/*
* Copyright 2009 Google Inc.
*
* 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 com.google.gwt.user.server.rpc;
import com.google.gwt.rpc.server.ClientOracle;
import com.google.gwt.rpc.server.RpcServlet;
import com.google.gwt.user.client.rpc.IncompatibleRemoteServiceException;
import com.google.gwt.user.client.rpc.RpcTokenException;
import com.google.gwt.user.client.rpc.SerializationException;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.servlet.http.HttpServletRequest;
/**
* EXPERIMENTAL and subject to change. Do not use this in production code.
* <p>
* This RemoteServiceServlet provides support for both legacy and deRPC clients
* at the cost of additional runtime overhead and API complexity.
*/
public class HybridServiceServlet extends RpcServlet implements
SerializationPolicyProvider {
/**
* Records permutations for which {@link #getClientOracle()} should return
* <code>null</code>.
*/
private final Set<String> legacyPermutations = new HashSet<String>();
/**
* A cache of moduleBaseURL and serialization policy strong name to
* {@link SerializationPolicy}.
*/
private final Map<String, SerializationPolicy> serializationPolicyCache = new HashMap<String, SerializationPolicy>();
/**
* This method will return <code>null</code> instead of throwing an exception.
*/
@Override
public ClientOracle getClientOracle() {
String strongName = getPermutationStrongName();
if (legacyPermutations.contains(strongName)) {
return null;
}
try {
return super.getClientOracle();
} catch (SerializationException e) {
legacyPermutations.add(strongName);
return null;
}
}
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.");
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;
}
@Override
public void processCall(ClientOracle clientOracle, String payload,
OutputStream stream) throws SerializationException {
if (!Character.isDigit(payload.charAt(0))) {
// Picking up null returned from getClientOracle()
if (clientOracle == null) {
throw new SerializationException("No ClientOracle for permutation "
+ getPermutationStrongName());
}
super.processCall(clientOracle, payload, stream);
} else {
String toReturn = processCall(payload);
onAfterResponseSerialized(toReturn);
try {
stream.write(toReturn.getBytes("UTF-8"));
} catch (IOException e) {
throw new SerializationException("Unable to commit bytes", e);
}
}
}
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);
} catch (RpcTokenException tokenException) {
log("An RpcTokenException was thrown while processing this call.",
tokenException);
return RPC.encodeResponseForFailure(null, tokenException);
}
}
/**
* 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 RemoteServiceServlet.loadSerializationPolicy(this, request,
moduleBaseURL, strongName);
}
/**
* @param serializedResponse
*/
protected void onAfterResponseSerialized(String serializedResponse) {
}
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);
}
}
}