New Redis based SessionManager implementation: redex-sm

["Jonathan S. Fisher" <ex...@gmail.com>]

Hello Tomcat friends,

We recently published to Maven Central (com.github.exabrial:redex-sm:1.0.2)
a new Tomcat SessionManager that stores your serialized Sessions in Redis
instance. Details and usage are available here:
https://github.com/exabrial/redex-sm

The advantage of using a SessionManager like this is you may scale your
cluster very easily with sticky sessions and perform rolling upgrades
without user interruption. Redis is a great fit for a session storage use
case as it's basically a network-enabled Map. Many implementations of the
Redis protocol are available and creating  fault-tolerant scalable setup is
a well-trodden path.

redex-sm is very fast and tries to do the minimal amount of work on the
request thread. If a server dies, the user's session is retrieved from
Redis. If a session is updated, an event is broadcast to tell other servers
to evict their copy of the session in memory. If the session is
invalidated, an event is broadcast and all nodes invalidate the session.

We created this because the venerable memached-session-manager is very out
of date, and the Redisson session manager has a very large dependency list
that it does not shade and combines into a single jar, causing classpath
conflicts.

There are a few improvements to be made such as supporting multiple tomcat
revisions, writing tests, and pooling/broadcasting enhancements. We'd love
to see your pull requests or just if you find it useful.

Thank you,
-- 
Jonathan | exabrial@gmail.com
Pessimists, see a jar as half empty. Optimists, in contrast, see it as half
full.
Engineers, of course, understand the glass is twice as big as it needs to
be.