CloneID
 Technote (FAQ)
 
Problem
What is the CloneID and how it works?
 
 
Solution
In WebSphere V4.0, each CloneID (also known as server ID) is appended to the session ID. When an HTTP session is created, its ID is passed back to the browser as part of a cookie or URL encoding.

Size of CloneID for two clones are different: 8 and 9 characters.


This CloneID is only visible from <websphere_install_root>/config/plugin-cfg.xml.

Ex:
<ServerGroup Name="Session App Server">
<Server CloneID="t0im8jfe" Name="Session App Server">
<Transport Hostname="itsohost" Port="9081" Protocol="http"/>
</Server>
</ServerGroup>

CloneID used in conjunction with Session Affinity. When this attribute is set, the plug-in will check the incoming cookie header or URL for jsessionid. If the jsessionid is found, then the plug-in will look for a CloneID or CloneIDs. If CloneIDs are found and a match is made to this attribute, then the request will be sent to this server rather than being load balanced across the server group.

This CloneID is generated automatically and NOT configurable from any admin tool (console/wscp/xmlConfg) .Changing the CloneID in "plugin-cfg.xml" to some thing different than system generated, will break the session affinity.

If you are not using Session Affinity, then it is best to remove these CloneIDs from the configuration because there is added request processing in the plug-in when these are set. If CloneIDs are not in the plug-in, then it is assumed that session affinity is not on and the request is load balanced across the server group.




Cookie consist of --> cacheID + sessionid +CloneID and the length of character is 4 + 23 + 8
Here the "cacheID" and "sessionid" lengths are fixed but, not the "CloneID" .

Cookie Name
A unique name for the cookie. You can name the cookie JSESSIONID as specified in the Servlet 2.2 API, but the name can also be modified. To modify the cookie name in the administrative console, select the Application Server > Session Manager Service > Click Edit Properties. From the Session Manager Service panel, click Help. See the Cookie Name section.
 
Related information
IBM WebSphere V4.0 Advanced Edition Handbook
How to Change CloneSeparator?
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Sessions and Session Management
Operating system(s): AIX
Software version: 4.0.7
Software edition:
Reference #: 1203879
IBM Group: Software Group
Modified date: Apr 18, 2005