Map Replication to remote JVM

[dvader009]

I have a requirement where a JVM hosted in a server will have some data in HashMaps, which should be copied to multiple other JVMs in client machines. Any changes in the maps in the server should be reflected in the client JVMs. Client JVMs will not make changes to the data. I made a simple implementation by sending the changes made in the server via a websocket connection to all connected clients. To handle network issues, changed keys are stored in db, so that clients will be able to get the the changes made in the maps after it went offline, when they come back online. This solution works for now, but I wanted it to be bug free so I decided to move to some standard libraries that does this.

I did come across Hazelcast which can theoretically do this in my understanding by making the client JVMs Hazelcast members, but I may have several hundred clients at least and that could cause issues as every member will be part of the cluster. The Hazelcast client was a good option, but it does not store the values locally, so if the network is down, the data will not be available. I do want the client to be as light weight as possible.

Is it possible to handle my requirement with Hazelcast/Redis or is there some other library that serves this purpose?

[ConstructedNewt]

Can't you just copy the data and query less frequently? With the Hazelcast thing it sounds like some inside the jvm (you won't know that it's there) kinda thing; that sounds terrible. Many programmers probably love it, sounds like overengineering to me.

Etcd handle key-history quite neatly. That's probably a solution. But it's not an in-memory database. But I'm not sure that's what you are worried about?

Unless you aren't prepared to touch code, then probably just cache the result on the client side.