A colleague of mine Fabio Filardi has published his work on Github. It has two samples for the Expense services and UserSession services. He has documented it really well. Get onto it if you are going to expose your web services as RESTful. It does save you a lot of time.
Github project
https://github.com/ffilardi/AxaptaAPI
Documentation under wiki
https://github.com/ffilardi/axaptaapi/wiki
Here are some additional notes. Microsoft has documented it really well too. So, get your head around the concepts and the above links should be of great benefit to you.
This is a good summary of the Azure service bus adapter with AX.
http://blogs.msdn.com/b/aif/archive/2013/04/29/aif-windows-azure-service-bus-adapter.aspx
Whitepaper from Microsoft on how to extend it. Microsoft provides an example by talking about mobile app. Concept is how to expose your web services securely outside the domain.
https://www.microsoft.com/en-us/download/details.aspx?id=38413
Fabio has written a blog on one of the on this topic last year.
http://www.uxceclipse.com.au/Pages/Blog-Detail.aspx?newslist=Blog%20List&itemId=81
Be aware of the licensing cost for Azure. This is from Microsoft blog about the cost associated with Azure service bus.