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Commons Modeler example source code file (MbeansSource.java)

This example Commons Modeler source code file (MbeansSource.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Modeler tags/keywords

argsinfo, arraylist, dom, error, exception, exception, io, list, management, mlet, net, network, node, node, object, object, objectname, string, string, util

The Commons Modeler MbeansSource.java source code

/*
 * 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.commons.modeler.modules;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import javax.management.Attribute;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import javax.management.loading.MLet;
import javax.xml.transform.TransformerException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.modeler.AttributeInfo;
import org.apache.commons.modeler.BaseModelMBean;
import org.apache.commons.modeler.ManagedBean;
import org.apache.commons.modeler.Registry;
import org.apache.commons.modeler.util.DomUtil;
import org.w3c.dom.Document;
import org.w3c.dom.Node;


/** This will create mbeans based on a config file.
 *  The format is an extended version of MLET.
 *
 * Classloading. We don't support any explicit classloader tag. 
 * A ClassLoader is just an mbean ( it can be the standard MLetMBean or
 * a custom one ). 
 * 
 * XXX add a special attribute to reference the loader mbean,
 * XXX figure out how to deal with private loaders
 */
public class MbeansSource extends ModelerSource implements MbeansSourceMBean
{
    private static Log log = LogFactory.getLog(MbeansSource.class);
    Registry registry;
    String type;

    // true if we are during the original loading
    boolean loading=true;
    List mbeans=new ArrayList();
    static boolean loaderLoaded=false;
    private Document document;
    private HashMap object2Node = new HashMap();

    long lastUpdate;
    long updateInterval=10000; // 10s

    public void setRegistry(Registry reg) {
        this.registry=reg;
    }          

    public void setLocation( String loc ) {
        this.location=loc;
    }

    /** Used if a single component is loaded
     *
     * @param type
     */
    public void setType( String type ) {
       this.type=type;
    }

    public void setSource( Object source ) {
        this.source=source;
    }

    public Object getSource() {
        return source;
    }

    public String getLocation() {
        return location;
    }
    
    /** Return the list of mbeans created by this source.
     *  It can be used to implement runtime services.
     */
    public List getMBeans() {
        return mbeans;
    }

    public List loadDescriptors( Registry registry, String location,
                                 String type, Object source)
            throws Exception
    {
        setRegistry(registry);
        setLocation(location);
        setType(type);
        setSource(source);
        execute();
        return mbeans;
    }
    
    public void start() throws Exception {
        registry.invoke(mbeans, "start", false);        
    }

    public void stop() throws Exception {
        registry.invoke(mbeans, "stop", false);        
    }
    
    public void init() throws Exception {
        if( mbeans==null) execute();
        if( registry==null ) registry=Registry.getRegistry();
        
        registry.invoke(mbeans, "init", false);
    }
    
    public void destroy() throws Exception {
        registry.invoke(mbeans, "destroy", false);                
    }
    
    public void load() throws Exception {
        execute(); // backward compat
    }

    public void execute() throws Exception {
        if( registry==null ) registry=Registry.getRegistry();
        try {
            InputStream stream=getInputStream();
            long t1=System.currentTimeMillis();
            document = DomUtil.readXml(stream);

            // We don't care what the root node is.
            Node descriptorsN=document.getDocumentElement();

            if( descriptorsN == null ) {
                log.error("No descriptors found");
                return;
            }

            Node firstMbeanN=DomUtil.getChild(descriptorsN, null);

            if( firstMbeanN==null ) {
                // maybe we have a single mlet
                if( log.isDebugEnabled() )
                    log.debug("No child " + descriptorsN);
                firstMbeanN=descriptorsN;
            }

            MBeanServer server=(MBeanServer)Registry.getServer();

            // XXX Not very clean...  Just a workaround
            if( ! loaderLoaded ) {
                // Register a loader that will be find ant classes.
                ObjectName defaultLoader= new ObjectName("modeler",
                        "loader", "modeler");
                MLet mlet=new MLet( new URL[0], this.getClass().getClassLoader());
                server.registerMBean(mlet, defaultLoader);
                loaderLoaded=true;
            }
        
            // Process nodes
            for (Node mbeanN = firstMbeanN; mbeanN != null;
                 mbeanN= DomUtil.getNext(mbeanN, null, Node.ELEMENT_NODE))
            {
                String nodeName=mbeanN.getNodeName();

                // mbean is the "official" name
                if( "mbean".equals(nodeName) || "MLET".equals(nodeName) )
                {
                    String code=DomUtil.getAttribute( mbeanN, "code" );
                    String objectName=DomUtil.getAttribute( mbeanN, "objectName" );
                    if( objectName==null ) {
                        objectName=DomUtil.getAttribute( mbeanN, "name" );
                    }
                    
                    if( log.isDebugEnabled())
                        log.debug( "Processing mbean objectName=" + objectName +
                                " code=" + code);

                    // args can be grouped in constructor or direct childs
                    Node constructorN=DomUtil.getChild(mbeanN, "constructor");
                    if( constructorN == null ) constructorN=mbeanN;

                    ArgsInfo info = processArg(constructorN);

                    try {
                        ObjectName oname=new ObjectName(objectName);
                        if( ! server.isRegistered( oname )) {
                            // We wrap everything in a model mbean.
                            // XXX need to support "StandardMBeanDescriptorsSource"
                            String modelMBean=BaseModelMBean.class.getName();                            
                            if(info == null) {
                                server.createMBean(modelMBean, oname,
                                                   new Object[] { code, this},
                                                   new String[] { String.class.getName(),
                                                                  ModelerSource.class.getName() } 
                                                   );
                            } else {
                                server.createMBean(modelMBean, oname,
                                                   new Object[] { code, this,
                                                                  info.getValues(),
                                                                  info.getSigs()
                                                   },
                                                   new String[] { String.class.getName(),
                                                                  ModelerSource.class.getName(),
                                                                  Object[].class.getName(),
                                                                  String[].class.getName()
                                                   }
                                                   );
                            }
                                                   
                            mbeans.add(oname);
                        }
                        object2Node.put( oname, mbeanN );
                        // XXX Arguments, loader !!!
                    } catch( Exception ex ) {
                        log.error( "Error creating mbean " + objectName, ex);
                    }

                    Node firstAttN=DomUtil.getChild(mbeanN, "attribute");
                    for (Node descN = firstAttN; descN != null;
                         descN = DomUtil.getNext( descN ))
                    {
                        processAttribute(server, descN, objectName);
                    }
                } else if("jmx-operation".equals(nodeName) ) {
                    String name=DomUtil.getAttribute(mbeanN, "objectName");
                    if( name==null )
                        name=DomUtil.getAttribute(mbeanN, "name");

                    String operation=DomUtil.getAttribute(mbeanN, "operation");

                    if( log.isDebugEnabled())
                        log.debug( "Processing invoke objectName=" + name +
                                " code=" + operation);
                    try {
                        ObjectName oname=new ObjectName(name);

                        ArgsInfo info = processArg( mbeanN );
                        if(info == null) {
                            server.invoke( oname, operation, null, null);
                        } else {
                            server.invoke( oname, operation, info.getValues(), info.getSigs());
                        }
                    } catch (Exception e) {
                        log.error( "Error in invoke " + name + " " + operation);
                    }
                }

                ManagedBean managed=new ManagedBean();
                DomUtil.setAttributes(managed, mbeanN);
                Node firstN;

                // process attribute info
                firstN=DomUtil.getChild( mbeanN, "attribute");
                for (Node descN = firstN; descN != null;
                     descN = DomUtil.getNext( descN ))
                {
                    AttributeInfo ci=new AttributeInfo();
                    DomUtil.setAttributes(ci, descN);
                    managed.addAttribute( ci );
                }

            }

            long t2=System.currentTimeMillis();
            log.info( "Reading mbeans  " + (t2-t1));
            loading=false;
        } catch( Exception ex ) {
            log.error( "Error reading mbeans ", ex);
        }
    }
    
    public void updateField( ObjectName oname, String name, 
                             Object value )
    {
        if( loading ) return;
        // nothing by default
        //log.info( "XXX UpdateField " + oname + " " + name + " " + value);
        Node n=(Node)object2Node.get( oname );
        if( n == null ) {
            log.info( "Node not found " + oname );
            return;
        }
        Node attNode=DomUtil.findChildWithAtt(n, "attribute", "name", name);
        if( attNode == null ) {
            // found no existing attribute with this name
            attNode=n.getOwnerDocument().createElement("attribute");
            DomUtil.setAttribute(attNode, "name", name);
            n.appendChild(attNode);
        } 
        String oldValue=DomUtil.getAttribute(attNode, "value");
        if( oldValue != null ) {
            // we'll convert all values to text content
            DomUtil.removeAttribute( attNode, "value");
        }
        DomUtil.setText(attNode, value.toString());

        //store();
    }
    
    /** Store the mbeans. 
     * XXX add a background thread to store it periodically 
     */ 
    public void save() {
        // XXX customize no often than ( based on standard descriptor ), etc.
        // It doesn't work very well if we call this on each set att - 
        // the triger will work for the first att, but all others will be delayed
        long time=System.currentTimeMillis();
        if( location!=null &&
                time - lastUpdate > updateInterval ) {
            lastUpdate=time;
            try {
                FileOutputStream fos=new FileOutputStream(location);
                DomUtil.writeXml(document, fos);
            } catch (TransformerException e) {
                log.error( "Error writing");
            } catch (FileNotFoundException e) {
                log.error( "Error writing" ,e );
            }
        }
    }

    private void processAttribute(MBeanServer server,
                                  Node descN, String objectName ) {
        String attName=DomUtil.getAttribute(descN, "name");
        String value=DomUtil.getAttribute(descN, "value");
        String type=null; // DomUtil.getAttribute(descN, "type");
        if( value==null ) {
            // The value may be specified as CDATA
            value=DomUtil.getContent(descN);
        }
        try {
            if( log.isDebugEnabled())
                log.debug("Set attribute " + objectName + " " + attName +
                        " " + value);
            ObjectName oname=new ObjectName(objectName);
            // find the type
            if( type==null )
                type=registry.getType(  oname, attName );

            if( type==null ) {
                log.info("Can't find attribute " + objectName + " " + attName );

            } else {
                Object valueO=registry.convertValue( type, value);
                server.setAttribute(oname, new Attribute(attName, valueO));
            }
        } catch( Exception ex) {
            log.error("Error processing attribute " + objectName + " " +
                    attName + " " + value, ex);
        }

    }

    private ArgsInfo processArg(Node mbeanN) {
        Node firstArgN=DomUtil.getChild(mbeanN, "arg" );
        if(firstArgN == null) {
            return null;
        }
        ArgsInfo info = new ArgsInfo();
        // process all args
        for (Node argN = firstArgN; argN != null;
             argN = DomUtil.getNext( argN ))
        {
            String type=DomUtil.getAttribute(argN, "type");
            String value=DomUtil.getAttribute(argN, "value");
            if( value==null ) {
                // The value may be specified as CDATA
                value=DomUtil.getContent(argN);
            }
            info.addArgPair(type, registry.convertValue(type,value));
        }
        return info;
    }

    private static class ArgsInfo {
        private List sigs = new ArrayList();
        private List values = new ArrayList();

        ArgsInfo() {
        }

        public String [] getSigs() {
            return (String [])sigs.toArray(new String[sigs.size()]);
        }

        public Object[] getValues () {
            return values.toArray(new Object[values.size()]);
        }

        public void addArgPair(String name, Object val) {
            sigs.add(name);
            values.add(val);
        }
    }
}

Other Commons Modeler examples (source code examples)

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