framework/src/net/sf/tapestry/engine/AbstractService.java

/*
 *  ====================================================================
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2002 The Apache Software Foundation.  All rights
 *  reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. 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.
 *
 *  3. The end-user documentation included with the redistribution,
 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
 *  4. The names "Apache" and "Apache Software Foundation" and
 *  "Apache Tapestry" must not be used to endorse or promote products
 *  derived from this software without prior written permission. For
 *  written permission, please contact apache@apache.org.
 *
 *  5. Products derived from this software may not be called "Apache",
 *  "Apache Tapestry", nor may "Apache" appear in their name, without
 *  prior written permission of the Apache Software Foundation.
 *
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 *  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.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of the Apache Software Foundation.  For more
 *  information on the Apache Software Foundation, please see
 *  <http://www.apache.org/>.
 */
package net.sf.tapestry.engine;

import java.io.IOException;

import net.sf.tapestry.ApplicationRuntimeException;
import net.sf.tapestry.Gesture;
import net.sf.tapestry.IEngineService;
import net.sf.tapestry.IRequestCycle;
import net.sf.tapestry.RequestContext;
import net.sf.tapestry.Tapestry;
import net.sf.tapestry.util.StringSplitter;
import net.sf.tapestry.util.io.DataSqueezer;

/**
 *  Abstract base class for implementing engine services.  Instances of services
 *  are shared by many engines and threads, so they must be threadsafe.
 * 
 *  <p>
 *  Note; too much of the URL encoding/decoding stategy is fixed here.
 *  A future release of Tapestry may extract this strategy, allowing developers
 *  to choose the method via which URLs are encoded.
 * 
 *  @see net.sf.tapestry.engine.AbstractEngine#getService(String)
 * 
 *
 *  @author Howard Lewis Ship
 *  @version $Id$
 *  @since 1.0.3
 * 
 **/

public abstract class AbstractService implements IEngineService
{
    /**
     *  Assembles a URL for the service.
     *
     *  @param the path for the servlet for this Tapestry application
     *  @param serviceName the name of the service
     *  @param serviceContext context related to the service itself which is added to the URL as-is
     *  @param otherContext additional context provided by the component; this is application specific
     *  information, and is encoded with {@link URLEncoder#encode(String)} before being added
     *  to the query.
     *  @param stateful if true, the final URL must be encoded with the HttpSession id
     *
     **/

    protected Gesture assembleGesture(
        IRequestCycle cycle,
        String serviceName,
        String[] serviceContext,
        Object[] parameters,
        boolean stateful)
    {
        DataSqueezer squeezer = cycle.getEngine().getDataSqueezer();
        String[] squeezed = null;

        try
        {
            squeezed = squeezer.squeeze(parameters);
        }
        catch (IOException ex)
        {
            throw new ApplicationRuntimeException(ex);
        }

        return new Gesture(cycle, serviceName, serviceContext, squeezed, stateful);
    }

    /**
     *  Returns the service context as an array of Strings.
     *  Returns null if there are no service context strings.
     *
     **/

    protected String[] getServiceContext(RequestContext context)
    {
        String raw = context.getParameter(CONTEXT_QUERY_PARMETER_NAME);
        
        if (raw == null)
            return null;
            
        return new StringSplitter('/').splitToArray(raw);
    }

    /**
     *  Returns the service parameters as an array of Strings.
     *
     **/

    protected Object[] getParameters(IRequestCycle cycle)
    {
        RequestContext context = cycle.getRequestContext();
        
        String[] squeezed = 
            context.getParameters(PARAMETERS_QUERY_PARAMETER_NAME);
            
        if (Tapestry.size(squeezed) == 0)
            return squeezed;
            
        try
        {
            DataSqueezer squeezer =
                cycle.getEngine().getDataSqueezer();
                
            return squeezer.unsqueeze(squeezed);
        }
        catch (IOException ex)
        {
            throw new ApplicationRuntimeException(ex);
        }
    }
}