restsession.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: RestSession.java,v 1.11 2005/05/17 16:40:15 jmettraux Exp $
 */

//
// RestSession.java
//
// [e-mail]
//
// generated with 
// jtmpl 1.0.04 31.10.2002 John Mettraux ([e-mail])
//

package openwfe.org.rest;

import java.nio.channels.SelectionKey;

import openwfe.org.Utils;
import openwfe.org.ExceptionUtils;
import openwfe.org.ServiceException;
import openwfe.org.OpenWfeException;
import openwfe.org.ApplicationContext;
import openwfe.org.net.NetUtils;


/**
 * The skeleton of a REST session, implement it to handle your REST actions.
 *
 * <p><font size=2>CVS Info :
 * <br>$Author: jmettraux $
 * <br>$Date: 2005/05/17 16:40:15 $
 * <br>$Id: RestSession.java,v 1.11 2005/05/17 16:40:15 jmettraux Exp $ </font>
 *
 * @author [e-mail]
 */
public abstract class RestSession
{

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

    //
    // CONSTANTS and DEFINITIONS

    public final static String ACTION_END_WORK_SESSION
        = "endworksession";

    //
    // FIELDS

    protected RestService service = null;
    protected ApplicationContext applicationContext = null;
    protected java.util.Map serviceParams = null;
    protected Long sessionId = null;
    protected long lastUsed = -1;

    //
    // CONSTRUCTORS

    public void init 
        (final RestService service,
         final Long sessionId, 
         final String username,
         final String password)
    throws
        ServiceException
    {
        this.service = service;
        this.sessionId = sessionId;

        touch();

        authentify(username, password);
    }

    //
    // ABSTRACT METHODS

    /**
     * Implement this method so that it sets up the RMI or whatever
     * back session.
     */
    protected abstract boolean authentify 
        (String userName, String password)
    throws 
        ServiceException;

    /**
     * Implement for determining what to do with every REST action
     */
    protected boolean evalRequest 
        (final String action, 
         final SelectionKey key, 
         final String firstLine, 
         final byte[] request)
    throws
        Exception
    {
        final String methodName = "do_"+action.toLowerCase();

        final java.lang.reflect.Method method = this.getClass()
            .getMethod
                (methodName,
                 new Class[] 
                 { 
                     SelectionKey.class, 
                     String.class, 
                     byte[].class 
                 });

        final Object result = method.invoke
            (this, new Object[] { key, firstLine, request });

        if (result == null) return true;

        return ((Boolean)result).booleanValue();
    }

    //
    // METHODS

    public long getLastUsed ()
    {
        return this.lastUsed;
    }

    /**
     * Handles the incoming REST request
     */
    public void handle (final SelectionKey key, final byte[] request)
    {
        touch();

        //
        // which action is requested ?
        
        String firstLine = null;
        String action = null;
        Exception exception = null;
        try
        {
            firstLine = RestService.createBufferedReader(request)
                .readLine(); 

            action = RestUtils.extractFromLine(firstLine, "action");
        }
        catch (java.io.IOException ie)
        {
            log.info("Failed to parse 'action' from http request", ie);
            exception = ie;
        }

        if (action == null)
        {
            Object body = exception;
            if (body == null) body = "No specific action requested";
            
            NetUtils.httpReply
                (key,
                 400,
                 "Bad Request",
                 this.service.getServerName(),
                 null,
                 "text/plain",
                 body);
            return;
        }

        action = action.toLowerCase();

        //
        // point to action handling
        
        if (action.equals(ACTION_END_WORK_SESSION))
        {
            if (this.service != null)
                this.service.removeSession(this.sessionId);
            
            log.info("Session "+this.sessionId+" ended.");

            NetUtils.httpReply
                (key,
                 200,
                 "OK",
                 this.service.getServerName(),
                 null,
                 "text/xml",
                 new org.jdom.Element("bye"));
            return;
        }

        try
        {
            try
            {
                if (evalRequest(action, key, firstLine, request)) return;
            }
            catch (final java.lang.reflect.InvocationTargetException ite)
            {
                throw ite.getCause();
            }
        }
        catch (final java.net.MalformedURLException mue)
        {
            log.info("Malformed URL Exception : ", mue);

            NetUtils.httpReply
                (key,
                 400,
                 "Bad Request",
                 this.service.getServerName(),
                 null,
                 "text/plain",
                 mue);
            return;
        }
        catch (final HttpException he)
        {
            log.info("HTTP error : ", he);

            NetUtils.httpReply
                (key,
                 he.getErrorCode(),
                 he.getMessage(),
                 this.service.getServerName(),
                 null,
                 "text/plain",
                 he);
            return;
        }
        catch (final Throwable t)
        {
            log.info("Internal Server error : ", t);

            final Throwable rootCause = ExceptionUtils.getRootCause(t);

            NetUtils.httpReply
                (key,
                 500,
                 rootCause.toString()+" : "+rootCause.getMessage(),
                 this.service.getServerName(),
                 null,
                 "text/plain",
                 t);
            return;
        }

        NetUtils.httpReply
            (key,
             400,
             "Bad Request",
                 this.service.getServerName(),
             null,
             "text/plain",
             "Action '"+action+"' has no implementation.");
    }

    /**
     * This method simply updates the lastUsed field.
     */
    public void touch ()
    {
        this.lastUsed = System.currentTimeMillis();
    }

    protected void reply 
        (final SelectionKey key, final org.jdom.Element elt)
    {
        NetUtils.httpReply
            (key,
             200,
             "OK",
             this.service.getServerName(),
             null,
             "text/xml",
             elt);

        //log.debug("reply() :\n"+elt);
    }

    //
    // STATIC METHODS

    public static String printSessions (final java.util.Map sessions)
    {
        StringBuffer sb = new StringBuffer();

        sb.append("\n[\n ");

        java.util.Iterator it = sessions.keySet().iterator();
        while (it.hasNext())
        {
            Long sessionId = (Long)it.next();
            RestSession session = (RestSession)sessions.get(sessionId);

            sb.append("    ");
            sb.append(sessionId);
            sb.append(" : ");
            sb.append(new java.util.Date(session.getLastUsed()));

            if (it.hasNext())
            {
                sb.append(",\n");
            }
        }

        sb.append("\n]\n");

        return sb.toString();
    }

    private static String determineEncoding (String request)
        throws OpenWfeException
    {
        int i = request.indexOf("\r\n\r\n");

        if (i < 0) throw new OpenWfeException("Double EOL not found.");

        request = request.substring(i+4);

        i = request.indexOf("encoding=\"");

        if (i < 1) return Utils.getEncoding();
            // returns OpenWFE defined encoding
        
        request = request.substring(i+10);
        i = request.indexOf("\"");

        return request.substring(0, i);
    }

    public static org.jdom.Element parseBody 
        (final SelectionKey key, final byte[] request)
    throws 
        Exception
    {
        // debug
        //Utils.dump("rest_", request);

        final String encoding = determineEncoding(new String(request));

        log.debug("parseBody() encoding is >"+encoding+"<");

        String sRequest = new String(request, encoding);

        // remove header
        int i = sRequest.indexOf("\r\n\r\n");

        if (i < 0) throw new OpenWfeException("Double EOL not found.");

        sRequest = sRequest.substring(i+4);

        // debug
        //Utils.dump("rest_2_", sRequest.getBytes("iso-8859-1"));

        // remove noise
        i = sRequest.lastIndexOf(">");
        sRequest = sRequest.substring(0, i+1) + "\n";

        //log.debug("parseBody() after : \n"+sRequest);

        java.io.InputStream is = new java.io.ByteArrayInputStream
            (sRequest.getBytes(encoding));

        org.jdom.input.SAXBuilder builder = new org.jdom.input.SAXBuilder();
        org.jdom.Document doc = builder.build(is);

        return doc.getRootElement();
    }

    /**
     * This method is used to turn a simple exception into an HttpError,
     * very useful in final implementations of this class.
     */
    public static void rethrowAsHttpException 
        (final int httpErrorCode, final Exception e)
    throws 
        HttpException
    {
        throw new HttpException(httpErrorCode, e.getMessage());
    }

}