The router

JAX-RS is command-oriented. It means that a request must be bound to a Java method. To do so, the matching takes multiple parameters of the request into account:

• The patch
• The Accept header
• The Content-Type header

Here is the simplified algorithm for routing:

1. Find the class matching the request based on the path (this is a regex-like logic).
2. From the class found in step 1, find the method matching the request based on the path. (This is close to step 1 but applied to methods with subresource handling.)
3. From the methods found in step 2, find the one that will handle the request based on mime types (Accept/Content-Type headers). This level parses the media types to handle the quality of service options (q, qs, and so on) of the header.

This is not a complicated algorithm, but it is quite dynamic and depends on the incoming requests. So most of the time, it is done at runtime by the providers and can add a small overhead, which you can notice during benchmarks.