First release candidate of Weld 2.4

2016-8-19   release   Martin Kouba

I am pleased to announce the first release candidate of Weld 2.4 (CDI 1.2). See also the release details. Thanks to everyone involved in this release!

Removed dependency on

Weld does not depend on anymore (actually, Weld 3 does not depend on guava since 3.0.0.Alpha2). This significantly reduces the footprint of both Weld SE and Weld Servlet. The dependency is also not bundled with shaded artifacts for Weld SE and Weld Servlet.

Enhanced version of javax.enterprise.inject.Instance

Weld now provides org.jboss.weld.inject.WeldInstance - an enhanced version of javax.enterprise.inject.Instance. There are three additional methods - getHandler(), handlers() and isResolvable(). A handler allows to inspect the metadata of the relevant bean and to destroy the underlying contextual instance. isResolvable() is just a convenient method - a replacement for !isUnsatisfied() && !isAmbiguous(). For more details see also the reference guide.

WeldInstance is automatically available in Weld SE and Weld Servlet where the Weld API is always on the class path. It is also available in Weld-powered EE containers. In this case, users would have to compile their application against the Weld API and exclude the Weld API artifact from the deployment (e.g. use provided scope in Maven).

This functionality is based on a new proposal for CDI-589.

Veto AnnotatedType not annotated with bean defining annotation

Sometimes it might be useful to process all types during bootstrap, i.e. fire/observe ProcessAnnotatedType event for each Java class discovered, but veto types which are not annotated with a bean defining annotation. The main reason is that not all classes that meet all of the necessary conditions are intended to become beans. And so vetoing such types helps to conserve memory used by the container. Note that if you use bean-discovey-mode=annotated (implicit bean archive) then no ProcessAnnotatedType will be fired for any such type because it’s not discovered at all. And there might be portable extensions which use ProcessAnnotatedType to extract some important information from classes which are not beans.

Therefore, Weld allows to use bean-discovey-mode=all (explicit bean archive) and veto types without a bean defining annotation whose AnnotatedType#getJavaClass().getName() matches a regular expression. In other words, a type is vetoed if its name matches a regular expression and at the same time is not annotated with a bean defining annotation. This functionality is implemented as a built-in portable extension processing all types from all bean archives (it was already doable using an extension but we believe it’s more convenient to have this functionality out of the box).

This is a workaround for problems of bean-discovey-mode=annotated mentioned in CDI-420.

@ActivateRequestScope moved to Weld API

This interceptor binding can be used to activate the request scope within a business method invocation. It was previously part of the Weld SE but we believe it might be useful in any environment. See also WELD-2150.

Improved rolling upgrades support

Lenny Primak (a Weld community member - thanks for the report again!) struggled with rolling upgrades on certain application servers (Payara, GlassFish). Therefore, a new configuration property was introduced. This property allows to specify a delimiter which is used to abbreviate a bean archive identifier (which is usually derived from the archive name) before used as a part of an identifier of an internal component (such as bean). See also the reference guide and WELD-2064.

Events - reflect the output of CDI-494

This change reflects the clarification around Event operations - "A wildcard type is not considered an unresolvable type variable". See also WELD-2137 and CDI-494. Simply said, the snippet below and similar ones should now work:

@Inject Event<List<?>> event;

public void fireLists() {
  List<String> stringList = new ArrayList<>();;
  List<Integer> intList = new ArrayList<>();;

void observeAllLists(@Observes List<?> anyList) {
  // Will be notified

Probe - allow to filter unused beans

The Probe development tool now identifies beans which are most likely unused (a bean is considered unused if it has no direct dependents, does not declare any observer or producer methods, is not annotated with @Named and is not a built-in bean, extension, interceptor or decorator). This might be useful to identify types suitable for vetoing as mentioned in Veto AnnotatedType not annotated with bean defining annotation.


Weld has underwent an internal cleanup. A lot of deprecated and unused classes were removed.

Initial Java 9 support

It’s now possible to build Weld with Java 9. Note that this does not mean that Weld is modularized in a Jigsaw way. It’s just the first step on a long road ;-).


Last but not least - a few bugs were killed. Weld SE - provided ClassLoader is also used to load extensions (WELD-2209). AnnotatedTypeValidator does consider extended interfaces (WELD-2221). Invocation of a JDK8 default method should be intercepted (this only works if using jboss-classfilewriter 1.2.0.Beta1+, WELD-2093).

WildFly Patch

As usual, a patch for WildFly is available. This time the target platform is WildFly 10.0.0.Final. If you’re not familiar with patching WildFly, check Markus’s tutorial.