communication between spring instances behind a load balancer

Question

I have a few instances of Spring apps running behind a load balancer. I am using EHCache as a caching system on each of these instances.

Let's say I receive a request that is refreshing a part of the cache on one instance. I need a way to tell the other instances to refresh their cache (or to replicate it).

I'm more interested in a solution based on Spring and not just cache replication and that's because there are other scenarios similar with this one that require the same solution.

How can I achieve this?

Answer 1

There is no simple Spring solution for this. Depends on the requirements. You can use any kind of PubSub like a JMS topic to notify your nodes. This way the problem can be that you cannot guarantee consistency. The other nodes can still read the old data for a while. In my current project we use Redis. We configured it as cache with Spring Data Redis and theres no need to notify the other nodes since the cache is shared. In non cache scenarios we also use redis as a PubSub service.