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JSR 356: Java API for WebSocket
There is a newer version: 1.1
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package javax.websocket.server;

import java.util.ServiceLoader;
import javax.websocket.Session;

/**
 * The ServerContainerProvider class allows the developer to obtain
 * a reference to the instance of the ServerContainer for containing application. 
 * This is intended for standalone implementations to bootstrap the 
 * ServerContainer, or for implementations in the web container to obtain a 
 * reference to the ServerContainer from within a Java servlet API ServletContextListener 
 * in order to do programmatic deployment. 
 * 
 * @author dannycoward
 */


public abstract class ServerContainerProvider {
 
    /**
     * Obtain a reference to the instance of the ServerContainer during
     * application deployment. Developers wishing to access the
     * ServerContainer instance from within an active endpoint should call
     * {@link Session#getContainer()} instead.
     * 
     * @return the ServerContainer instance
     * @throws IllegalStateException if called from within an active endpoint.
     */
    public static ServerContainer getServerContainer() {
        ServerContainer sc = null;
        for (ServerContainerProvider impl : ServiceLoader.load(ServerContainerProvider.class)) {
            sc = impl.getContainer();
            if (sc != null) {
                return sc;
            } 
        }
        if (sc == null) {
            throw new RuntimeException("Could not find an implementation class.");
        } else {
            throw new RuntimeException("Could not find an implementation class with a non-null ServerContainer.");
        }
    }
 
    /**
     * Load the server container implementation.
     * @throws IllegalStateException if called from within an active websocket endpoint.
     * @return the server container class
     * 
     */
    protected abstract ServerContainer getContainer();
}