session management fails if SessionIdManager.workerName contains a dot (.)

Using HashSessionIdManager, I set the workerName to be the fqdn of the host. e.g. (host.domain.com)

After doing so, session lookups fail.

The problem comes from the HashSessionIdManager.getClusterId method...

public String getClusterId(String nodeId) 
{
    int dot=nodeId.lastIndexOf('.');
    return (dot>0)?nodeId.substring(0,dot):nodeId;
}

This problem is also seen in the JDBCSessionIdManager

The input nodeId argument will be "<sessionId>.host.domain.com". e.g. "1f2jo7j8m3d2h.host.domain.com"

The expected return value is "<sessionId>". e.g. "1f2jo7j8m3d2h"

However, the actual return value is "<sessionId>.host.domain.". e.g. "1f2jo7j8m3d2h.host.domain"

Since the return value is incorrect, AbstractSessionManager.getHttpSession fails to find the existing session, and a new session will end up being created.

A workaround is to avoid "." in the workerName.

I recommend either

1. Defending against "." (by replacing them with underscores or throwing an exception or something), OR
2. Documenting that workerName must not contain a dot ".".

You could also use indexOf instead of lastIndexOf, but then you'd need to ensure the <sessionId> does not contain a dot.