Why custom annotations instead of JAX-RS (JSR-311) ones?

[simon-heinen]

What was the design decision not to use the JAX-RS (JSR-311) annotations and instead create custom ones?

I would like to share the REST interfaces between my backend and Android frontend to not write them twice but this isn't possible due to the custom annotations or am I wrong?

[JakeWharton]

Because JAX-RS annotations are specific to configuring a server, not a client. There's all kinds of annotations which don't make sense in the context of a client (@Consumes, @Produces, @Producer, @DefaultValue, @Context, etc.), the regex-based path matching was something we didn't not want to support, none of the annotations deal with serialization, and we didn't want the ability to define @Path parts on types.

I spent a few days researching this over a year ago back before we had our v1.0 and found all of the aforementioned problems. Ultimately the annotations were designed with only the concerns of a server, not a client, in mind.

[tbroyer]

Note that JAX-RS 2.0 repurposed the annotations for use on client side, quite successfully. That doesn't make them a good fit for Retrofit anyway though.

[ghost]

@simon-heinen did you found a way to reuse the interfaces?

[simon-heinen]

No but there are some possible ways: What you can do is create a version of retrofit where you modify the parser that it accepts both retrofit annotations and jax rs annotations which might be the best way or you add the retrofit annotations to your jax rs interfaces on the server side (which I wouldn't recommend;)