Communicating with Web servers

Communicating with Web servers

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Overview

WebSphere Application Server (WAS) works with Web servers to route requests for dynamic content, such as servlets, from Web applications. The Web server plug-in uses an XML configuration file to determine whether a request is from the Web server or the Application Server.
WebSphere Appplication Server Network Deployment (C5886ML) is bundled with a Web Server Plug-in Installation Wizard. Note that not all distros of WAS or WAS Network Deployment are bundled with the wizard.
The following steps are performed during the plug-in installation process.

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, WAS 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. Manage nodes describes how to create a node.
A Web server definition is created.
We can also use either use the administrative console or use the ConfigureWebServerDefintion.jacl script to create a Web server definition. If you use the administrative console:

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.
Use the wizard to complete the Web server definition.

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.
Master repository is updated and saved.

When you install a plug-in, the configuration file for that plug-in is automatically created. We 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.

Before you begin

Install your Web server if it is not already installed.
If you want to use an IBM HTTP Server, see Installing IBM HTTP Server. Otherwise, see the installation information provided with your Web server.
Ensure that your Web server is configured to perform operations required by Web applications, such as GET and POST. Typically, this involves setting a directive in the Web server configuration file (such as the httpd.conf file for an IBM HTTP Server). Refer to the Web server documentation for instructions. If an operation is not enabled when a servlet or JSP file requiring the operation is accessed, an error message displays, such as this one from the IBM HTTP Server:
HTTP method POST is not supported by this URL.

Make sure the appropriate plug-in file has been installed on your Web server and the configureWeb_servername script has been run to create and configure the Web server definition for this Web server.
If you are using a distributed platform Web server, use the Plug-in Installation wizard to install the appropriate plug-in file to your Web server. Then run the configureWeb_servername script created by the wizard to create and configure the Web server definition in the configuration repository.

Procedure

Use the administrative 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

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

Select Servers > Web Servers > webserver > plug-in properties.
Select Automatically generate plug-in configuration file or click on one or more of the following topics to manually configure the plugin-cfg.xml file:

Caching
Request and response
Request routing
Service
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.
Click OK.
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.

Optional: Edit the plug-in configuration file. You should not have to edit the configuration file. However, if you do, remember that the file is in ASCII format (ISO-98859-1). Issue the following command to convert the file to EBCDIC format
> iconv -f ISO8859-1 -t IBM-1047 plugin-cfg.xml.ASCII > plugin-cfg.xml.EBCDIC

Edit the file, and then issue the following command to convert it back to ASCII format:

> iconv -f IBM-1047 -t ISO8859-1 plugin-cfg.xml.EBCDIC > plugin-cfg.xml.ASCII

Remember that any manual changes you make to the file will be overwritten the next time the file is regenerated.
Optional: 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, if one does not already exist there. See Configuring the Web server plug-in for Secure Sockets Layer for information on how to configure GSKIT.
Optional: If you want to enable the Web server plug-in to use private headers, define an SSL configuration repertoire that defines a trust file. Then in the administrative console, select Application servers > server1 > Web Container Settings > Web Container Transport Chains > transport_chain > SSL Inbound Channel (SSL_2) and specify this repertoire for that transport chain. If you try to use private headers without setting up an SSL configuration repertoire that does not include a trust file definition, the private headers will be ignored. If the private headers are ignored, the application server might not locate the requested application.
After you enable the use of private headers, the transport chain's SSL inbound channel trusts all private headers it receives. Therefore, ensure that all paths to the transport chain's SSL inbound channel are trusted.
Tune your Web server using Web server tuning parameters.
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 v6 that has a running IBM HTTP Server Administrative 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.
The remote Web server installation location is the location you specified when you created the node for this Web server.

Result
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. We 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 one 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 > servername > 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.

See also

Web server plug-in properties settings
Web server plug-in custom properties
Web server plug-in configuration service properties settings
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
Checking your IBM HTTP Server version
Plug-ins: Resources for learning
Web server plug-in tuning tips
Private headers
plugin-cfg.xml file
Gskit install images files

See Also

Transport chains

Related Tasks

Configuring transport chains
Changing the HTTP plug-in configuration
Tuning Web servers