/*
* 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.tuscany.sca.binding.dwr;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.directwebremoting.Container;
import org.directwebremoting.create.AbstractCreator;
import org.directwebremoting.extend.CreatorManager;
import org.directwebremoting.extend.Handler;
import org.directwebremoting.extend.Remoter;
import org.directwebremoting.servlet.DwrServlet;
import org.directwebremoting.servlet.EngineHandler;
import org.directwebremoting.servlet.PathConstants;
import org.directwebremoting.servlet.UrlProcessor;
/**
* Tuscany customized DWR Servlet to implement support for the DWR binding
*
* Handles requests for SCA services and references that use <binding.dwr>,
* and also the HTTP GET for the Tuscany DWR system script "scaDomain.js"
*/
public class DWRServlet extends DwrServlet {
private static final long serialVersionUID = 1L;
transient private Map<String, ServiceHolder> services;
transient private List<String> referenceNames;
transient private boolean initialized;
transient private Map<String, String> initParams;
private static final String SCADOMAIN_SCRIPT_PATH = "/scaDomain.js";
public DWRServlet() {
this.services = new HashMap<String, ServiceHolder>();
this.referenceNames = new ArrayList<String>();
this.initParams = new HashMap<String, String>();
// maybe use <binding.dwr> attributes to define the init params
initParams.put("activeReverseAjaxEnabled", "true");
}
@Override
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
super.service(req, res);
}
/**
* Initialize the servlet
* There is a single instance of this servlet which is registered
* for multiple path mappings, but the init should only run once.
*/
@Override
public void init(ServletConfig servletConfig) throws ServletException {
if (!initialized) {
super.init(patchConfig(servletConfig));
addScriptHandler();
initServices();
initialized = true;
}
}
/**
* Add in the handler to process the http get for /sca/scaDomain.js
*
* This wrappers the DWR Engine handler which returns the DWR engine.js script,
* this wrappers that handler so as to add Tuscany specific header and footer code
* to the DWR engine.js to define the Tuscany SCADomain control functions and
* functions for each SCA service and reference that use <binding.dwr>.
*/
private void addScriptHandler() {
UrlProcessor urlProcessor = (UrlProcessor)getContainer().getBean(UrlProcessor.class.getName());
final EngineHandler engineHandler =
(EngineHandler)getContainer().getBean(PathConstants.URL_PREFIX + "/engine.js");
final Handler scaDomainScriptHandler = new Handler() {
public void handle(HttpServletRequest request, HttpServletResponse response) throws IOException {
PrintWriter out = response.getWriter();
out.println("/** Apache Tuscany scaDomain.js Header */");
engineHandler.handle(request, response);
tuscanyFooter(request, out);
}
};
// add the scaDomainScriptHandler to the urlProcessor
// bit of a hack, there's probably cleaner way to get it registered
urlProcessor.afterContainerSetup(new Container() {
public Object getBean(String name) {
return scaDomainScriptHandler;
}
public Collection getBeanNames() {
return Arrays.asList(new String[] {PathConstants.URL_PREFIX + SCADOMAIN_SCRIPT_PATH});
}
});
}
/**
* Adds the JavaScript defining SCADomain, its control functions,
* and functions for all the available SCA services and references.
*/
private void tuscanyFooter(HttpServletRequest request, PrintWriter out) {
out.println("/** Apache Tuscany scaDomain.js Footer */");
out.println();
out.println("function scaDomain() { }");
out.println();
out.println("// SCA services");
// Use the DWR remoter to generate the JavaScipt function for each SCA service
Remoter remoter = (Remoter)getContainer().getBean(Remoter.class.getName());
String path = request.getContextPath() + request.getServletPath();
for (String serviceName : services.keySet()) {
String serviceScript = remoter.generateInterfaceScript(serviceName, path);
out.println(serviceScript);
}
if (referenceNames.size() > 0) {
out.println("// SCA reverse ajax control functions");
out.println();
out.println("scaDomain.open = function() { dwr.engine.setActiveReverseAjax(true); };");
out.println("scaDomain.close = function() { dwr.engine.setActiveReverseAjax(false); };");
out.println();
out.println("// SCA references");
out.println();
// the JavaScript function for SCA references has an
// empty impl as it uses DWR severside "push"
for (String referenceName : referenceNames) {
out.println("function " + referenceName + "() { }");
}
}
out.println();
out.println("/** End of Apache Tuscany scaDomain.js */");
out.println();
}
/**
* Add an SCA reference to be added to the DWR runtime
*/
public void addReference(String name) {
referenceNames.add(name);
}
/**
* Add an SCA service to be added to the DWR runtime
*/
public void addService(String name, final Class type, final Object instance) {
ServiceHolder holder = new ServiceHolder();
holder.name = name;
holder.type = type;
holder.instance = instance;
services.put(name, holder);
}
/**
* Defines each SCA service proxy instance to DWR
*/
private void initServices() {
CreatorManager creatorManager = (CreatorManager)getContainer().getBean(CreatorManager.class.getName());
for (final ServiceHolder holder : services.values()) {
creatorManager.addCreator(holder.name, new AbstractCreator() {
public Class getType() {
return holder.type;
}
public Object getInstance() throws InstantiationException {
return holder.instance;
}
});
}
}
// utility class to aid passing around services
private class ServiceHolder {
String name;
Class type;
Object instance;
}
/**
* Patch the ServletConfig to enable setting init params for DWR
* and so DWR can't see the Tuscany servlet's init params.
*/
private ServletConfig patchConfig(final ServletConfig servletConfig) {
ServletConfig patchedContext = new ServletConfig() {
public String getInitParameter(String name) {
return initParams.get(name);
}
public Enumeration getInitParameterNames() {
return Collections.enumeration(initParams.keySet());
}
public ServletContext getServletContext() {
return servletConfig.getServletContext();
}
public String getServletName() {
return servletConfig.getServletName();
}
};
return patchedContext;
}
}