Thread processing in EMS connection

Question

I am setting up a client and exchange project and both are connecting to a remote server. Exchange will connect to the server by EMS connection. While client will connect by FIX.

For the aim of building of black box testing, both client and exchange engine will be given some predefined testcases to send and receive to the server. I design the client engine with multithread processing to manipulate many testcases. Actually it is able to run succesfully.

For exchange engine, I wonder that multi thread is applicable in the context that the exchange engine just need to publish a message when it received msg from subscribed topic on server.

Flow of messages transmission:

Client-->SERVER-->Exchange FIX EMS

Exchange-->SERVER-->Client EMS FIX

Thanks if you can help me on this issue.