Communicate with Web servers

 

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The WAS 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 WAS. The Web server plug-in uses the XML configuration file to determine whether a request is for the WAS.

 

Overview

The following steps are performed during the plug-in installation process.

  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 WebSphere node agent running on it. Using unmanaged nodes, WAS can represent servers that are not appservers within its configuration topology. This representation enables connection information between those servers and appservers to be maintained.

  2. A Web server definition is created. You can also use either the console or use the script...

    ConfigureWebServerDefintion.jacl

    ...to create a Web server definition.

    If you use the 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.

  3. An application or modules are mapped to a Web server. If an application 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 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, 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 console to change the settings in the plug-in configuration file. When setting up your Web server plug-in, 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

    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 console describes how to add it to the list.

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

      Web server plug-in configuration properties maps each property to one of these topics.

      IBM recommends 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 appserver and then start the appserver again to enable the Web server to locate the plugin-cfg.xml file.

     

  2. 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. 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.

  4. To enable the Application Server to use the private headers that the Web server plug-in sends, make sure the transport you are using is configured for SSL and is trusted. If a trust file definition is not included, the private headers will be ignored, and the appserver might not locate the requested application.

    If you are using an HTTP transport, make sure the transport is configured for SSL and the Trusted custom property for the transport is set to false.

    After you enable the use of private headers, this transport trusts all inbound private headers it receives. Therefore, 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 appserver.)

    • The Web server is a remote IBM HTTP Server V6.0 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.

    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 we 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.

 

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 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 console click...

Servers | Application Servers | server | Administration Services | Web server plug-in configuration service

...and then unselect the option...

Enable automated Web server configuration processing

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.)

Install IBM HTTP Server
Install Web server plug-ins
Edit Web server configuration files
Install Web server plug-in maintenance
Uninstall the Web server plug-ins for WAS
Allow Web servers to access the console
Web server plug-in properties
Web server plug-in configuration service property
Application Server property settings for a Web server plug-in
Web server plug-in configuration properties
Web server plug-in connections
Web server plug-in remote user information processing
Web server plug-ins
Check your IBM HTTP Server version
Create or update a global Web server plug-in configuration file
Gskit install images files
Plug-ins: Resources for learning
Web server plug-in tuning tips
Private headers
plugin-cfg.xml file
Set up a local Web server
Set up a remote Web server
Web server definition
Edit the Web server type
Web server collection

 

Related concepts

Transport chains

 

Related tasks

Configure transport chains
Change the HTTP plug-in configuration
Tune Web servers