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 * This code is distributed in the hope that it will be useful, but WITHOUT

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

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package com.sun.xml.internal.ws.api.server;

import java.util.Collection;

import java.util.Collections;

import java.util.Set;

import java.util.concurrent.CopyOnWriteArraySet;

import com.sun.istack.internal.NotNull;

import com.sun.xml.internal.ws.api.Component;

import com.sun.xml.internal.ws.api.ComponentEx;

import com.sun.xml.internal.ws.api.ComponentRegistry;

/**

 * Root of the SPI implemented by the container

 * (such as application server.)

 *

 * <p>

 * Often technologies that are built on top of JAX-WS

 * (such as Tango) needs to negotiate private contracts between

 * them and the container. This interface allows such technologies

 * to query the negotiated SPI by using the {@link #getSPI(Class)}.

 *

 * <p>

 * For example, if a security pipe needs to get some information

 * from a container, they can do the following:

 * <ol>

 *  <li>Negotiate an interface with the container and define it.

 *      (let's call it <tt>ContainerSecuritySPI</tt>.)

 *  <li>The container will implement <tt>ContainerSecuritySPI</tt>.

 *  <li>At the runtime, a security pipe gets

 *      {@link WSEndpoint} and then to {@link Container}.

 *  <li>It calls <tt>container.getSPI(ContainerSecuritySPI.class)</tt>

 *  <li>The container returns an instance of <tt>ContainerSecuritySPI</tt>.

 *  <li>The security pipe talks to the container through this SPI.

 * </ol>

 *

 * <p>

 * This protects JAX-WS from worrying about the details of such contracts,

 * while still providing the necessary service of hooking up those parties.

 *

 * <p>

 * Technologies that run inside JAX-WS server runtime can access this object through

 * {@link WSEndpoint#getContainer()}. In the client runtime, it can be accessed from

 * {@link ContainerResolver#getContainer()}

 *

 * @author Kohsuke Kawaguchi

 * @see WSEndpoint

 */

public abstract class Container implements ComponentRegistry, ComponentEx {

        private final Set<Component> components = new CopyOnWriteArraySet<Component>();

    /**

     * For derived classes.

     */

    protected Container() {

    }

    /**

     * Constant that represents a "no {@link Container}",

     * which always returns null from {@link #getSPI(Class)}.

     */

    public static final Container NONE = new NoneContainer();

    private static final class NoneContainer extends Container {

    }

    public <S> S getSPI(Class<S> spiType) {

        for (Component c : components) {

                S s = c.getSPI(spiType);

                if (s != null)

                        return s;

        }

        return null;

    }

        public Set<Component> getComponents() {

                return components;

        }

        public @NotNull <E> Iterable<E> getIterableSPI(Class<E> spiType) {

        E item = getSPI(spiType);

        if (item != null) {

                Collection<E> c = Collections.singletonList(item);

                return c;

        }

        return Collections.emptySet();

    }

}