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* 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
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package org.apache.cayenne.remote.service;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.DataChannel;
import org.apache.cayenne.access.ClientServerChannel;
import org.apache.cayenne.access.DataContext;
import org.apache.cayenne.configuration.ObjectContextFactory;
import org.apache.cayenne.remote.ClientMessage;
import org.apache.cayenne.remote.RemoteService;
import org.apache.cayenne.remote.RemoteSession;
import org.apache.cayenne.util.Util;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* A generic implementation of an RemoteService. Can be subclassed to work with different
* remoting mechanisms, such as Hessian or JAXRPC.
*
* @since 1.2
*/
public abstract class BaseRemoteService implements RemoteService {
public static final String EVENT_BRIDGE_FACTORY_PROPERTY = "cayenne.RemoteService.EventBridge.factory";
// keep logger non-static so that it could be garbage collected with this instance.
protected final Log logger;
protected ObjectContextFactory contextFactory;
protected String eventBridgeFactoryName;
protected Map<String, String> eventBridgeParameters;
/**
* @since 3.1
*/
public BaseRemoteService(ObjectContextFactory contextFactory,
Map<String, String> eventBridgeProperties) {
logger = LogFactory.getLog(getClass());
// start Cayenne service
logger.debug("ROP service is starting");
this.contextFactory = contextFactory;
initEventBridgeParameters(eventBridgeProperties);
logger.debug(getClass().getName() + " started");
}
public String getEventBridgeFactoryName() {
return eventBridgeFactoryName;
}
public Map<String, String> getEventBridgeParameters() {
return eventBridgeParameters != null ? Collections
.unmodifiableMap(eventBridgeParameters) : Collections.EMPTY_MAP;
}
/**
* Creates a new ServerSession with a dedicated DataChannel.
*/
protected abstract ServerSession createServerSession();
/**
* Creates a new ServerSession based on a shared DataChannel.
*
* @param name shared session name used to lookup a shared DataChannel.
*/
protected abstract ServerSession createServerSession(String name);
/**
* Returns a ServerSession object that represents Cayenne-related state associated
* with the current session. If ServerSession hasn't been previously saved, returns
* null.
*/
protected abstract ServerSession getServerSession();
public RemoteSession establishSession() {
logger.debug("Session requested by client");
RemoteSession session = createServerSession().getSession();
logger.debug("Established client session: " + session);
return session;
}
public RemoteSession establishSharedSession(String name) {
logger.debug("Shared session requested by client. Group name: " + name);
if (name == null) {
throw new CayenneRuntimeException("Invalid null shared session name");
}
return createServerSession(name).getSession();
}
public Object processMessage(ClientMessage message) throws Throwable {
if (message == null) {
throw new IllegalArgumentException("Null client message.");
}
ServerSession handler = getServerSession();
if (handler == null) {
throw new MissingSessionException("No session associated with request.");
}
logger.debug("processMessage, sessionId: " + handler.getSession().getSessionId());
// intercept and log exceptions
try {
return DispatchHelper.dispatch(handler.getChannel(), message);
}
catch (Throwable th) {
StringBuilder wrapperMessage = new StringBuilder();
wrapperMessage.append("Exception processing message ").append(
message.getClass().getName()).append(" of type ").append(message);
String wrapperMessageString = wrapperMessage.toString();
logger.info(wrapperMessageString, th);
// This exception will probably be propagated to the client.
// Recast the exception to a serializable form.
Exception cause = new Exception(Util
.unwindException(th)
.getLocalizedMessage());
throw new CayenneRuntimeException(wrapperMessageString, cause);
}
}
protected RemoteSession createRemoteSession(
String sessionId,
String name,
boolean enableEvents) {
RemoteSession session = (enableEvents) ? new RemoteSession(
sessionId,
eventBridgeFactoryName,
eventBridgeParameters) : new RemoteSession(sessionId);
session.setName(name);
return session;
}
/**
* Creates a server-side channel that will handle all client requests. For shared
* sessions the same channel instance is reused for the entire group of clients. For
* dedicated sessions, one channel per client is created.
* <p/>
* This implementation returns {@link ClientServerChannel} instance wrapping a
* DataContext. Subclasses may override the method to customize channel creation. For
* instance they may wrap channel in the custom interceptors to handle transactions or
* security.
*/
protected DataChannel createChannel() {
return new ClientServerChannel((DataContext) contextFactory.createContext());
}
/**
* Initializes EventBridge parameters for remote clients peer-to-peer communications.
*/
protected void initEventBridgeParameters(Map<String, String> properties) {
String eventBridgeFactoryName = properties
.get(BaseRemoteService.EVENT_BRIDGE_FACTORY_PROPERTY);
if (eventBridgeFactoryName != null) {
Map<String, String> eventBridgeParameters = new HashMap<String, String>(
properties);
eventBridgeParameters.remove(BaseRemoteService.EVENT_BRIDGE_FACTORY_PROPERTY);
this.eventBridgeFactoryName = eventBridgeFactoryName;
this.eventBridgeParameters = eventBridgeParameters;
}
}
}