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* Licensed to the Apache Software Foundation (ASF) under one
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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 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.Constants;
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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.rmi.RemoteException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* 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 {
// keep logger non-static so that it could be garbage collected with this
// instance.
protected final Logger logger;
protected ObjectContextFactory contextFactory;
protected String eventBridgeFactoryName;
protected Map<String, String> eventBridgeParameters;
/**
* @since 3.1
*/
public BaseRemoteService(ObjectContextFactory contextFactory, Map<String, String> eventBridgeProperties) {
logger = LoggerFactory.getLogger(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();
@Override
public RemoteSession establishSession() {
logger.debug("Session requested by client");
RemoteSession session = createServerSession().getSession();
logger.debug("Established client session: " + session);
return session;
}
@Override
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();
}
@Override
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);
}
}
@Override
public void close() throws RemoteException {
}
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(Constants.SERVER_ROP_EVENT_BRIDGE_FACTORY_PROPERTY);
if (eventBridgeFactoryName != null) {
Map<String, String> eventBridgeParameters = new HashMap<>(properties);
eventBridgeParameters.remove(Constants.SERVER_ROP_EVENT_BRIDGE_FACTORY_PROPERTY);
this.eventBridgeFactoryName = eventBridgeFactoryName;
this.eventBridgeParameters = eventBridgeParameters;
}
}
}