Communicating with Web servers

The WebSphere Application Server works with a Web server to route requests for dynamic content, such as servlets, from Web applications. The Web servers are necessary for directing traffic from browsers to the applications that run in WebSphere Application Server. The Web server plug-in uses the XML configuration file to determine whether a request is for the WebSphere Application Server.

Before you begin

About this task

The following steps are performed during the plug-in installation process. See the Plug-in Installation Roadmap for additional information.
  1. A Web server definition is created.
    You can also use either the administrative console or use the ConfigureWebServerDefintion.jacl script to create a Web server definition. If you use the administrative console:
    1. Select the node that was created in the preceding step, and in the Server name field, enter the local name of the Web server for which you are creating a Web server definition.
    2. Use the wizard to complete the Web server definition.
  2. An application or modules are mapped to a Web server. If an application that you want to use with this Web server is already installed, the application is automatically mapped to the Web server. If the application is not installed, select this Web server during the Map modules to servers step of the application installation process.
  3. The master repository is updated and saved.

When you install a plug-in, the configuration file for that plug-in is automatically created. You can change or fine tune the default settings for the properties in this configuration file. If change any of the settings, you must regenerate the file before your changes take affect.

Generating or regenerating the configuration file might take a while to complete. After it finishes, all objects in the administrative cell use their newest settings, which the Web server can access. If the Application Server is on the same physical machine as the Web server, the regeneration usually takes about 30 to 60 seconds to complete. The regeneration takes longer if they are not both on the same machine.

The following procedure describes the steps for updating the plug-in configuration file, including configuring for SSL and Web server tuning

Procedure

  1. Use the administrative console to change the settings in the plug-in configuration file.
    When setting up your Web server plug-in, you must decide whether or not to have the configuration automatically generated in response to a configuration change. When the Web server plug-in configuration service is enabled and any of the following conditions occur, the plug-in configuration file is automatically generated:
    • When the Web server is created or saved.
    • When an application is installed.
    • When an application is uninstalled.
    • When the virtual host definition is updated
    Important: When the plug-in configuration file is first generated, it does not include admin_host on the list of virtual hosts. Allowing Web servers to access the administrative console describes how to add it to the list.
    You can either use the administrative console, or issue the GenPluginCfg command to regenerate your plugin-cfg.xml file.
    Avoid trouble: You must delete the plugin-cfg.xml file in the profile_root/config/cells directory before you complete this task. Otherwise, configuration changes do not persist to the plugin-cfg.xml file.gotcha

    To use the administrative console:

    1. Select Servers > Web Servers > webserver > plug-in properties.
    2. Select Automatically generate plug-in configuration file or click one or more of the following topics to manually configure the plugin-cfg.xml file:
      • Caching
      • Request and response
      • Request routing
      • Custom Properties
      Web server plug-in configuration properties maps each property to one of these topics.
      Note: It is recommended that you do not manually update the plugin-cfg.xml file. Any manual updates you make for a given Web server are overridden whenever the plugin-cfg.xml file for that Web server is regenerated.
    3. Click OK.
    4. You might need to stop the application server and then start the application server again to enable the Web server to locate the plugin-cfg.xml file.
  2. [Version 6.0.1 and later] Optional: Edit the plug-in configuration file. You should not have to edit the configuration file. If you do edit this file remember that:
    • The file is in ASCII format (ISO-98859-1).
    • Any manual changes you make to the file are overwritten the next time the file is regenerated.
  3. If you want to use Secure-socket layer (SSL) with this configuration, use the plug-in's installation wizard to install the appropriate GSKIT installation image file on your workstation.

    See Configuring the Web server plug-in for Secure Sockets Layer for information on how to configure GSKIT.

  4. If you want to enable the Application Server to use the private headers that the Web server plug-in sends, set the TrustedProxy HTTP transport custom property to true.

    After you enable the TrustedProxy custom property, this transport trusts all inbound private headers it receives. Therefore, you must ensure that all inbound paths to this transport are trusted.

  5. Tune your Web server. See Tuning Web servers for more information.
  6. Propagate the plug-in configuration. The plug-in configuration file (plugin-cfg.xml) is automatically propagated to the Web server if the Web server plug-in configuration service is enabled, and one of the following is true:
    • The Web server is a local Web server. (It are located on the same machine as an application server.)
    • The Web server is a remote IBM HTTP Server Version 6.0 that has a running IBM HTTP Server administration server.

    If neither of these conditions is true, the plugin-cfg.xml file must be manually copied to the remote Web server's installation location. Copy plugin-cfg.xml in <WASROOT>/profiles/<profilename>/config/cells/../../nodes/../servers/<webservername> to the Web server host location, which is <PluginInstallRoot>/config/<webservername>/.

    Important: If you use the FTP function to perform the copy, and the configuration reload fails, check the file permissions on the plugin-cfg.xml file and make sure they are set to rw-r--r--. If the file permissions are not correct, the Web server is not able to access the new version of the file, which causes the configuration reload to fail.
    If the file permissions are incorrect, issue the following command to change the file permissions to the appropriate settings:
    chmod 644 plugin-cfg.xml

    [AIX] The AIX FTP function does not preserve file attributes. Therefore, if you need to manually copy the plugin-cfg.xml from an AIX operating system, you might want to use the AIX RCP function instead of the FTP function to copy the file.

Results

The configuration is complete. To activate the configuration, stop and restart the Web server. If you encounter problems restarting your Web server, check the http_plugin.log file for information on what portion of the plugin-cfg.xml file contains an error. The log file states the line number on which the error occurred along with other details that might help you diagnose why the Web server did not start. You can then use the administrative console to update the plugin-cfg.xml file.

If applications are infrequently installed or uninstalled, which is usually the situation in a production environment, or if you can tolerate the performance impact of generating and distributing the plug-in configuration file each time any of the previously listed actions occur, you should consider enabling this service.

If you are making a series of simultaneous changes, like installing numerous applications, you might want the configuration service disabled until after you make the last change. The Web server plug-in configuration service is enabled by default. To disable this service, in the administrative console click elect Servers > Application Servers > server_name > Administration Services >Web server plug-in configuration service and then unselect the Enable automated Web server configuration processing option.

Tip: If your installation uses a firewall, make sure you configure the Web server plug-in to use a port that has been opened. (See your security administrator for information on how to obtain an open port.)



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Last updated: Aug 29, 2010 6:22:59 PM CDT
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