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What is New in JAX-RS 2.0

Filters

Server

ContainerRequestFilter and ContainerResponseFilter are new server-side request and response filters which can be used to customize various properties of a given request and response.

ContainerRequestFilter annotated with a PreMatching annotation will be run before the runtime has matched a request to a specific JAX-RS root resource and method. Prematching filters can be used to affect the matching process.

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ContainerRequestFilter can be used to block a request.

The filters can be bound to individual resource methods only with the help of custom NameBindings.

Multiple request and response filters can be executed in the specific order by using javax.annotation.Priority annotations. See Priorities for more information. Request filters are sorted in the ascending order, response filters - in the descending order.

Client

ClientRequestFilter and ClientResponseFilter are new client-side request and response filters which can be used to customize various properties of a given request and response.

ClientRequestFilter can be used to block a request.

Request filters are sorted in the ascending order, response filters - in the descending order. See Priorities for more information.

Interceptors

ReaderInterceptor and WriterInterceptor can be used in addition to filters or on its own to customize requests and responses on server and client sides.

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The interceptors used on the server side can be bound to individual resource methods only with the help of custom NameBindings.

All interceptors are sorted in the ascending order. See Priorities for more information.

Dynamic Features

Dynamic Feature is a server side feature that can be used to attach request and response filters as well as reader and writer interceptors to specific resource methods. It is an alternative approach to using the NameBindings and offer a finer-grained control over the binding process.

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Dedicated exception classes representing various HTTP error or redirect conditions have been introduced, see the 'javax.ws.rs' Package Exceptions section.

For example, instead of throwing a "new WebApplicationException(404)" one is better to do "new NotFoundException()". The finer-grained exception hierarchy allows for a finer-grained support of exception mappers. It also opens a way to check WebApplicationException and all of its subclasses when catching the HTTP exceptions on the client side.

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One of the best JAX-RS 2.0 features is the support for server-side asynchronous invocations. Please see the AsyncResponse documentation which provides a very good overview of this feature.

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Another approach is to have AsyncResponse suspended for a limited period of time only and also register a TimeoutHandler. The latter will be invoked when the invocation is resumed by the container after the timeout has expired and the handler will either complete the invocation or suspend it again till it is ready to finish it.

CompletionCallback can be registered with AsyncResponse to receive the notifications when the async response has been sent back.

ConnectionCallback is supported starting from CXF 3.0.0-milestone2.

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Please also see the page about CXF Continuations API which JAX-RS 2.0 AsyncResponse implementation is based upon and
how to configure CXFServlet.

Parameter converters

ParamConverterProvider can be used to manage the conversion of custom Objects to String and vice versa on the server and client sides, when processing JAX-RS parameters representing URI parts or headers or form elements and when a default conversion mechanism does not work. For example, java.util.Date constructor accepting a String may have to be replaced a custom ParamConverter.

Bean parameters

BeanParam can be used to get JAX-RS parameters representing URI parts or headers or form elements and also contexts injected into a single bean container.

Note the CXF extension supporting the injection of all the parameters of specific JAX-RS type (example, QueryParam("") MyBean) is different, it only allows to get all the query parameters injected, but it also does not require that bean properties are annotated with QueryParam/etc annotations.

ResourceInfo

ResourceInfo is a new JAX-RS context which can be injected into filters and interceptors and checked which resource class and method are about to be invoked.

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Subresources can get JAX-RS contexts injected directly into their fields with the help of ResourceContext.

When possible, having a parent resource injecting the contexts into a given subresource instance via a setter or constructor can offer a much simpler alternative.

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In JAX-RS 1.1 a request with URI such as "/1" is not guaranteed to be matched and in CXF 2.7.x or earlier the use of CXF specific ResourceComparator is required to ensure Root1 and its get() method gets selected. In CXF 3.0.0 Root1 get() will always be correctly selected. Note ResourceComparator may still be of help in some cases even in CXF 3.0.0.

Link

Link is a utility class for building HTTP links as HTTP Link headers or application data links.
UriInfo, UriBuilder, Response and ResponseBuilder classes have been enhanced to support Link.

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Response Streaming 

JAX-RS StreamingOutput

StreamingOutput can be used to stream the data to the client, for example:

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