Before you begin
You must migrate prerequisite and corequisite programs to the levels required by WebSphere Application Server, Version 5.x. You must also identify ports in use in Version 4.0.x before you begin the Version 5.x installation, to avoid possible conflicts during coexistence. The first two steps in this task describe these activities.
Why and when to perform this task
You can install WebSphere Application Server Version 4.0.x and Version 5 on the same node. When the Version 5 installation wizard detects the Version 4.0.x installation, it displays the migration and coexistence panel, where you can select either option, both options, or neither option. If you select coexistence, the installation wizard displays the coexistence panel to ensure you install Version 5 without port conflicts.
Silent installation also supports configuring for coexistence silently. You can specify non-conflicting port assignments in the options response file, as described in Installing silently.
By default, there are port conflicts between Version 4.0.x and Version 5 that you must resolve. Also, if you migrate more than two Version 4.0.x nodes to Version 5, there are port conflicts that you must resolve, as described in the Setting up Version 5 coexistence topic.
Steps for this task
Refer to the
WebSphere Application Server detailed system
requirements
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27006921
site for current requirements.
Refer to the Port number settings in WebSphere Application Server versions topic to see a list of default port numbers, and where they are defined.
Inspect the configuration of the previous version:
xmlConfig -export config.xml -nodeName theNodeName
Review the config.xml file to look for <node action="update" name="nodename"> to find the appropriate node and port number assignments in the file. The installation wizard displays a default set of coexistence port numbers as suggested Version 5 port numbers. Change the values to ports that are not in use. The installation wizard uses whatever values you approve.
Change conflicting HTTP transport ports manually, if necessary.
To use the same Web server for both Application Server versions, you must first upgrade the Web server to the common level supported by both versions of the application server.
Follow this procedure to use the same Web server for both WebSphere Application Server versions.
The WebSphere Application Server, Version 5 plug-in acts as the routing agent to route requests to both versions.
Web context roots must be unique across Application Server versions. If there is a common context root across versions, requests are served by the plug-in instance that was last loaded.
If you have both Version 4.0.x Samples and Version 5 Samples in the file, you can access only the Version 5 Samples after merging the configuration files because there is one context root for Samples.
Whenever you modify the plugin-cfg.xml file for either version, you must manually merge the files again, to make a master file.
This is described in the Preparing to install and configure a Web server (tins_webserver) topic in the base Application Server information center.
Whenever you modify the plugin-cfg.xml file for either version, you must manually merge the files again, to make a master file.
What to do next
Return to Migrating and coexisting to continue.