Package aQute.bnd.annotation.headers

Annotation Type RequireCapability

@Retention(CLASS)
@Target({ANNOTATION_TYPE,TYPE})
public @interface RequireCapability

The Bundle’s Require-Capability header

Typically used as a meta-annotation, i.e. an annotation placed on another annotation, which we will call the user-defined annotation. When the user-defined annotation is found on a class within the bundle, an entry in the Require-Capability header is added. The filter expression of the requirement may be parameterised with values from the user-defined annotation. For example, given the following declarations:

 @RequireCapability( ns = "com.acme.engine", effective = "active", filter = "(com.acme.engine=${type})") 
 public @interface Engine { String type(); }
 @Engine(type = "wankel") public class Vehicle { ... }
 

... the following header will be generated in MANIFEST.MF:

 Require-Capability:\ com.acme.engine; \ effective:=active; \
  filter:="(com.acme.engine=wankel)",\ ...
 

About

Required Element Summary

Required Elements

Modifier and Type	Required Element	Description
java.lang.String	ns	The capability namespace.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
java.lang.String	effective	Specifies the time a Requirement is considered, either 'resolve' (default) or another name.
java.lang.String	extra
java.lang.String	filter	A filter expression that is asserted on the Capabilities belonging to the given namespace.
Resolution	resolution	A mandatory Requirement forbids the bundle to resolve when the Requirement is not satisfied; an optional Requirement allows a bundle to resolve even if the Requirement is not satisfied.
java.lang.String	value

Element Detail

ns

java.lang.String ns

The capability namespace. For example: osgi.contract.

value

java.lang.String value

Default:

""

extra

java.lang.String extra

Default:

""

effective

java.lang.String effective

Specifies the time a Requirement is considered, either 'resolve' (default) or another name. The OSGi framework resolver only considers Requirements without an effective directive or effective:=resolve. Other Requirements can be considered by an external agent. Additional names for the effective directive should be registered with the OSGi Alliance. See OSGi Reference Page

Default:

"resolve"

filter

java.lang.String filter

A filter expression that is asserted on the Capabilities belonging to the given namespace. The matching of the filter against the Capability is done on one Capability at a time. A filter like (&(a=1)(b=2)) matches only a Capability that specifies both attributes at the required value, not two capabilties that each specify one of the attributes correctly. A filter is optional, if no filter directive is specified the Requirement always matches.

Default:

""

resolution

Resolution resolution

A mandatory Requirement forbids the bundle to resolve when the Requirement is not satisfied; an optional Requirement allows a bundle to resolve even if the Requirement is not satisfied. No wirings are created when this Requirement cannot be resolved, this can result in Class Not Found Exceptions when the bundle attempts to use a package that was not resolved because it was optional.

Default:

aQute.bnd.annotation.headers.Resolution.mandatory