xmlapplicationcontextbuilder.java

一个工作流设计及定义的系统,可以直接与数据库结合进行系统工作流程的定义及应用.

/*
 * Copyright (c) 2005, John Mettraux, OpenWFE.org
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 * . Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.  
 * 
 * . Redistributions in binary form must reproduce the above copyright notice, 
 *   this list of conditions and the following disclaimer in the documentation 
 *   and/or other materials provided with the distribution.
 * 
 * . Neither the name of the "OpenWFE" nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * $Id: XmlApplicationContextBuilder.java,v 1.5 2005/05/17 16:40:13 jmettraux Exp $
 */

//
// XmlApplicationContextBuilder.java
//
// [e-mail]
//
// generated with 
// jtmpl 1.1.01 2004/05/19 ([e-mail])
//

package openwfe.org.app;

import openwfe.org.Utils;
import openwfe.org.Service;
import openwfe.org.Parameters;
import openwfe.org.ApplicationContext;


/**
 * The classical decoder for OpenWFE application configuration files
 * (like etc/engine/engine-configuration.xml).
 *
 * <p><font size=2>CVS Info :
 * <br>$Author: jmettraux $
 * <br>$Id: XmlApplicationContextBuilder.java,v 1.5 2005/05/17 16:40:13 jmettraux Exp $ </font>
 *
 * @author [e-mail]
 */
public class XmlApplicationContextBuilder

    implements ApplicationContextBuilder

{

    private final static org.apache.log4j.Logger log = org.apache.log4j.Logger
        .getLogger(XmlApplicationContextBuilder.class.getName());

    //
    // CONSTANTS & co

    //
    // FIELDS

    //
    // CONSTRUCTORS

    /**
     * The Application will use this no-params constructor to get a fresh 
     * builder
     */
    public XmlApplicationContextBuilder ()
    {
        super();
    }

    //
    // METHODS from ApplicationContextBuilder

    public ApplicationContext build (final Object info)
        throws ApplicationBuildingException
    {
        if (info == null)
        {
            throw new ApplicationBuildingException
                ("Cannot build ApplicationContext out of 'null' info.");
        }

        if (info instanceof String)
        {
            final String s = (String)info;
            try
            {
                return build(new java.net.URL(Utils.expandUrl(s)));
            }
            catch (final java.net.MalformedURLException mue)
            {
                throw new ApplicationBuildingException
                    ("Cannot build ApplicationContext out of URL '"+info+"'");
            }
        }
        else if (info instanceof java.net.URL)
        {
            return doBuild((java.net.URL)info);
        }

        throw new ApplicationBuildingException
            ("Cannot build ApplicationContext out of instance of class "+
             info.getClass());
    }

    //
    // METHODS

    private ApplicationContext doBuild (final java.net.URL url)
        throws ApplicationBuildingException
    {
        log.info("doBuild(u) building from '"+url+"'");

        org.jdom.Document xmlConfiguration = null;
        try
        {
            org.jdom.input.SAXBuilder builder = new org.jdom.input.SAXBuilder();

            xmlConfiguration = builder.build(url);
        }
        catch (Exception e)
        {
            throw new ApplicationBuildingException
                ("Failed to interpret configuration file '"+url+"'", e);
        }

        return doBuild(xmlConfiguration.getRootElement());
    }

    private ApplicationContext doBuild (final org.jdom.Element element)
        throws ApplicationBuildingException
    {
        ApplicationContext result = new ApplicationContext();

        //
        // if there is a name to the rootElement,
        // then store the resultingApplication context is the singleton map...
        
        String name = element.getAttributeValue("name");

        if (name != null)
        {
            name = name.trim();
            result.setApplicationName(name);
            ApplicationContext.contextMap.put(name, result);
        }

        //
        // include child configurations
        
        java.util.Iterator it = element.getChildren("include").iterator();
        while (it.hasNext())
        {
            final org.jdom.Element eInclude = (org.jdom.Element)it.next();
            final String configFileName = 
                eInclude.getAttributeValue("configuration");

            final ApplicationContext child = build(configFileName);

            child.setParentContext(result);

            result.put(child.getApplicationName(), child);

            log.info
                ("Added sub-application under '"+
                 child.getApplicationName()+"'");
        }

        //
        // extract global parameters
        
        java.util.Map globalParams = Parameters.extractParameters(element);

        result.putAll(globalParams);

        //
        // extract and instantiate services
        
        java.util.List services = element.getChildren("service");

        it = services.iterator();
        while (it.hasNext())
        {
            org.jdom.Element elt = (org.jdom.Element)it.next();

            //
            // gather info

            String serviceName = elt.getAttributeValue("name");
            String serviceClassName = elt.getAttributeValue("class");

            java.util.Map serviceParams = Parameters.extractParameters(elt);

            //
            // instantiate service

            Service service = null;
            try
            {
                Class serviceClass = Class.forName(serviceClassName);
                service = (Service)serviceClass.newInstance();

                service.init(serviceName, result, serviceParams);
            }
            catch (Throwable t)
            {
                //throw new ServiceException
                log.info
                    ("Failed to instantiate service '"+serviceName+"'", t);
                continue;
            }

            // and bind it into context

            result.put(serviceName, service);

            //
            // service is ready.

            log.info
                ("bound service '"+serviceName+"' ("+serviceClassName+")");
        }

        log.info
            ("Application '"+name+"' has been launched\n\n");

        return result;
    }

    //
    // STATIC METHODS

}