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This module provides integration with JSR-299 (Contexts and Dependency Injection for the Java EE platform)
Both the JAX-RS and CDI specifications introduce their own
component
model. On the one hand, every class placed in a CDI archive that
fulfills a set of basic constraints is implicitly a CDI bean. On
the
other hand, explicit decoration of your Java class with
@Path
or
@Provider
is required for it to become a JAX-RS component.
Without the
integration code, annotating a class suitable for being a CDI bean
with
JAX-RS annotations leads into a faulty result (JAX-RS component
not managed by CDI)
The
resteasy-cdi module is a bridge that
allows
RESTEasy
to work with class
instances obtained from the CDI
container.
During a web service invocation, resteasy-cdi asks the CDI container for the managed instance of a JAX-RS component. Then, this instance is passed to RESTEasy. If a managed instance is not available for some reason (the class is placed in a jar which is not a bean deployment archive), RESTEasy falls back to instantiating the class itself.
As a result, CDI services like injection, lifecycle management, events, decoration and interceptor bindings can be used in JAX-RS components.
A CDI bean that does not explicitly define a scope is
@Dependent
scoped by default.
This pseudo scope means that the bean adapts to the
lifecycle of
the bean it is
injected into. Normal scopes (request,
session,
application) are more suitable for JAX-RS components as they
designate component's lifecycle boundaries explicitly. Therefore, the
resteasy-cdi
module alters the default
scoping in
the following way:
If a JAX-RS root resource does not define a scope explicitly, it is bound to the Request scope.
If a JAX-RS Provider or
javax.ws.rs.Application
subclass
does not define a scope explicitly, it is bound to the
Application
scope.
Since the scope of all beans that do not declare a scope is modified by resteasy-cdi, this affects session beans as well. As a result, a conflict occurs if the scope of a stateless session bean or singleton is changed automatically as the spec prohibits these components to be @RequestScoped. Therefore, you need to explicitly define a scope when using stateless session beans or singletons. This requirement is likely to be removed in future releases.
CDI integration is provided with no additional configuration with JBoss AS 6-M4 and higher.
Provided you have an
existing RESTEasy application, all that needs to
be done is to
add the
resteasy-cdi jar into your project's
WEB-INF/lib
directory.
When using
maven, this can be achieve by defining the
following
dependency.
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-cdi</artifactId>
<version>${project.version}</version>
</dependency>
Furthermore, when running a pre-Servlet 3 container, the following context parameter needs to be specified in web.xml. (This is done automatically via web-fragment in a Servlet 3 environment)
<context-param> <param-name>resteasy.injector.factory</param-name> <param-value>org.jboss.resteasy.cdi.CdiInjectorFactory</param-value> </context-param>
When deploying an application to a Servlet container that does not support CDI out of the box (Tomcat, Jetty, Google App Engine), a CDI implementation needs to be added first. Weld-servlet module can be used for this purpose.