• Intro Headers Instructions Macros Commands
Fork me on GitHub
    • Getting Started
      • Introduction
      • How to install bnd
      • Guided Tour Workspace & Projects
      • bnd / bndlib Features and JAR Wrapping Techniques
      • FAQ - Frequently Asked Questions
    • Concepts and Practices
      • Concepts
      • Background
      • Best practices
    • Build and Development
      • Build
      • Generating JARs
      • Versioning
      • Baselining
      • Service Components
      • Metatype
      • Contracts
      • Bundle Annotations
      • Accessor Properties
      • SPI Annotations
    • Dependency and Launching
      • Resolving Dependencies
      • Launching
      • Startlevels
    • Testing
      • Testing
      • Testing with Launchpad
    • Packaging and Distribution
      • Packaging Applications
      • JPMS Libraries
      • Wrapping Libraries to OSGi Bundles
    • Documentation and Tools
      • Generating Documentation
      • bnd CLI Commands
      • For Developers
      • Templates for Workspaces
      • Tips for Windows users
      • Tools bound to bnd
    • Reference Material
      • Reference
      • Headers
      • Instruction Reference
      • Instruction Index
      • Macro Reference
      • Macro Index
      • Plugins
      • External Plugins
    • Configuration and Troubleshooting
      • Settings
      • Errors
      • Warnings
  • Require-Capability ::= requirement ( ',' requirement )*

    Prev Next
    Header
    Specifies that a bundle requires other bundles to provide a capability

    • Example: Require-Capability: com.microsoft; filter:='(&(api=win32)(version=7))'

    • Pattern: .*

    Options

    • effective: (resolve) 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. Additonal names for the effective directive should be registered with the OSGi Alliance.
      • Example: effective:=resolve

      • Values: resolve or another word

      • Pattern: .*

    • resolution: (mandatory optional) 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.
      • Example: resolution:=optional

      • Values: mandatory,optional

      • Pattern: mandatory|optional

    • filter: (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.
      • Example: filter:= (&(a=1)(b=2))

      • Pattern: .*



    Require-Capability

    The Require-Capability header declares that a bundle requires one or more OSGi capabilities to be present in the runtime environment. Each requirement can specify a namespace, filter, and other attributes or directives.

    Example:

    Require-Capability: osgi.extender;filter:='(osgi.extender=osgi.component)'
    

    This header is used for advanced modularity and service scenarios, and is typically generated by annotations or build tooling.

    			Parameters requirements = new Parameters(annotationHeaders.getHeader(REQUIRE_CAPABILITY));
    		Parameters capabilities = new Parameters(annotationHeaders.getHeader(PROVIDE_CAPABILITY));
    
    		//
    		// Do any contracts contracts
    		//
    		contracts.addToRequirements(requirements);
    
    		//
    		// We want to add the minimum EE as a requirement
    		// based on the class version
    		//
    
    		if (!isTrue(getProperty(NOEE)) //
    				&& !ees.isEmpty() // no use otherwise
    				&& since(About._2_3) // we want people to not have to
    										// automatically add it
    				&& !requirements.containsKey(ExecutionEnvironmentNamespace.EXECUTION_ENVIRONMENT_NAMESPACE) // and
    																											// it
    																											// should
    																											// not
    																											// be
    																											// there
    																											// already
    		) {
    
    			JAVA highest = ees.last();
    			Attrs attrs = new Attrs();
    
    			String filter = doEEProfiles(highest);
    
    			attrs.put(Constants.FILTER_DIRECTIVE, filter);
    
    			//
    			// Java 1.8 introduced profiles.
    			// If -eeprofile= auto | (<profile>="...")+ is set then
    			// we add a
    
    			requirements.add(ExecutionEnvironmentNamespace.EXECUTION_ENVIRONMENT_NAMESPACE, attrs);
    		}
    
    		if (!requirements.isEmpty())
    			main.putValue(REQUIRE_CAPABILITY, requirements.toString());
    
    
    	/*
     * Require-Capability header
     */
    private void doRequireCapability(RequireCapability annotation) {
    	StringBuilder sb = new StringBuilder(annotation.ns());
    	if (annotation.filter() != null)
    		sb.append(";filter:='").append(annotation.filter()).append("'");
    	if (annotation.effective() != null)
    		sb.append(";effective:='").append(annotation.effective()).append("'");
    	if (annotation.resolution() != null)
    		sb.append(";resolution:='").append(annotation.resolution()).append("'");
    
    	if (annotation.value() != null)
    		sb.append(";").append(annotation.value());
    
    	add(Constants.REQUIRE_CAPABILITY, sb.toString());
    }
    
    
    package aQute.bnd.annotation.headers;
    
    	import java.lang.annotation.*;
    	
    	/**
    	 * The Bundle’s Require-Capability header
    	 * 
    	 * {@link About}
    	 */
    	@Retention(RetentionPolicy.CLASS)
    	@Target({
    			ElementType.ANNOTATION_TYPE, ElementType.TYPE
    	})
    	public @interface RequireCapability {
    		String value() 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
    		 * <a href="https://www.osgi.org/developer/specifications/reference/">OSGi Reference
    		 * Page</a>
    		 */
    		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();
    	
    		/**
    		 * 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;
    	
    	}
    	
    	
    		private void verifyRequirements() {
    	Parameters map = parseHeader(manifest.getMainAttributes().getValue(Constants.REQUIRE_CAPABILITY));
    	for (String key : map.keySet()) {
    		Attrs attrs = map.get(key);
    		verify(attrs, "filter:", FILTERPATTERN, false, "Requirement %s filter not correct", key);
    
    		String filter = attrs.get("filter:");
    		if (filter != null) {
    			String verify = new Filter(filter).verify();
    			if (verify != null)
    				error("Invalid filter syntax in requirement %s=%s. Reason %s", key, attrs, verify);
    		}
    		verify(attrs, "cardinality:", CARDINALITY_PATTERN, false, "Requirement %s cardinality not correct", key);
    		verify(attrs, "resolution:", RESOLUTION_PATTERN, false, "Requirement %s resolution not correct", key);
    
    		if (key.equals("osgi.extender")) {
    			// No requirements on extender
    		} else if (key.equals("osgi.serviceloader")) {
    			verify(attrs, "register:", PACKAGEPATTERN, false,
    					"Service Loader extender register: directive not a fully qualified Java name");
    		} else if (key.equals("osgi.contract")) {
    
    		} else if (key.equals("osgi.service")) {
    
    		} else if (key.equals("osgi.ee")) {
    
    		} else if (key.startsWith("osgi.wiring.") || key.startsWith("osgi.identity")) {
    			error("osgi.wiring.* namespaces must not be specified with generic requirements/capabilities");
    		}
    
    		verifyAttrs(attrs);
    
    		if (attrs.containsKey("mandatory:"))
    			error("mandatory: directive is intended for Capabilities, not Requirement %s", key);
    
    		if (attrs.containsKey("uses:"))
    			error("uses: directive is intended for Capabilities, not Requirement %s", key);
    	}
    }
    

    TODO Needs review - AI Generated content

Prev Next
Search
    • Home