Non-Clustered IS Nodes with shared db pools

I came across a configuration where a client had a few IS Nodes(not clustered ) with the same database pools (for Core audit,central users etc) and connected to the Univirsal messaging

I would like know what would happen to triggers subscribing to Topics on UM would behave?

As far as theory tells me …All 3 nodes will subscribe to a copy of the of the document and process it,

In a past project with a client whenever there was a clustering problem on the ISs…the first thing I would check is wehter there were any duplicate processing that happened because one IS knew not what the other was doing.But I didn’t ever see that happening.

So Im wondering if my understanding is incorrect
Am I missing something?

For Stateless Cluster , the following should be set
If using Native messaging : For Universal Messaging (Nirvana), you need Integration Server 9.5 SP1 or above. Ensure all ISs have the same configuration for the shared Universal Messaging Connection Alias, and have “Shared Client Prefix”=yes.

While Using JMS Connection Alias : If using Topic , proper durable subscribers should be created with shared state as true. So, that only one server gets the copy of the message…A trigger client object will be created with a client id. The client object will be shared by all the integration server nodes as they interact with same UM.

Theoretically , When using only topic , as the message is broadcasted , all the active subscribers will get the copy of messages.

Let’s hear from other forum members with their views on the same.

Thanks Rakesh…That is the right answer…I just realized that terracotta might be an overkill if you really dont have any other caching requirements other than clustering.

A good Load balancer balancing a statesless cluster should be enough for 80 % use cases out there,