MPSIDL: MpsSimpleExample (original) (raw)

Table of Contents

• 1 Example 1
  • 1.1 Scenario
  • 1.2 The Code
    * 1.2.1 MPS IDL File
    * 1.2.2 Client code
    * 1.2.3 Server code

1 Example 1

1.1 Scenario

Let's say we need to have two programs interact with each other. They need to be able to access each others' functionality - that is, one of them is providing a service to the other. Let's say that this service (it's a simple example, OK?) is to write out a log entry to a file.

1.2 The Code

All this code is available in the distribution, in the "test/MpsSimpleExample" directory. You will find there

• a working Java Logserver implementation
• a working C++ Logserver implementation
• a working C++ Logserver client
• the MPSIDL Logserver specification

1.2.1 MPS IDL File

We might choose to define part of the interface like this (logging.mps - [:loggingmps:]):

namespace Logging { interface LogServer { // Log a string to our current file. // Returns true for success, and false for failure. // We could have chosen to use exceptions in case of failure. bool logString(string toLog); } }

Performing the command

mpsidl -c -o logging logging.mps

produces the files logging.h and logging.cc, which contain definitions for C++ server stubs and client proxies implementing this interface.

1.2.2 Client code

One of our C++ programs needs to make use of this new functionality. Read the [:cplusplusclient:] code to see how to do so. Here's a fragment of that file:

MPS::InetTransport::initialise("", 0); refMPS::NamingService ns = MPS::getNamingService(); refLogging::LogServer logServer = Logging::LogServer::_attach(ns->resolve("Logserver"));

if (logServer->logString("Startup successful") == false) { // Couldn't write log message... ... } ...

1.2.3 Server code

We choose to implement the server in Java. Running the command

mpsidl -j logging.mps

creates the directory Logging/ which contains Java source code implementing package Logging, which provides both client- and server-side interfaces to the interface defined in logging.mps.

We write our implementation of the server like this ([:javaserver:]):

import org.hebe.mps.; import org.hebe.mps.naming.; import Logging.*;

class LogServerImpl implements LogServer { public static void main(String [] args) { try { NamingService ns = new NamingServiceProxy("mps:inet:localhost:9091:1"); LogServerServer lss = new LogServerServer("Logserver", new LogServerImpl()); ns.bind("Logserver", lss.getBoundName(), true); } catch (Exception e) { e.printStackTrace(); } }

private int index;

private LogServerImpl() {
index = 1;
}

public boolean logString(String str) {
System.out.println(Integer.toString(index++) + ": " + str);
return true;
}

}

The equivalent C++ code can be found at [:cplusplusserver:].

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(last modified 06 August 2001 by surazal)