If you are a web services developer or your current assignment requires you to write web services then RESTful web services is what you should look for. There are enormous tools which can help you to write REST web services.
Here is a list of tools which are most widely used to write java based RESTful web services.
Each one of them has its own advantages and disadvantages. Of the tools listed here for creating RESTful web services, I like CXF the most. This is primarily because it simply gets mixed up easily with Spring based applications. Though Spring also has support for RESTful web services but if you don't want to use Spring framework in your application then also CXF can be used to build REST web services.
I have also used RESTLET framework for creating REST based web service and it is very simple to use. The earlier version of Restlet depended on XML configuration but latest versions make use of annotations very well.