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Loosing session between 2 webservers in a cluster

Itai Sadan
Occasional Visitor

Loosing session between 2 webservers in a cluster

The problem: We have two webservers in a cluster and an alias name that transfers requests to one of the servers (based on the setting of cluamgr). During an HTTP session with one of the web servers (A), suddenly one of the HTTP requests is referred to the other web server (B), although the intention was to implement a sticky session. At this point I receive an invalid session error since server B was not suppose to take part in this session.

Env. Architecture:

WebServer A
Application Server
WebServer B

The WebServers are iPlanet 6.0 servers residing on two different machines of type HP Tru64 Unix.
The application server is weblogic 6.1.

Env. Configuration:

On each HP the configuration of the following two files is similar:

FILE 1: clua_services
# The port of the webserver is 50000
http 50000/udp in_multi
http 50000/tcp in_multi

FILE 2: clu_alias.config
/usr/sbin/clumgr -a selw=6,selp=5,join,alias=DEFAULTALIAS

Is defining the http port 50000 as in_multi and not in_single correct?

Ralf Puchner
Honored Contributor

Re: Loosing session between 2 webservers in a cluster

you have installed a multi instance webserver (each member hosts an instance of the iplanet). In this case the requests are spread between the members and processed by each member. This is a problem if using data from previous requests (e.g. Instance-Handles).
So the problem is the sharing of the instance handling depending on the logic of the web application. The connection from client-side is opened and closed so each HTTP requests leads to a new connection/socket-Id.

In your case it seems be better to configure the iplanet webserver as a single instance application or to change the web application to use a mechanism to share the handles between the two iplanet instances.

read the description of the in_multi and in_single within the clua_services man-page and you will come to the conclusion this will not solve your problem.
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