1 files changed, 247 insertions, 0 deletions
diff --git a/tags/java/sca/1.5.1-RC4/modules/binding-dwr/src/main/java/org/apache/tuscany/sca/binding/dwr/DWRServlet.java b/tags/java/sca/1.5.1-RC4/modules/binding-dwr/src/main/java/org/apache/tuscany/sca/binding/dwr/DWRServlet.java
new file mode 100644
index 0000000000..3a2471d8f3
--- /dev/null
+++ b/tags/java/sca/1.5.1-RC4/modules/binding-dwr/src/main/java/org/apache/tuscany/sca/binding/dwr/DWRServlet.java
@@ -0,0 +1,247 @@
+/*
+ * 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"  
+ *
+ * @version $Rev$ $Date$
+ */
+public class DWRServlet extends DwrServlet {
+    private static final long serialVersionUID = 1L;
+
+    private transient Map<String, ServiceHolder> services;
+    private transient List<String> referenceNames;
+    private transient boolean initialized;
+    private transient 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;
+    }
+
+}