/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You 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.apache.catalina.ant.jmx;

import javax.management.MBeanServerConnection;

import javax.management.ObjectName;

import org.apache.tools.ant.BuildException;

/**

 * Access <em>JMX</em> JSR 160 MBeans Server. 

 * <ul>

 * <li>Get Mbeans attributes</li>

 * <li>Show Get result as Ant console log</li>

 * <li>Bind Get result as Ant properties</li>

 * </ul>

 * <p>

 * Examples:

 * <br/>

 * Get a Mbean IDataSender attribute nrOfRequests and create a new ant property <em>IDataSender.9025.nrOfRequests</em> 

 * <pre>

 *   <jmx:get

 *           ref="jmx.server"

 *           name="Catalina:type=IDataSender,host=localhost,senderAddress=192.168.1.2,senderPort=9025" 

 *           attribute="nrOfRequests"

 *           resultproperty="IDataSender.9025.nrOfRequests"

 *           echo="false">

 *       />

 * </pre>

 * </p>

 * <p>

 * First call to a remote MBeanserver save the JMXConnection a referenz <em>jmx.server</em>

 * </p>

 * These tasks require Ant 1.6 or later interface.

 *

 * @author Peter Rossbach

 * @since 5.5.10

 */

public class JMXAccessorGetTask extends JMXAccessorTask {

    // ----------------------------------------------------- Instance Variables

    private String attribute;

    // ----------------------------------------------------- Instance Info

    /**

     * Descriptive information describing this implementation.

     */

    private static final String info = "org.apache.catalina.ant.JMXAccessorGetTask/1.0";

    /**

     * Return descriptive information about this implementation and the

     * corresponding version number, in the format

     * <code>&lt;description&gt;/&lt;version&gt;</code>.

     */

    public String getInfo() {

        return (info);

    }

    // ------------------------------------------------------------- Properties

    /**

     * @return Returns the attribute.

     */

    public String getAttribute() {

        return attribute;

    }

    /**

     * @param attribute The attribute to set.

     */

    public void setAttribute(String attribute) {

        this.attribute = attribute;

    }

    // ------------------------------------------------------ protected Methods

    /**

     * Execute the specified command, based on the configured properties. The

     * input stream will be closed upon completion of this task, whether it was

     * executed successfully or not.

     * 

     * @exception BuildException

     *                if an error occurs

     */

    public String jmxExecute(MBeanServerConnection jmxServerConnection)

        throws Exception {

        if (getName() == null) {

            throw new BuildException("Must specify a 'name'");

        }

        if ((attribute == null)) {

            throw new BuildException(

                    "Must specify a 'attribute' for get");

        }

        return  jmxGet(jmxServerConnection, getName());

     }

    /**

     * @param jmxServerConnection

     * @param name

     * @return The value of the given named attribute

     * @throws Exception

     */

    protected String jmxGet(MBeanServerConnection jmxServerConnection,String name) throws Exception {

        String error = null;

        if(isEcho()) {

            handleOutput("MBean " + name + " get attribute " + attribute );

        }

        Object result = jmxServerConnection.getAttribute(

                new ObjectName(name), attribute);

        if (result != null) {

            echoResult(attribute,result);

            createProperty(result);

        } else

            error = "Attribute " + attribute + " is empty";

        return error;

    }

}