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