aQute.bnd.annotation.headers.RequireCapability Maven / Gradle / Ivy
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package aQute.bnd.annotation.headers;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
*
* 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)",\ ...
*
*
* {@link About}
*/
@Retention(RetentionPolicy.CLASS)
@Target({
ElementType.ANNOTATION_TYPE, ElementType.TYPE
})
public @interface RequireCapability {
String value() default "";
String extra() default "";
/**
* The capability namespace. For example: {@code osgi.contract}.
*/
String ns();
/**
* 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
*/
String effective() default "resolve";
/**
* 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 {@code (&(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.
*/
String filter() default "";
/**
* 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.
*/
Resolution resolution() default Resolution.mandatory;
}