Tech Brainwave

Introduction
Abbrevation for Mina is ‘Multipurpose Infrastructure for Network Applications’, which is a network application framework to develop highly scalable and performant network applications. In this article, let us see how to create a simple client/server application using Apache Mina 2.0.x.

Required jars

1. Apache Mina 2.0.x jars
2. slf4j-api.jar
3. slf4k-jdk14.jar

Server part
For the server part, Two classes named “MinaServer” and “MinaServerHandler” has been used. The “MinaServer” class contains a main method and an interface named “IoAcceptor” is used to accept the incoming connections from the client and that fires the event to the handler. Two filters has been used, the first one is the “LoggingFilter” which logs all the events and requests and the second one is the “ProtocolCodecFilter” which is used to convert an incoming ByteBuffer into message POJO. The code for the “MinaServer” class is given below,

MinaServer.java

package com.sample.timeserver;

/**
* @author giftsam
*/
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.charset.Charset;

import org.apache.mina.core.session.IdleStatus;
import org.apache.mina.core.service.IoAcceptor;
import org.apache.mina.filter.codec.ProtocolCodecFilter;
import org.apache.mina.filter.codec.textline.TextLineCodecFactory;
import org.apache.mina.filter.logging.LoggingFilter;
import org.apache.mina.transport.socket.nio.NioSocketAcceptor;

public class MinaServer
{
private static final int PORT = 1234;

public static void main(String[] args) throws IOException
{
IoAcceptor acceptor = new NioSocketAcceptor();

acceptor.getFilterChain().addLast("logger", new LoggingFilter());
acceptor.getFilterChain().addLast("codec", new ProtocolCodecFilter(new TextLineCodecFactory(Charset.forName("UTF-8"))));

acceptor.setHandler(new MinaServerHandler());
acceptor.getSessionConfig().setReadBufferSize(2048);
acceptor.getSessionConfig().setIdleTime(IdleStatus.BOTH_IDLE, 10);
acceptor.bind(new InetSocketAddress(PORT));
}
}

Next let us create a custom handler named “MinaServerHandler”, which contains four methods. The first method “sessionOpened” is called when the session is opened and it is used to set the session idle time. The second method “receiveMessage” is used to receive the message sent by the client. The other two methods “sessionIdle” is used to close the session when it was idle for 10 secs and the fourth method “exceptionCaught” is used to close the session when an exception occured. The code for the “MinaServerHandler” class is given below,

MinaServerHandler.java

package com.sample.timeserver;
import org.apache.mina.core.session.IdleStatus;
import org.apache.mina.core.service.IoHandlerAdapter;
import org.apache.mina.core.session.IoSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
* @author giftsam
*/
public class MinaServerHandler extends IoHandlerAdapter
{
private final Logger logger = (Logger) LoggerFactory.getLogger(getClass());

@Override
public void sessionOpened(IoSession session)
{
// set idle time to 10 seconds
session.getConfig().setIdleTime(IdleStatus.BOTH_IDLE, 10);

session.setAttribute("Values: ");
}

@Override
public void messageReceived(IoSession session, Object message)
{
logger.info("Message received in the server..");
logger.info("Message is: " + message.toString());
}

@Override
public void sessionIdle(IoSession session, IdleStatus status)
{
logger.info("Disconnecting the idle.");
// disconnect an idle client
session.close();
}

@Override
public void exceptionCaught(IoSession session, Throwable cause)
{
// close the connection on exceptional situation
session.close();
}

}

Client part
For the client part “MinaClient” and “MinaClientHandler” class has been used. In the “MinaClient” class the “IoConnector” interface is used to communicate with the server and that fires the event to the handler. Like the server part, The same “LoggingFilter” and “ProtocolCodecFilter” has been used. An interface named “ConnectFuture” is used to windup the asynchronous connection requests.The code for the “MinaClient” class is given below,

MinaClient.java

package com.sample.timeserver;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.charset.Charset;
import org.apache.mina.core.future.ConnectFuture;
import org.apache.mina.core.service.IoConnector;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolCodecFilter;
import org.apache.mina.filter.codec.textline.TextLineCodecFactory;
import org.apache.mina.filter.logging.LoggingFilter;
import org.apache.mina.transport.socket.nio.NioSocketConnector;

/**
* @author giftsam
*/
public class MinaClient
{
private static final int PORT = 1234;

public static void main(String[] args) throws IOException, InterruptedException
{
IoConnector connector = new NioSocketConnector();
connector.getSessionConfig().setReadBufferSize(2048);

connector.getFilterChain().addLast("logger", new LoggingFilter());
connector.getFilterChain().addLast("codec", new ProtocolCodecFilter(new TextLineCodecFactory(Charset.forName("UTF-8"))));

connector.setHandler(new MinaClientHandler("Hello Server.."));
ConnectFuture future = connector.connect(new InetSocketAddress("172.108.0.12", PORT));
future.awaitUninterruptibly();

if (!future.isConnected())
{
return;
}
IoSession session = future.getSession();
session.getConfig().setUseReadOperation(true);
session.getCloseFuture().awaitUninterruptibly();

System.out.println("After Writing");
connector.dispose();

}

}

For the handler, Like the server part the same methods “sessionOpened”, “messageReceived” and “exceptionCaught” has been used. The code for the “MinaClientHandler” class is given below,

MinaClientHandler.java

package com.sample.timeserver;
import org.apache.mina.core.service.IoHandlerAdapter;
import org.apache.mina.core.session.IoSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* @author giftsam
*/
public class MinaClientHandler extends IoHandlerAdapter
{
private final Logger logger = (Logger) LoggerFactory.getLogger(getClass());
private final String values;
private boolean finished;

public MinaClientHandler(String values)
{
this.values = values;
}

public boolean isFinished()
{
return finished;
}

@Override
public void sessionOpened(IoSession session)
{
session.write(values);
}

@Override
public void messageReceived(IoSession session, Object message)
{
logger.info("Message received in the client..");
logger.info("Message is: " + message.toString());
}

@Override
public void exceptionCaught(IoSession session, Throwable cause)
{
session.close();
}

}

Now its time to test the preceding codes, First the code “MinaServer” should be executed and then execute the “MinaClient”, the outcome of the codes will looks like the below,

MinaServer – Output

Dec 8, 2010 8:31:49 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: CREATED
Dec 8, 2010 8:31:49 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: OPENED
Dec 8, 2010 8:31:49 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: RECEIVED: HeapBuffer[pos=0 lim=5 cap=2048: 54 65 73 74 0A]
Message received in the server..
Message is: Hello Server..
Dec 8, 2010 8:32:00 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: IDLE
Dec 8, 2010 8:32:00 PM com.sample.timeserver.TimeServerHandler sessionIdle
INFO: Disconnecting the idle.
Dec 8, 2010 8:32:00 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: CLOSED

MinaClient – Output

Dec 8, 2010 8:31:49 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: CREATED
Dec 8, 2010 8:31:49 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: OPENED
Dec 8, 2010 8:31:49 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: SENT: HeapBuffer[pos=0 lim=0 cap=0: empty]
Dec 8, 2010 8:32:00 PM org.apache.mina.filter.logging.LoggingFilter log
INFO: CLOSED
Client completed..

Thats all folks. I hope this article clearly explains the simple client/server application using Apache Mina 2.0.x. If you find this article is useful for you, dont forget to leave your valuable comments. Have a joyous code day.