Protocol used by clients establishing connections to WebSphere Application Server applications
 Technote (FAQ)
 
Problem
Occasionally, an error is encountered while attempting to interact with an application on WebSphere® Application Server. What is the appropriate sequence of events for connecting from a client to a server application?
 
Cause
Difficulty connecting a client to applications deployed on WebSphere Application Server
 
Solution
Here are the sequence of events used by a client application (such as, a browser), when it attempts to connect to a server application on WebSphere Application Server:
  1. An application on the client machine opens a TCP/IP connection to the Web server associate with the application running in the Application Server.
  2. The Web server (such as, IBM® HTTP Server), is listening on its user configured port(s) for these connections, and receives the requests.
  3. IBM HTTP Server forwards (routes) the request to the WebSphere Application Server plug-in module.
  4. The WebSphere Application Server plug-in module uses the configuration information in the plugin-cfg.xml file to determine that the request should be processed by the Application Server.
  5. If the plug-in determines that the request is not match an application running on WebSphere Application Server:
    1. It rejects the request using an IBM HTTP Server service exit code
    2. The Web server will invoke any other defined request handlers in an attempt to find one that will service the request.
    3. If this process fails, an error 404 is returned to the client browser.
  6. For WebSphere Application Server requests, the plug-in uses the information available as part of the TCP/IP communication protocol, to determine the amount of data sent by the client application.

    Note: In order for the receiving application to determine if the message has been received correctly, the message header contains number of bytes transmitted.
  7. The plug-in issues a read for this data, and is suspended until all of the data is available.
  8. Once the complete request has been received, the plug-in establishes a similar connection to the application on the Application Server, and forwards the request.

When an error occurs in this process, it is essential to determine at what point the failure actually occurred. If the failure occurred in the network between the client machine, and the Web server/plug-in, then the plug-in will time-out attempting to read the request.
 
Related information
MustGather: Readme First
 
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > IBM HTTP Server
Operating system(s): Windows
Software version: 6.0
Software edition:
Reference #: 1066876
IBM Group: Software Group
Modified date: Sep 16, 2004