I have a Queue and a service is already listening to it, but now there is a new requirement for a new service to be constructed with a similar message coming over that queue. If we change that queue object to a Topic, we will then have to add another subscriber for the new service. What’s the better way to do this?

You can do this with a QAlias pointing to a topic object. You can then add in as many additional subscribers as you need to have copies of each message. A blog post I wrote a few years back may be of interest to you. It was about changing from using queues, to publish/subscribe for event messages. They are but one example of messages that many different consumers might want to have a copy of.

Publish your MQ Event Messages

Please, ask any follow up questions you have after reading that.

Cheers
Morag