My Experience with Java REST Frameworks (specifically Jersey and CXF)
Recently I was tasked with developing a server-side REST strategy for a client. When I started working with them, they were using GWT RPC for exposing services. They wanted to move to RESTful services to allow for a more open platform, that multiple types of clients could talk to. There were interested in supporting SOAP and GWT RPC as well, but it wasn't required. They are using Spring, a custom namespace (for easily creating remote services) and an HTML documentation generator to expose their API in human readable form.
When I first starting developing, I chose to try Enunciate. From Enunciate's homepage:
Enunciate is an engine for creating, maintaining, and deploying your rich Web service API on the Java platform. If that sounds complicated, it's not. All you have to do is define your service interfaces in Java source code. ... Then invoke Enunciate.
Sounds pretty sweet, eh? At first glance, the things I liked about Enunciate were:
- The ability to generate multiple endpoints (and clients).
- Generates nice-looking documentation.
- Allows selecting different frameworks (for example, CXF instead of JAX-WS RI).
Initially, the hardest part of using Enunciate was integrating it into my project. This was somewhat related to having a multi-module project, but moreso related to getting the settings right in my enunciate.xml file. After getting everything working, I encountered a few Spring wiring issues with the GWT Endpoints and with Jersey's Spring support.
The good news is I believe most of these issues were related to my project and how it proxies Spring beans that Jersey couldn't find. Jersey's Spring support only supports annotations at this time, so I was unable to tell it the proxied bean names via XML (or even its own annotations). I'm sure this problem is solvable, but after struggling with it for a day or two, I decided to give up on Enunciate. I had to get something working, and fast.
At this point, I was back to the drawing board. I knew there were plenty of good Java REST frameworks available, but Spring and CXF (for SOAP) were already available dependencies in my project, so I chose that route. I was able to get something up and running fairly quickly with this tutorial and CXF's JAX-RS documentation. I ran into an Invalid JSON Namespace issue, but was able to solve it by adding a custom namespace.
It's not all rosy though, there are still a couple CXF issues I haven't solved:
- I'd like to remove the namespace prefixes on returned JSON. I've never seen JSON with "prefix." notation before and it doesn't seem right.
- I'm unable to return String from services.
While CXF does take a bit of XML for each service, it's kinda slick in that it only requires you to annotate your service interfaces. It also generates documentation for your services (WSDL and WADL), but it's not as pretty as Enunciate's. To solve this, I added Enunciate for documentation only. To make Enunciate work, I did have to add some annotations to my service implementation classes and parse the generated HTML to fix some links to CXF's services, but ultimately it works pretty well.
In the end, I recommended my client not use Enunciate for generating endpoints. This was primarily related to their unique Spring configuration, but also because I was able to easily use the same classes for REST, SOAP and GWT Endpoints. However, I will continue to keep my eye on Enunciate. It could be very useful for the upcoming appfuse-ws archetype. I'm also eager to see better GWT support and the ability to generate Overlay types in future releases.