|
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:
- An application on the client machine opens a TCP/IP connection to the
Web server associate with the application running in the Application
Server.
- The Web server (such as, IBM® HTTP Server), is listening on its user
configured port(s) for these connections, and receives the requests.
- IBM HTTP Server forwards (routes) the request to the WebSphere
Application Server plug-in module.
- 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.
- If the plug-in determines that the request is not match an application
running on WebSphere Application Server:
- It rejects the request using an IBM HTTP Server service exit code
- The Web server will invoke any other defined request handlers in an
attempt to find one that will service the request.
- If this process fails, an error 404 is returned to the client
browser.
- 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.
- The plug-in issues a read for this data, and is suspended until all of
the data is available.
- 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. |
|
|