/*
* Copyright (c) OSGi Alliance (2012). All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.osgi.framework.namespace;
import org.osgi.resource.Namespace;
/**
* Host Capability and Requirement Namespace.
*
* <p>
* This class defines the names for the attributes and directives for this
* namespace. All unspecified capability attributes are of type {@code String}
* and are used as arbitrary matching attributes for the capability. The values
* associated with the specified directive and attribute keys are of type
* {@code String}, unless otherwise indicated.
*
* <p>
* Unless otherwise noted, all directives specified on the
* {@code Bundle-SymbolicName} header are visible in the capability and all
* directives specified on the {@code Fragment-Host} header are visible in the
* requirement.
*
* <ul>
* <li>The {@link Namespace#CAPABILITY_USES_DIRECTIVE uses} directive must be
* ignored. A {@code uses} directive specified on the
* {@code Bundle-SymbolicName} header must be ignored. A {@code uses} directive
* must not be present in the capability.</li>
* <li>The {@link Namespace#CAPABILITY_EFFECTIVE_DIRECTIVE effective}
* {@link Namespace#REQUIREMENT_EFFECTIVE_DIRECTIVE directives} must be ignored.
* This namespace is only effective at {@link Namespace#EFFECTIVE_RESOLVE
* resolve} time. An {@code effective} directive specified on the
* {@code Bundle-SymbolicName} or {@code Fragment-Host} headers must be ignored.
* An {@code effective} directive must not be present in a capability or
* requirement.</li>
* <li>The {@link Namespace#REQUIREMENT_CARDINALITY_DIRECTIVE cardinality}
* directive has limited applicability to this namespace. A {@code cardinality}
* directive specified on the {@code Fragment-Host} header must be ignored. All
* requirements must have the {@code cardinality} directive set to
* {@link Namespace#CARDINALITY_MULTIPLE multiple}.</li>
* </ul>
*
* <p>
* A non-fragment resource with the with the
* {@link IdentityNamespace#TYPE_BUNDLE osgi.bundle} type
* {@link IdentityNamespace#CAPABILITY_TYPE_ATTRIBUTE identity} provides zero or
* one<sup>†</sup> host capabilities. A fragment resource with the
* {@link IdentityNamespace#TYPE_FRAGMENT osgi.fragment} type
* {@link IdentityNamespace#CAPABILITY_TYPE_ATTRIBUTE identity} must not declare
* a host capability and must declare exactly one host requirement.
* <p>
* † A resource with no bundle symbolic name must not provide a host
* capability.
*
* @Immutable
* @version $Id: aa3cc744c7b9c21d908260f456567ab8a6de1430 $
*/
public final class HostNamespace extends AbstractWiringNamespace {
/**
* Namespace name for host capabilities and requirements.
*
* <p>
* Also, the capability attribute used to specify the symbolic name of the
* host.
*
*/
public static final String HOST_NAMESPACE = "osgi.wiring.host";
/**
* The capability directive identifying if the resource is a singleton. A
* {@code String} value of "{@code true}" indicates the resource
* is a singleton; any other value or {@code null} indicates the resource is
* not a singleton.
*
* <p>
* This directive should be examined using the {@link IdentityNamespace
* identity} namespace.
*
* @see IdentityNamespace#CAPABILITY_SINGLETON_DIRECTIVE
*/
public static final String CAPABILITY_SINGLETON_DIRECTIVE = "singleton";
/**
* The capability directive identifying if and when a fragment may attach to
* a host bundle. The default value is {@link #FRAGMENT_ATTACHMENT_ALWAYS
* always}.
*
* @see #FRAGMENT_ATTACHMENT_ALWAYS
* @see #FRAGMENT_ATTACHMENT_RESOLVETIME
* @see #FRAGMENT_ATTACHMENT_NEVER
*/
public static final String CAPABILITY_FRAGMENT_ATTACHMENT_DIRECTIVE = "fragment-attachment";
/**
* The directive value indicating that fragments are allowed to attach to
* the host bundle at any time (while the host is resolved or during the
* process of resolving the host bundle).
*
* @see #CAPABILITY_FRAGMENT_ATTACHMENT_DIRECTIVE
*/
public static final String FRAGMENT_ATTACHMENT_ALWAYS = "always";
/**
* The directive value indicating that fragments are allowed to attach to
* the host bundle only during the process of resolving the host bundle.
*
* @see #CAPABILITY_FRAGMENT_ATTACHMENT_DIRECTIVE
*/
public static final String FRAGMENT_ATTACHMENT_RESOLVETIME = "resolve-time";
/**
* The directive value indicating that no fragments are allowed to attach to
* the host bundle at any time.
*
* @see #CAPABILITY_FRAGMENT_ATTACHMENT_DIRECTIVE
*/
public static final String FRAGMENT_ATTACHMENT_NEVER = "never";
/**
* The requirement directive used to specify the type of the extension
* fragment.
*
* @see #EXTENSION_FRAMEWORK
* @see #EXTENSION_BOOTCLASSPATH
*/
public final static String REQUIREMENT_EXTENSION_DIRECTIVE = "extension";
/**
* The directive value indicating that the extension fragment is to be
* loaded by the framework's class loader.
*
*
* @see #REQUIREMENT_EXTENSION_DIRECTIVE
*/
public final static String EXTENSION_FRAMEWORK = "framework";
/**
* The directive value indicating that the extension fragment is to be
* loaded by the boot class loader.
*
* @see #REQUIREMENT_EXTENSION_DIRECTIVE
*/
public final static String EXTENSION_BOOTCLASSPATH = "bootclasspath";
/**
* The requirement directive used to specify the visibility type for a
* requirement.
*
* <p>
* This directive should be examined using the {@link BundleNamespace
* bundle} namespace.
*
* @see BundleNamespace#REQUIREMENT_VISIBILITY_DIRECTIVE
*/
public final static String REQUIREMENT_VISIBILITY_DIRECTIVE = "visibility";
private HostNamespace() {
// empty
}
}