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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.
*
* Contains some contributions under the Thrift Software License.
* Please see doc/old-thrift-license.txt in the Thrift distribution for
* details.
*/
using System;
using System.Text;
using Thrift.Transport;
using System.Collections.Generic;
using System.IO;
namespace Thrift.Protocol
{
/**
* TMultiplexedProcessor is a TProcessor allowing a single TServer to provide multiple services.
* To do so, you instantiate the processor and then register additional processors with it,
* as shown in the following example:
*
* TMultiplexedProcessor processor = new TMultiplexedProcessor();
*
* processor.registerProcessor(
* "Calculator",
* new Calculator.Processor(new CalculatorHandler()));
*
* processor.registerProcessor(
* "WeatherReport",
* new WeatherReport.Processor(new WeatherReportHandler()));
*
* TServerTransport t = new TServerSocket(9090);
* TSimpleServer server = new TSimpleServer(processor, t);
*
* server.serve();
*/
public class TMultiplexedProcessor : TProcessor
{
private Dictionary<String,TProcessor> ServiceProcessorMap = new Dictionary<String,TProcessor>();
/**
* 'Register' a service with this TMultiplexedProcessor. This allows us to broker
* requests to individual services by using the service name to select them at request time.
*
* Args:
* - serviceName Name of a service, has to be identical to the name
* declared in the Thrift IDL, e.g. "WeatherReport".
* - processor Implementation of a service, ususally referred to as "handlers",
* e.g. WeatherReportHandler implementing WeatherReport.Iface.
*/
public void RegisterProcessor(String serviceName, TProcessor processor)
{
ServiceProcessorMap.Add(serviceName, processor);
}
private void Fail( TProtocol oprot, TMessage message, TApplicationException.ExceptionType extype, string etxt)
{
TApplicationException appex = new TApplicationException( extype, etxt);
TMessage newMessage = new TMessage(message.Name, TMessageType.Exception, message.SeqID);
oprot.WriteMessageBegin(newMessage);
appex.Write( oprot);
oprot.WriteMessageEnd();
oprot.Transport.Flush();
}
/**
* This implementation of process performs the following steps:
*
* - Read the beginning of the message.
* - Extract the service name from the message.
* - Using the service name to locate the appropriate processor.
* - Dispatch to the processor, with a decorated instance of TProtocol
* that allows readMessageBegin() to return the original TMessage.
*
* Throws an exception if
* - the message type is not CALL or ONEWAY,
* - the service name was not found in the message, or
* - the service name has not been RegisterProcessor()ed.
*/
public bool Process(TProtocol iprot, TProtocol oprot)
{
/* Use the actual underlying protocol (e.g. TBinaryProtocol) to read the
message header. This pulls the message "off the wire", which we'll
deal with at the end of this method. */
try
{
TMessage message = iprot.ReadMessageBegin();
if ((message.Type != TMessageType.Call) && (message.Type != TMessageType.Oneway))
{
Fail(oprot, message,
TApplicationException.ExceptionType.InvalidMessageType,
"Message type CALL or ONEWAY expected");
return false;
}
// Extract the service name
int index = message.Name.IndexOf(TMultiplexedProtocol.SEPARATOR);
if (index < 0)
{
Fail(oprot, message,
TApplicationException.ExceptionType.InvalidProtocol,
"Service name not found in message name: " + message.Name + ". " +
"Did you forget to use a TMultiplexProtocol in your client?");
return false;
}
// Create a new TMessage, something that can be consumed by any TProtocol
string serviceName = message.Name.Substring(0, index);
TProcessor actualProcessor;
if (!ServiceProcessorMap.TryGetValue(serviceName, out actualProcessor))
{
Fail(oprot, message,
TApplicationException.ExceptionType.InternalError,
"Service name not found: " + serviceName + ". " +
"Did you forget to call RegisterProcessor()?");
return false;
}
// Create a new TMessage, removing the service name
TMessage newMessage = new TMessage(
message.Name.Substring(serviceName.Length + TMultiplexedProtocol.SEPARATOR.Length),
message.Type,
message.SeqID);
// Dispatch processing to the stored processor
return actualProcessor.Process(new StoredMessageProtocol(iprot, newMessage), oprot);
}
catch (IOException)
{
return false; // similar to all other processors
}
}
/**
* Our goal was to work with any protocol. In order to do that, we needed
* to allow them to call readMessageBegin() and get a TMessage in exactly
* the standard format, without the service name prepended to TMessage.name.
*/
private class StoredMessageProtocol : TProtocolDecorator
{
TMessage MsgBegin;
public StoredMessageProtocol(TProtocol protocol, TMessage messageBegin)
:base(protocol)
{
this.MsgBegin = messageBegin;
}
public override TMessage ReadMessageBegin()
{
return MsgBegin;
}
}
}
}
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