Spring Integration Expert

I am looking for somebody who is very experienced with Spring Integration and provide quick help to set Spring Integration in our java application. The application uses Spring framework. Today we have different ways to handle events but they are pretty much integrated in the application code. I would like to isolate event handling handling from the code - and to maintain a separation of concerns, and also allow us to easily configure future eventing architecture without changing the application code. We are not going to change all existing event handling right now. But we are in the process of implementing new events that are to be pushed to clients and I thought we could start with Spring Integration for these new event handling. This new event handling is a publish-subscribe style and if it should be suggested if there is special support for that with Spring Integration or if we need to implement ourselves. The project involves also to help our developer to set up the SI so we can use it to send the new event messages to a client over HTTP as well sending the event messages as email. The freelancer should also set up units tests for the above task. So the project involves setting up Spring Integration, helping our developer to implement the feature and set up units test + documenting what you do. It is difficult to set up a time effort for this at this point. I guess it would be possible after have discussed further about the project with the coder.