consequently, many variations and modifications commensurate with the above teachings, within the skill and knowledge of the relevant art, are within the scope of the present invention. For example, the teachings of the present invention should not be limited to the types of protocols disclosed, the type of client system and server systems described or to the specific type of software disclosed herein.

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[0182] While in accordance with the provisions and statutes there has been illustrated and described the best form of the invention, certain changes may be made without departing from the spirit of the invention as set forth in the appended claims and that in some cases, certain features of the invention may be used to advantage without a corresponding use of other features.