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package javax.management.remote;

import com.sun.jmx.remote.util.ClassLogger;

import com.sun.jmx.remote.util.EnvHelp;

import java.io.IOException;

import java.net.MalformedURLException;

import java.util.Collections;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

import javax.management.MBeanServer;

/**

 * <p>Factory to create JMX API connector servers.  There

 * are no instances of this class.</p>

 *

 * <p>Each connector server is created by an instance of {@link

 * JMXConnectorServerProvider}.  This instance is found as follows.  Suppose

 * the given {@link JMXServiceURL} looks like

 * <code>"service:jmx:<em>protocol</em>:<em>remainder</em>"</code>.

 * Then the factory will attempt to find the appropriate {@link

 * JMXConnectorServerProvider} for <code><em>protocol</em></code>.  Each

 * occurrence of the character <code>+</code> or <code>-</code> in

 * <code><em>protocol</em></code> is replaced by <code>.</code> or

 * <code>_</code>, respectively.</p>

 *

 * <p>A <em>provider package list</em> is searched for as follows:</p>

 *

 * <ol>

 *

 * <li>If the <code>environment</code> parameter to {@link

 * #newJMXConnectorServer(JMXServiceURL,Map,MBeanServer)

 * newJMXConnectorServer} contains the key

 * <code>jmx.remote.protocol.provider.pkgs</code> then the associated

 * value is the provider package list.

 *

 * <li>Otherwise, if the system property

 * <code>jmx.remote.protocol.provider.pkgs</code> exists, then its value

 * is the provider package list.

 *

 * <li>Otherwise, there is no provider package list.

 *

 * </ol>

 *

 * <p>The provider package list is a string that is interpreted as a

 * list of non-empty Java package names separated by vertical bars

 * (<code>|</code>).  If the string is empty, then so is the provider

 * package list.  If the provider package list is not a String, or if

 * it contains an element that is an empty string, a {@link

 * JMXProviderException} is thrown.</p>

 *

 * <p>If the provider package list exists and is not empty, then for

 * each element <code><em>pkg</em></code> of the list, the factory

 * will attempt to load the class

 *

 * <blockquote>

 * <code><em>pkg</em>.<em>protocol</em>.ServerProvider</code>

 * </blockquote>

 * <p>If the <code>environment</code> parameter to {@link

 * #newJMXConnectorServer(JMXServiceURL, Map, MBeanServer)

 * newJMXConnectorServer} contains the key

 * <code>jmx.remote.protocol.provider.class.loader</code> then the

 * associated value is the class loader to use to load the provider.

 * If the associated value is not an instance of {@link

 * java.lang.ClassLoader}, an {@link

 * java.lang.IllegalArgumentException} is thrown.</p>

 *

 * <p>If the <code>jmx.remote.protocol.provider.class.loader</code>

 * key is not present in the <code>environment</code> parameter, the

 * calling thread's context class loader is used.</p>

 *

 * <p>If the attempt to load this class produces a {@link

 * ClassNotFoundException}, the search for a handler continues with

 * the next element of the list.</p>

 *

 * <p>Otherwise, a problem with the provider found is signalled by a

 * {@link JMXProviderException} whose {@link

 * JMXProviderException#getCause() <em>cause</em>} indicates the

 * underlying exception, as follows:</p>

 *

 * <ul>

 *

 * <li>if the attempt to load the class produces an exception other

 * than <code>ClassNotFoundException</code>, that is the

 * <em>cause</em>;

 *

 * <li>if {@link Class#newInstance()} for the class produces an

 * exception, that is the <em>cause</em>.

 *

 * </ul>

 *

 * <p>If no provider is found by the above steps, including the

 * default case where there is no provider package list, then the

 * implementation will use its own provider for

 * <code><em>protocol</em></code>, or it will throw a

 * <code>MalformedURLException</code> if there is none.  An

 * implementation may choose to find providers by other means.  For

 * example, it may support the <a

 * JAR conventions for service providers</a>, where the service

 * interface is <code>JMXConnectorServerProvider</code>.</p>

 *

 * <p>Every implementation must support the RMI connector protocol with

 * the default RMI transport, specified with string <code>rmi</code>.

 * An implementation may optionally support the RMI connector protocol

 * with the RMI/IIOP transport, specified with the string

 * <code>iiop</code>.</p>

 *

 * <p>Once a provider is found, the result of the

 * <code>newJMXConnectorServer</code> method is the result of calling

 * {@link

 * JMXConnectorServerProvider#newJMXConnectorServer(JMXServiceURL,

 * Map, MBeanServer) newJMXConnectorServer} on the provider.</p>

 *

 * <p>The <code>Map</code> parameter passed to the

 * <code>JMXConnectorServerProvider</code> is a new read-only

 * <code>Map</code> that contains all the entries that were in the

 * <code>environment</code> parameter to {@link

 * #newJMXConnectorServer(JMXServiceURL,Map,MBeanServer)

 * JMXConnectorServerFactory.newJMXConnectorServer}, if there was one.

 * Additionally, if the

 * <code>jmx.remote.protocol.provider.class.loader</code> key is not

 * present in the <code>environment</code> parameter, it is added to

 * the new read-only <code>Map</code>. The associated value is the

 * calling thread's context class loader.</p>

 *

 * @since 1.5

 */

public class JMXConnectorServerFactory {

    /**

     * <p>Name of the attribute that specifies the default class

     * loader.  This class loader is used to deserialize objects in

     * requests received from the client, possibly after consulting an

     * MBean-specific class loader.  The value associated with this

     * attribute is an instance of {@link ClassLoader}.</p>

     */

    public static final String DEFAULT_CLASS_LOADER =

        JMXConnectorFactory.DEFAULT_CLASS_LOADER;

    /**

     * <p>Name of the attribute that specifies the default class

     * loader MBean name.  This class loader is used to deserialize objects in

     * requests received from the client, possibly after consulting an

     * MBean-specific class loader.  The value associated with this

     * attribute is an instance of {@link javax.management.ObjectName

     * ObjectName}.</p>

     */

    public static final String DEFAULT_CLASS_LOADER_NAME =

        "jmx.remote.default.class.loader.name";

    /**

     * <p>Name of the attribute that specifies the provider packages

     * that are consulted when looking for the handler for a protocol.

     * The value associated with this attribute is a string with

     * package names separated by vertical bars (<code>|</code>).</p>

     */

    public static final String PROTOCOL_PROVIDER_PACKAGES =

        "jmx.remote.protocol.provider.pkgs";

    /**

     * <p>Name of the attribute that specifies the class

     * loader for loading protocol providers.

     * The value associated with this attribute is an instance

     * of {@link ClassLoader}.</p>

     */

    public static final String PROTOCOL_PROVIDER_CLASS_LOADER =

        "jmx.remote.protocol.provider.class.loader";

    private static final String PROTOCOL_PROVIDER_DEFAULT_PACKAGE =

        "com.sun.jmx.remote.protocol";

    private static final ClassLogger logger =

        new ClassLogger("javax.management.remote.misc","JMXConnectorServerFactory");

    /** There are no instances of this class.  */

    private JMXConnectorServerFactory() {

    }

    private static JMXConnectorServer

        getConnectorServerAsService(ClassLoader loader,

                                    JMXServiceURL url,

                                    Map<String, ?> map,

                                    MBeanServer mbs)

        throws IOException {

        Iterator<JMXConnectorServerProvider> providers =

                JMXConnectorFactory.

                getProviderIterator(JMXConnectorServerProvider.class, loader);

        IOException exception = null;

        while (providers.hasNext()) {

            try {

                return providers.next().newJMXConnectorServer(url, map, mbs);

            } catch (JMXProviderException e) {

                throw e;

            } catch (Exception e) {

                if (logger.traceOn())

                    logger.trace("getConnectorAsService",

                                 "URL[" + url +

                                 "] Service provider exception: " + e);

                if (!(e instanceof MalformedURLException)) {

                    if (exception == null) {

                        if (e instanceof IOException) {

                            exception = (IOException) e;

                        } else {

                            exception = EnvHelp.initCause(

                                new IOException(e.getMessage()), e);

                        }

                    }

                }

                continue;

            }

        }

        if (exception == null)

            return null;

        else

            throw exception;

    }

    /**

     * <p>Creates a connector server at the given address.  The

     * resultant server is not started until its {@link

     * JMXConnectorServer#start() start} method is called.</p>

     *

     * @param serviceURL the address of the new connector server.  The

     * actual address of the new connector server, as returned by its

     * {@link JMXConnectorServer#getAddress() getAddress} method, will

     * not necessarily be exactly the same.  For example, it might

     * include a port number if the original address did not.

     *

     * @param environment a set of attributes to control the new

     * connector server's behavior.  This parameter can be null.

     * Keys in this map must be Strings.  The appropriate type of each

     * associated value depends on the attribute.  The contents of

     * <code>environment</code> are not changed by this call.

     *

     * @param mbeanServer the MBean server that this connector server

     * is attached to.  Null if this connector server will be attached

     * to an MBean server by being registered in it.

     *

     * @return a <code>JMXConnectorServer</code> representing the new

     * connector server.  Each successful call to this method produces

     * a different object.

     *

     * @exception NullPointerException if <code>serviceURL</code> is null.

     *

     * @exception IOException if the connector server cannot be made

     * because of a communication problem.

     *

     * @exception MalformedURLException if there is no provider for the

     * protocol in <code>serviceURL</code>.

     *

     * @exception JMXProviderException if there is a provider for the

     * protocol in <code>serviceURL</code> but it cannot be used for

     * some reason.

     */

    public static JMXConnectorServer

        newJMXConnectorServer(JMXServiceURL serviceURL,

                              Map<String,?> environment,

                              MBeanServer mbeanServer)

            throws IOException {

        Map<String, Object> envcopy;

        if (environment == null)

            envcopy = new HashMap<String, Object>();

        else {

            EnvHelp.checkAttributes(environment);

            envcopy = new HashMap<String, Object>(environment);

        }

        final Class<JMXConnectorServerProvider> targetInterface =

                JMXConnectorServerProvider.class;

        final ClassLoader loader =

            JMXConnectorFactory.resolveClassLoader(envcopy);

        final String protocol = serviceURL.getProtocol();

        final String providerClassName = "ServerProvider";

        JMXConnectorServerProvider provider =

            JMXConnectorFactory.getProvider(serviceURL,

                                            envcopy,

                                            providerClassName,

                                            targetInterface,

                                            loader);

        IOException exception = null;

        if (provider == null) {

            // Loader is null when context class loader is set to null

            // and no loader has been provided in map.

            // com.sun.jmx.remote.util.Service class extracted from j2se

            // provider search algorithm doesn't handle well null classloader.

            if (loader != null) {

                try {

                    JMXConnectorServer connection =

                        getConnectorServerAsService(loader,

                                                    serviceURL,

                                                    envcopy,

                                                    mbeanServer);

                    if (connection != null)

                        return connection;

                } catch (JMXProviderException e) {

                    throw e;

                } catch (IOException e) {

                    exception = e;

                }

            }

            provider =

                JMXConnectorFactory.getProvider(

                    protocol,

                    PROTOCOL_PROVIDER_DEFAULT_PACKAGE,

                    JMXConnectorFactory.class.getClassLoader(),

                    providerClassName,

                    targetInterface);

        }

        if (provider == null) {

            MalformedURLException e =

                new MalformedURLException("Unsupported protocol: " + protocol);

            if (exception == null) {

                throw e;

            } else {

                throw EnvHelp.initCause(e, exception);

            }

        }

        envcopy = Collections.unmodifiableMap(envcopy);

        return provider.newJMXConnectorServer(serviceURL,

                                              envcopy,

                                              mbeanServer);

    }

}