Implementing a web server plug-in

This topic describes how to implement a web server plug-in. The product 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 on an application server. The web server plug-in uses the XML configuration file to determine whether a request is for an application server.

Before you begin

  • See the information about choosing a front end for your WebSphere® Application Server topology. This topic helps you determine whether to set up a web server plug-in, a proxy server, or a secure proxy server to provide session affinity, failover support, and workload balancing for your WebSphere Application Server topology. Install your web server if it is not already installed.
  • [z/OS]Make sure the appropriate plug-in file has been installed on your web server and the configureweb_server_name script has been run to create and configure the web server definition for this web server.

    [z/OS]If you are using the IBM® HTTP Server for z/OS®, powered by Apache, which is provided with the product, see the information about installing and configuring the plug-in for IBM HTTP Server for WebSphere Application Server on z/OS.

    [z/OS]If you are using the IBM HTTP Server Version 5.3, which is provided with the z/OS base operating system, see the information about installing and configuring the web server plug-in for IBM HTTP Server for z/OS V5.3.

    [z/OS]If you are using a distributed platform web server with a version of the product that is running on z/OS operating systems, use an FTP connection to send the plug-in to the web server and use the Plug-in Installation Wizard to install the appropriate plug-in file to your web server.

If you are making a series of simultaneous changes, such as 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 Servers > Server Types > WebSphere application servers > server_name > Administration services > Web server plug-in configuration service, and then clear the Enable automated web server configuration processing option.

Avoid trouble: If your installation uses a firewall, make sure that you configure the web server plug-in to use a port that has been opened. See your security administrator for information about how to obtain an open port.

About this task

[z/OS]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 ConfigurewebServerDefinition.jacl script to create a 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.

[z/OS]When you configure a plug-in, the configuration file for that plug-in is automatically created. You can change or tune the default settings for the properties in this configuration file. If you change any of the settings, you must regenerate the file before your changes take effect.

[z/OS]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 workstation as the web server, the regeneration usually takes about 30 to 60 seconds to complete. The regeneration takes longer if the application server and web server are on different workstations.

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 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

    You can either use the administrative console, or issue the GenPluginCfg command to regenerate your plugin-cfg.xml file.

    Complete the following steps to regenerate your plugin-cfg.xml file by using the administrative console:

    1. Select Servers > Server Types > web Servers > web_server_name > 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:
      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.
      • Caching
      • Request and response
      • Request routing
      • Custom Properties
      See the topic about web server plug-in configuration properties for information about how to map each property to one of these topics.
      Avoid trouble: Do not manually update the plugin-cfg.xml file. Any manual updates you make for a web server are overridden whenever the plugin-cfg.xml file for that web server is regenerated.
    3. Click OK.
    4. You might have to stop the application server and then start the application server for the web server to locate the plugin-cfg.xml file.
  2. [z/OS]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 conditions is true:
    • The web server is a local web server, which means that the web server is located on the same workstation as an application server.
    • The web server is a remote IBM HTTP Server Version 7 that has a running IBM HTTP Server administration server.

    If neither of these conditions are true, you must manually copy the plugin-cfg.xml file to the location of the remote web server installation. Copy the plugin-cfg.xml file in <app_server_root>/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 copy the file, and the configuration reload fails, check the file permissions on the plugin-cfg.xml file, and make sure that 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

    The remote web server installation location is the location you specified when you created the node for this web server.

  3. Copy the keystore file to the keystore directory on your web server.
    Avoid trouble: This step is required for the web server to function properly.

    For detailed instructions on copying the keystore file, read the topic on configuring the web server plug-in for Secure Sockets Layer.

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 about 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, consider enabling the configuration service.