Invoke Different Service based on message type

My input is from a NLP system. based on clustering it sends me a messagetype on which I have to invoke a webservice. I need to accommodate addition of new messagetype and service.

How to design it such that the code changes to add new messageType and service is minimal. Can this be done without restart of servers.

Example Messages:
<Msg1> should be routed to <Service1>
<Msg2> should be routed to <Service2>
<Msg3> should be routed to <Service3>
        .   .   .   .   .
        .   .   .   .   .
<Msg-N> should be routed to <Service-N>

Some things i thought through is to keep the mapping of MessageType and service in config file and load it to memory if i there are config changes.