/*
* Copyright 2011 Jeanfrancois Arcand
*
* Licensed 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.atmosphere.gwt.poll;
import com.google.gwt.user.client.rpc.IncompatibleRemoteServiceException;
import com.google.gwt.user.client.rpc.SerializationException;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.text.ParseException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet;
import com.google.gwt.user.server.rpc.RPC;
import com.google.gwt.user.server.rpc.RPCRequest;
import com.google.gwt.user.server.rpc.RPCServletUtils;
import com.google.gwt.user.server.rpc.SerializationPolicy;
import com.google.gwt.user.server.rpc.SerializationPolicyLoader;
import com.google.gwt.user.server.rpc.SerializationPolicyProvider;
import com.google.gwt.user.server.rpc.UnexpectedException;
import javax.servlet.ServletContext;
import org.atmosphere.cpr.AtmosphereResource;
import org.atmosphere.cpr.AtmosphereServlet;
import org.atmosphere.cpr.Broadcaster;
import org.atmosphere.cpr.BroadcasterFactory;
import org.atmosphere.cpr.DefaultBroadcaster;
public class AtmospherePollService extends AbstractRemoteServiceServlet
implements SerializationPolicyProvider {
public final static String GWT_SUSPENDED = "GWT_SUSPENDED";
public final static String GWT_REQUEST = "GWT_REQUEST";
public class SuspendInfo {
private AtmosphereResource<HttpServletRequest, HttpServletResponse> atm;
SuspendInfo(AtmosphereResource atm) {
this.atm = atm;
}
public void writeAndResume(Object message) throws IOException {
try {
AtmospherePollService.writeResponse(atm, message);
} finally {
atm.getRequest().removeAttribute(GWT_SUSPENDED);
atm.resume();
}
}
public Broadcaster getBroadcaster() {
return atm.getBroadcaster();
}
public Broadcaster createBroadcaster(String ID) {
try {
Broadcaster b = BroadcasterFactory.getDefault().get(DefaultBroadcaster.class, ID);
atm.setBroadcaster(b);
return b;
} catch (IllegalAccessException e) {
} catch (InstantiationException e) {
}
return null;
}
}
protected SuspendInfo suspend() {
AtmosphereResource<HttpServletRequest, HttpServletResponse> atm = getAtmosphereResource();
if (atm == null) {
throw new UnexpectedException("Failed to find Atmosphere resource have you setup Atmosphere?", null);
}
atm.getRequest().setAttribute(GWT_SUSPENDED, true);
atm.suspend(-1, false);
return new SuspendInfo(atm);
}
protected SuspendInfo suspend(long timeout) {
AtmosphereResource<HttpServletRequest, HttpServletResponse> atm = getAtmosphereResource();
atm.getRequest().setAttribute(GWT_SUSPENDED, true);
atm.suspend(timeout, false);
return new SuspendInfo(atm);
}
protected boolean isSuspended() {
AtmosphereResource<HttpServletRequest, HttpServletResponse> atm = getAtmosphereResource();
if (atm == null) {
throw new UnexpectedException("Failed to find Atmosphere resource have you setup Atmosphere?", null);
}
Boolean var = (Boolean)atm.getRequest().getAttribute(GWT_SUSPENDED);
return Boolean.TRUE.equals(var);
}
static void writeResponse(AtmosphereResource<HttpServletRequest, HttpServletResponse> resource, Object message) throws IOException{
try {
RPCRequest rpcRequest = (RPCRequest) resource.getRequest().getAttribute(AtmospherePollService.GWT_REQUEST);
String response = encodeResponse(rpcRequest, message);
writeResponse(resource.getRequest(), resource.getResponse(),
resource.getAtmosphereConfig().getServletContext(),
response);
} catch (IncompatibleRemoteServiceException ex) {
try {
String error = RPC.encodeResponseForFailure(null, ex);
writeResponse(resource.getRequest(), resource.getResponse(),
resource.getAtmosphereConfig().getServletContext(),
error);
} catch (SerializationException ex2) {
throw new IOException(ex2);
}
} catch (SerializationException ex) {
throw new IOException(ex);
}
}
static String encodeResponse(RPCRequest rpcRequest, Object message) throws SerializationException {
if (rpcRequest == null) {
throw new NullPointerException("rpcRequest");
}
if (rpcRequest.getSerializationPolicy() == null) {
throw new NullPointerException("serializationPolicy");
}
String responsePayload;
responsePayload = RPC.encodeResponseForSuccess(rpcRequest.getMethod(), message,
rpcRequest.getSerializationPolicy(), rpcRequest.getFlags());
return responsePayload;
}
@Override
protected void onAfterRequestDeserialized(RPCRequest rpcRequest) {
getAtmosphereResource().getRequest().setAttribute(GWT_REQUEST, rpcRequest);
}
private AtmosphereResource<HttpServletRequest, HttpServletResponse> getAtmosphereResource() {
AtmosphereResource<HttpServletRequest, HttpServletResponse> atm =
(AtmosphereResource<HttpServletRequest, HttpServletResponse>)
getThreadLocalRequest().getAttribute(AtmosphereServlet.ATMOSPHERE_RESOURCE);
if (atm == null) {
throw new UnexpectedException("Failed to find Atmosphere resource have you setup Atmosphere?", null);
}
return atm;
}
/////////////////////////////////////////////////////////////////////
//////////// Customized methods of RemoteServiceServlet /////////////
/////////////////////////////////////////////////////////////////////
/**
* Standard HttpServlet method: handle the POST.
*
* This doPost method swallows ALL exceptions, logs them in the
* ServletContext, and returns a GENERIC_FAILURE_MSG response with status code
* 500.
*
* @throws ServletException
* @throws SerializationException
*/
@Override
public final void processPost(HttpServletRequest request,
HttpServletResponse response) throws IOException, ServletException,
SerializationException {
// Read the request fully.
//
String requestPayload = readContent(request);
// Let subclasses see the serialized request.
//
onBeforeRequestDeserialized(requestPayload);
// Invoke the core dispatching logic, which returns the serialized
// result.
//
String responsePayload = processCall(requestPayload);
if (!isSuspended()) {
// Let subclasses see the serialized response.
//
onAfterResponseSerialized(responsePayload);
// Write the response.
//
writeResponse(request, response, getServletContext(), responsePayload);
}
}
/**
* Determines whether the response to a given servlet request should or should
* not be GZIP compressed. This method is only called in cases where the
* requester accepts GZIP encoding.
* <p>
* This implementation currently returns <code>true</code> if the response
* string's estimated byte length is longer than 256 bytes. Subclasses can
* override this logic.
* </p>
*
* @param request the request being served
* @param response the response that will be written into
* @param responsePayload the payload that is about to be sent to the client
* @return <code>true</code> if responsePayload should be GZIP compressed,
* otherwise <code>false</code>.
*/
protected static boolean shouldCompressResponse(HttpServletRequest request,
HttpServletResponse response, String responsePayload) {
return RPCServletUtils.exceedsUncompressedContentLengthLimit(responsePayload);
}
protected static void writeResponse(HttpServletRequest request,
HttpServletResponse response, ServletContext context, String responsePayload) throws IOException {
boolean gzipEncode = RPCServletUtils.acceptsGzipEncoding(request)
&& shouldCompressResponse(request, response, responsePayload);
RPCServletUtils.writeResponse(context, response,
responsePayload, gzipEncode);
}
/////////////////////////////////////////////////////////////////////
///////////////// COPY OF RemoteServiceServlet //////////////////////
/////////////////////////////////////////////////////////////////////
/**
* Used by HybridServiceServlet.
*/
static SerializationPolicy loadSerializationPolicy(HttpServlet servlet,
HttpServletRequest request, String moduleBaseURL, String strongName) {
// The request can tell you the path of the web app relative to the
// container root.
String contextPath = request.getContextPath();
String modulePath = null;
if (moduleBaseURL != null) {
try {
modulePath = new URL(moduleBaseURL).getPath();
} catch (MalformedURLException ex) {
// log the information, we will default
servlet.log("Malformed moduleBaseURL: " + moduleBaseURL, ex);
}
}
SerializationPolicy serializationPolicy = null;
/*
* Check that the module path must be in the same web app as the servlet
* itself. If you need to implement a scheme different than this, override
* this method.
*/
if (modulePath == null || !modulePath.startsWith(contextPath)) {
String message = "ERROR: The module path requested, "
+ modulePath
+ ", is not in the same web application as this servlet, "
+ contextPath
+ ". Your module may not be properly configured or your client and server code maybe out of date.";
servlet.log(message, null);
} else {
// Strip off the context path from the module base URL. It should be a
// strict prefix.
String contextRelativePath = modulePath.substring(contextPath.length());
String serializationPolicyFilePath = SerializationPolicyLoader.getSerializationPolicyFileName(contextRelativePath
+ strongName);
// Open the RPC resource file and read its contents.
InputStream is = servlet.getServletContext().getResourceAsStream(
serializationPolicyFilePath);
try {
if (is != null) {
try {
serializationPolicy = SerializationPolicyLoader.loadFromStream(is,
null);
} catch (ParseException e) {
servlet.log("ERROR: Failed to parse the policy file '"
+ serializationPolicyFilePath + "'", e);
} catch (IOException e) {
servlet.log("ERROR: Could not read the policy file '"
+ serializationPolicyFilePath + "'", e);
}
} else {
String message = "ERROR: The serialization policy file '"
+ serializationPolicyFilePath
+ "' was not found; did you forget to include it in this deployment?";
servlet.log(message);
}
} finally {
if (is != null) {
try {
is.close();
} catch (IOException e) {
// Ignore this error
}
}
}
}
return serializationPolicy;
}
/**
* A cache of moduleBaseURL and serialization policy strong name to
* {@link SerializationPolicy}.
*/
private final Map<String, SerializationPolicy> serializationPolicyCache = new HashMap<String, SerializationPolicy>();
/**
* The default constructor.
*/
public AtmospherePollService() {
}
public final SerializationPolicy getSerializationPolicy(String moduleBaseURL,
String strongName) {
SerializationPolicy serializationPolicy = getCachedSerializationPolicy(
moduleBaseURL, strongName);
if (serializationPolicy != null) {
return serializationPolicy;
}
serializationPolicy = doGetSerializationPolicy(getThreadLocalRequest(),
moduleBaseURL, strongName);
if (serializationPolicy == null) {
// Failed to get the requested serialization policy; use the default
log(
"WARNING: Failed to get the SerializationPolicy '"
+ strongName
+ "' for module '"
+ moduleBaseURL
+ "'; a legacy, 1.3.3 compatible, serialization policy will be used. You may experience SerializationExceptions as a result.",
null);
serializationPolicy = RPC.getDefaultSerializationPolicy();
}
// This could cache null or an actual instance. Either way we will not
// attempt to lookup the policy again.
putCachedSerializationPolicy(moduleBaseURL, strongName, serializationPolicy);
return serializationPolicy;
}
/**
* Process a call originating from the given request. Uses the
* {@link RPC#invokeAndEncodeResponse(Object, java.lang.reflect.Method, Object[])}
* method to do the actual work.
* <p>
* Subclasses may optionally override this method to handle the payload in any
* way they desire (by routing the request to a framework component, for
* instance). The {@link HttpServletRequest} and {@link HttpServletResponse}
* can be accessed via the {@link #getThreadLocalRequest()} and
* {@link #getThreadLocalResponse()} methods.
* </p>
* This is public so that it can be unit tested easily without HTTP.
*
* @param payload the UTF-8 request payload
* @return a string which encodes either the method's return, a checked
* exception thrown by the method, or an
* {@link IncompatibleRemoteServiceException}
* @throws SerializationException if we cannot serialize the response
* @throws UnexpectedException if the invocation throws a checked exception
* that is not declared in the service method's signature
* @throws RuntimeException if the service method throws an unchecked
* exception (the exception will be the one thrown by the service)
*/
public String processCall(String payload) throws SerializationException {
try {
RPCRequest rpcRequest = RPC.decodeRequest(payload, this.getClass(), this);
onAfterRequestDeserialized(rpcRequest);
return RPC.invokeAndEncodeResponse(this, rpcRequest.getMethod(),
rpcRequest.getParameters(), rpcRequest.getSerializationPolicy(),
rpcRequest.getFlags());
} catch (IncompatibleRemoteServiceException ex) {
log(
"An IncompatibleRemoteServiceException was thrown while processing this call.",
ex);
return RPC.encodeResponseForFailure(null, ex);
}
}
/**
* Gets the {@link SerializationPolicy} for given module base URL and strong
* name if there is one.
*
* Override this method to provide a {@link SerializationPolicy} using an
* alternative approach.
*
* @param request the HTTP request being serviced
* @param moduleBaseURL as specified in the incoming payload
* @param strongName a strong name that uniquely identifies a serialization
* policy file
* @return a {@link SerializationPolicy} for the given module base URL and
* strong name, or <code>null</code> if there is none
*/
protected SerializationPolicy doGetSerializationPolicy(
HttpServletRequest request, String moduleBaseURL, String strongName) {
return loadSerializationPolicy(this, request, moduleBaseURL, strongName);
}
/**
* Override this method to examine the serialized response that will be
* returned to the client. The default implementation does nothing and need
* not be called by subclasses.
*
* @param serializedResponse
*/
protected void onAfterResponseSerialized(String serializedResponse) {
}
/**
* Override this method to examine the serialized version of the request
* payload before it is deserialized into objects. The default implementation
* does nothing and need not be called by subclasses.
*
* @param serializedRequest
*/
protected void onBeforeRequestDeserialized(String serializedRequest) {
}
private SerializationPolicy getCachedSerializationPolicy(
String moduleBaseURL, String strongName) {
synchronized (serializationPolicyCache) {
return serializationPolicyCache.get(moduleBaseURL + strongName);
}
}
private void putCachedSerializationPolicy(String moduleBaseURL,
String strongName, SerializationPolicy serializationPolicy) {
synchronized (serializationPolicyCache) {
serializationPolicyCache.put(moduleBaseURL + strongName,
serializationPolicy);
}
}
}