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.

About this task

The appropriate plug-in file is installed. In addition, an http profile is created (/QIBM/UserData/WebSphere/Plugins/V85/webserver/profiles/http). The http profile can be used to facilitate the creation of web server definitions. See the topic about selecting a web server topology diagram and road map for instructions on how to configure IBM HTTP Server for IBM i to communicate with an application server.

The following steps are performed during the plug-in installation process. See the Plug-in Installation Roadmap for additional information.

1. A node is created.

   An unmanaged node is created when the web server is on a different computer from the application server. An unmanaged node is a node that does not have a node agent running on it. Using unmanaged nodes, the product can represent servers that are not application servers within its configuration topology. This representation enables connection information between those servers and application servers to be maintained. See the topic about adding, managing, and removing nodes for more information.

2. 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.

3. 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.
4. The master repository is updated and saved.

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.

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.

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

   Avoid trouble: When the plug-in configuration file is first generated, it does not include admin_host on the list of virtual hosts. The information about 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.

   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. Propagate the plug-in configuration.
      To propagate the plug-in configuration from the administrative console, click Servers > Server Types > Web serversweb_server_namePropagate plug-in.

      Another method to propagate the plug-in configuration is to run the GenPluginCfg command. For more information, see the GenPluginCfg command documentation.

      You do not need to propagate the plug-in configuration if the web server is on the same machine as the associated stand-alone version of the product. If the propagation of the plug-in configuration fails due to an unknown cause, you must manually copy the plugin-cfg.xml file to the location for the remote web server installation.

      Avoid trouble: If you use the FTP function to perform the copy, and the configuration reload fails, check the file authorities on the plugin-cfg.xml file and make sure that users QTMHHTTP, QNOTES and QEJBSVR have RWX authority. If the authorities are not correct, the web server cannot access the new version of the file, which causes the configuration reload to fail. To check the authorities, run the following IBM i command:

      wrklnk 'plug_in_folder_location/plugin-cfg.xml' 

      Then select option 9 to view the authorities that are assigned to the users (QTMHHTTP, QNOTES, and QEJBSVR).

      If the authorities are incorrect, issue the following IBM i command to change the file authorities to the appropriate settings:

      CHGAUT USER(QEJBSVR QTMHHTTP QNOTES) OBJ('plug_in_folder_location/plugin-cfg.xml') DTAAUT(*RWX)

      The plug_in_folder_location is the location you specified when you transferred the plugin-cfg.xml file.
   5. 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. Tune your web server.
   See the page about tuning web servers for more information.
3. 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 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.

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

4. 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.