/*
* Copyright 2002-2010 the original author or authors.
*
* 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.springframework.remoting.httpinvoker;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.remoting.rmi.RemoteInvocationSerializingExporter;
import org.springframework.remoting.support.RemoteInvocation;
import org.springframework.remoting.support.RemoteInvocationResult;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.util.NestedServletException;
/**
* Servlet-API-based HTTP request handler that exports the specified service bean
* as HTTP invoker service endpoint, accessible via an HTTP invoker proxy.
*
* <p><b>Note:</b> Spring also provides an alternative version of this exporter,
* for Sun's JRE 1.6 HTTP server: {@link SimpleHttpInvokerServiceExporter}.
*
* <p>Deserializes remote invocation objects and serializes remote invocation
* result objects. Uses Java serialization just like RMI, but provides the
* same ease of setup as Caucho's HTTP-based Hessian and Burlap protocols.
*
* <p><b>HTTP invoker is the recommended protocol for Java-to-Java remoting.</b>
* It is more powerful and more extensible than Hessian and Burlap, at the
* expense of being tied to Java. Nevertheless, it is as easy to set up as
* Hessian and Burlap, which is its main advantage compared to RMI.
*
* @author Juergen Hoeller
* @since 1.1
* @see HttpInvokerClientInterceptor
* @see HttpInvokerProxyFactoryBean
* @see org.springframework.remoting.rmi.RmiServiceExporter
* @see org.springframework.remoting.caucho.HessianServiceExporter
* @see org.springframework.remoting.caucho.BurlapServiceExporter
*/
public class HttpInvokerServiceExporter extends RemoteInvocationSerializingExporter
implements HttpRequestHandler {
/**
* Reads a remote invocation from the request, executes it,
* and writes the remote invocation result to the response.
* @see #readRemoteInvocation(HttpServletRequest)
* @see #invokeAndCreateResult(org.springframework.remoting.support.RemoteInvocation, Object)
* @see #writeRemoteInvocationResult(HttpServletRequest, HttpServletResponse, RemoteInvocationResult)
*/
public void handleRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
RemoteInvocation invocation = readRemoteInvocation(request);
RemoteInvocationResult result = invokeAndCreateResult(invocation, getProxy());
writeRemoteInvocationResult(request, response, result);
}
catch (ClassNotFoundException ex) {
throw new NestedServletException("Class not found during deserialization", ex);
}
}
/**
* Read a RemoteInvocation from the given HTTP request.
* <p>Delegates to
* {@link #readRemoteInvocation(javax.servlet.http.HttpServletRequest, java.io.InputStream)}
* with the
* {@link javax.servlet.ServletRequest#getInputStream() servlet request's input stream}.
* @param request current HTTP request
* @return the RemoteInvocation object
* @throws IOException in case of I/O failure
* @throws ClassNotFoundException if thrown by deserialization
*/
protected RemoteInvocation readRemoteInvocation(HttpServletRequest request)
throws IOException, ClassNotFoundException {
return readRemoteInvocation(request, request.getInputStream());
}
/**
* Deserialize a RemoteInvocation object from the given InputStream.
* <p>Gives {@link #decorateInputStream} a chance to decorate the stream
* first (for example, for custom encryption or compression). Creates a
* {@link org.springframework.remoting.rmi.CodebaseAwareObjectInputStream}
* and calls {@link #doReadRemoteInvocation} to actually read the object.
* <p>Can be overridden for custom serialization of the invocation.
* @param request current HTTP request
* @param is the InputStream to read from
* @return the RemoteInvocation object
* @throws IOException in case of I/O failure
* @throws ClassNotFoundException if thrown during deserialization
*/
protected RemoteInvocation readRemoteInvocation(HttpServletRequest request, InputStream is)
throws IOException, ClassNotFoundException {
ObjectInputStream ois = createObjectInputStream(decorateInputStream(request, is));
try {
return doReadRemoteInvocation(ois);
}
finally {
ois.close();
}
}
/**
* Return the InputStream to use for reading remote invocations,
* potentially decorating the given original InputStream.
* <p>The default implementation returns the given stream as-is.
* Can be overridden, for example, for custom encryption or compression.
* @param request current HTTP request
* @param is the original InputStream
* @return the potentially decorated InputStream
* @throws IOException in case of I/O failure
*/
protected InputStream decorateInputStream(HttpServletRequest request, InputStream is) throws IOException {
return is;
}
/**
* Write the given RemoteInvocationResult to the given HTTP response.
* @param request current HTTP request
* @param response current HTTP response
* @param result the RemoteInvocationResult object
* @throws IOException in case of I/O failure
*/
protected void writeRemoteInvocationResult(
HttpServletRequest request, HttpServletResponse response, RemoteInvocationResult result)
throws IOException {
response.setContentType(getContentType());
writeRemoteInvocationResult(request, response, result, response.getOutputStream());
}
/**
* Serialize the given RemoteInvocation to the given OutputStream.
* <p>The default implementation gives {@link #decorateOutputStream} a chance
* to decorate the stream first (for example, for custom encryption or compression).
* Creates an {@link java.io.ObjectOutputStream} for the final stream and calls
* {@link #doWriteRemoteInvocationResult} to actually write the object.
* <p>Can be overridden for custom serialization of the invocation.
* @param request current HTTP request
* @param response current HTTP response
* @param result the RemoteInvocationResult object
* @param os the OutputStream to write to
* @throws IOException in case of I/O failure
* @see #decorateOutputStream
* @see #doWriteRemoteInvocationResult
*/
protected void writeRemoteInvocationResult(
HttpServletRequest request, HttpServletResponse response, RemoteInvocationResult result, OutputStream os)
throws IOException {
ObjectOutputStream oos = createObjectOutputStream(decorateOutputStream(request, response, os));
try {
doWriteRemoteInvocationResult(result, oos);
}
finally {
oos.close();
}
}
/**
* Return the OutputStream to use for writing remote invocation results,
* potentially decorating the given original OutputStream.
* <p>The default implementation returns the given stream as-is.
* Can be overridden, for example, for custom encryption or compression.
* @param request current HTTP request
* @param response current HTTP response
* @param os the original OutputStream
* @return the potentially decorated OutputStream
* @throws IOException in case of I/O failure
*/
protected OutputStream decorateOutputStream(
HttpServletRequest request, HttpServletResponse response, OutputStream os) throws IOException {
return os;
}
}