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Cayenne Object Persistence Framework
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* 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.cayenne.remote.hessian;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.event.EventBridge;
import org.apache.cayenne.remote.BaseConnection;
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 com.caucho.hessian.client.HessianRuntimeException;
import com.caucho.hessian.io.HessianProtocolException;
/**
* An ClientConnection that passes messages to a remotely deployed HessianService. It
* supports HTTP BASIC authentication. HessianConnection serializes messages using Hessian
* binary web service protocol over HTTP. For more info on Hessian see Caucho site at http://www.caucho.com/resin-3.0/protocols/hessian.xtp.
* HessianConnection supports logging of message traffic via Jakarta commons-logging API.
*
* @since 1.2
* @author Andrus Adamchik
*/
public class HessianConnection extends BaseConnection {
public static final String[] CLIENT_SERIALIZER_FACTORIES = new String[] {
ClientSerializerFactory.class.getName(), EnumSerializerProxy.class.getName()
};
protected String url;
protected String userName;
protected String password;
protected String sharedSessionName;
protected RemoteSession session;
protected RemoteService service;
/**
* Creates HessianConnection that will establish dedicated session and will not use
* HTTP basic authentication.
*/
public HessianConnection(String url) {
this(url, null, null, null);
}
/**
* Creates a HessianConnection. This constructor can optionally setup basic
* authentication credentials and configure shared session. url
is the
* only required parameter.
*/
public HessianConnection(String url, String userName, String password,
String sharedSessionName) {
if (url == null) {
throw new IllegalArgumentException("URL of Cayenne service is null.");
}
this.url = url;
this.userName = userName;
this.password = password;
this.sharedSessionName = sharedSessionName;
}
/**
* Returns a URL of Cayenne service used by this connector.
*/
public String getUrl() {
return url;
}
/**
* Returns user name that is used for basic authentication when connecting to the
* cayenne server.
*/
public String getUserName() {
return userName;
}
/**
* Returns password that is used for basic authentication when connecting to the
* cayenne server.
*/
public String getPassword() {
return password;
}
public String getSharedSessionName() {
return sharedSessionName;
}
public EventBridge getServerEventBridge() throws CayenneRuntimeException {
if (session == null) {
connect();
}
return session.isServerEventsEnabled() ? session.createServerEventBridge() : null;
}
/**
* Retunrs internal RemoteSession instance.
*/
RemoteSession getSession() {
return session;
}
/**
* Establishes server session if needed.
*/
protected void beforeSendMessage(ClientMessage message)
throws CayenneRuntimeException {
// for now only support session-based communications...
if (session == null) {
connect();
}
}
/**
* Sends a message to remote Cayenne Hessian service.
*/
protected Object doSendMessage(ClientMessage message) throws CayenneRuntimeException {
try {
return service.processMessage(message);
}
catch (Throwable th) {
th = unwindThrowable(th);
String errorMessage = buildExceptionMessage("Remote error", th);
throw new CayenneRuntimeException(errorMessage, th);
}
}
/**
* Establishes a session with remote service.
*/
protected synchronized void connect() throws CayenneRuntimeException {
if (session != null) {
return;
}
long t0 = 0;
if (logger.isInfoEnabled()) {
t0 = System.currentTimeMillis();
StringBuffer log = new StringBuffer("Connecting to [");
if (userName != null) {
log.append(userName);
if (password != null) {
log.append(":*******");
}
log.append("@");
}
log.append(url);
log.append("]");
if (sharedSessionName != null) {
log.append(" - shared session '").append(sharedSessionName).append("'");
}
else {
log.append(" - dedicated session.");
}
logger.info(log.toString());
}
// init service proxy...
HessianProxyFactory factory = new HessianProxyFactory(this);
factory.setSerializerFactory(HessianConfig.createFactory(
CLIENT_SERIALIZER_FACTORIES,
null));
factory.setUser(userName);
factory.setPassword(password);
try {
this.service = (RemoteService) factory.create(RemoteService.class, url);
}
catch (Throwable th) {
th = unwindThrowable(th);
String message = buildExceptionMessage("URL error", th);
throw new CayenneRuntimeException(message, th);
}
// create server session...
try {
session = (sharedSessionName != null) ? service
.establishSharedSession(sharedSessionName) : service
.establishSession();
if (logger.isInfoEnabled()) {
long time = System.currentTimeMillis() - t0;
logger.info("=== Connected, session: "
+ session
+ " - took "
+ time
+ " ms.");
}
}
catch (Throwable th) {
th = unwindThrowable(th);
th.printStackTrace();
String message = buildExceptionMessage(
"Error establishing remote session",
th);
throw new CayenneRuntimeException(message, th);
}
// TODO: send a connect event...
}
String buildExceptionMessage(String message, Throwable th) {
StringBuffer buffer = new StringBuffer(message);
buffer.append(". URL - ").append(url);
String thMessage = th.getMessage();
if (!Util.isEmptyString(thMessage)) {
buffer.append("; CAUSE - ").append(thMessage);
}
return buffer.toString();
}
/**
* Utility method to get exception cause. Implements special handling of Hessian
* exceptions.
*/
Throwable unwindThrowable(Throwable th) {
if (th instanceof HessianProtocolException) {
Throwable cause = ((HessianProtocolException) th).getRootCause();
if (cause != null) {
return unwindThrowable(cause);
}
}
else if (th instanceof HessianRuntimeException) {
Throwable cause = ((HessianRuntimeException) th).getRootCause();
if (cause != null) {
return unwindThrowable(cause);
}
}
return Util.unwindException(th);
}
}
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