Configure Web server plug-ins

An application server works with a Web server to handle requests for Web applications. The Web server and application server communicate through a WebSphere HTTP plug-in for the Web server.

If you specify a Web server when you install WebSphere Application Server - Express, the installation program modifies the Web server configuration file to establish a plug-in for the specified Web server. Plug-ins provide some advantages over other communication methods:

XML-based configuration file
Standard protocol recognized by firewall products
Security using HTTPS, replacing proprietary OSE over SSL

Note: You are not required to use a Web server plug-in and Web server to serve requests to the application server. You can use the internal HTTP transport instead of the Web server plug-in and Web server. However, external Web servers, such as IBM HTTP Server (powered by Apache), provide additional functions that might be useful in your application server environment. If you choose to use the internal HTTP transport to directly serve requests, consider configuring error logging and access logging for the internal HTTP transport. For information about administering HTTP transports, including configuring error logging and access logging, see Administer internal HTTP transports.

To configure the plug-in for your Web server, follow these steps:

Verify that the Web server is configured to perform operations that your Web applications require, such as GET and POST. If an operation is not enabled when a servlet or JSP file requiring the operation is accessed, an error message is displayed, such as this one from IBM HTTP Server:
```
HTTP method POST is not supported by this URL.
```
For information about administering your Web server, refer to the Web server's documentation.
If you experience problems starting your Web server, check the http_plugin.log file for information about which section of the plug-in configuration file contained the error. The log file is located in the /QIBM/UserData/WebASE51/ASE/instance/logs directory, where instance is the name of your application server instance. The log file provides the line number on which the error occurred along with other details that might help you diagnose why the Web server is not starting. A frequent reason for a Web server not starting is an improper entry in a plug-in configuration file.
Make the necessary changes to the configuration file. For more information, see Manually edit the plug-in configuration.
After you make changes to the configurations for plug-ins, transports, or virtual hosts, you must regenerate the configuration file so that the changes take effect. For more information, see Regenerate the Web server plug-in configuration.

These topics provide information about the plugin-cfg.xml file and a sample of the file:

The plugin-cfg.xml file
This topic describes the elements and attributes in the plugin-cfg.xml configuration file.

Sample plugin-cfg.xml file
This topic provides a sample plugin-cfg.xml file.

Manually edit the plug-in configuration
In some cases, you might need to manually update the plugin-cfg.xml file. This topic describes how to edit the file.

Web server plug-in connections
This topic describes how the WebSphere Web server plug-in establishes and maintains persistent connections to an application server's HTTP and HTTPS transports.

Web server plug-in remote user information processing
This topic describes how the Web server plug-in handles calls to the getRemoteUser() method to provide information to an application.