= Exercise 3: Socket Programming using New MobilityFirst NetAPI =

[[TOC(Tutorials/oMF*, depth=2)]]


== !Design/Setup ==

=== Objective: ===

In this exercise we will learn to write, compile, and run a simple content distribution application using !MobilityFirst's new socket API. We will then modify the program to utilize !MobilityFirst's native support for point to multi-point delivery services such as anycast and multicast to enable more flexible delivery options.

=== Develop Sender and Receiver Applications with MF Socket API ===

The following Java application shows the key pieces of the sender application that sends a file to a receiver known to the sender by its GUID and to then receive a confirmation message from the receiver:

{{{
#!java
//Simple class used to test the java api


//jmfapi needs to be in the classpath
import java.io.*;
import java.util.*;
import java.nio.file.*;
import edu.rutgers.winlab.jmfapi.*;
import edu.rutgers.winlab.jmfapi.GUID;

class Sender{
    private static void usage(){
        System.out.println("Usage:");
        System.out.println("sender <my_GUID> <file_to_send> <dst_GUID>");
    }
    public static void main(String []argv){
        if(argv.length < 3){
            usage();
            return;
        }
        String scheme = "basic";
        GUID srcGUID = null, dstGUID;
        srcGUID = new GUID(Integer.parseInt(argv[0]));
        Path file = FileSystems.getDefault().getPath(argv[1]);
        dstGUID = new GUID(Integer.parseInt(argv[2]));
        JMFAPI sender = new JMFAPI();
        try{
            if(srcGUID!=null) sender.jmfopen(scheme, srcGUID);
            else sender.jmfopen(scheme);
            byte[] fileArray;
            try {
                fileArray = Files.readAllBytes(file);
            } catch (IOException e){
                System.out.println("ERROR");
                return;
            }
            byte[] tempArray;
            int ret, read = 0;
            while(fileArray.length - read>=1000000){
                tempArray = Arrays.copyOfRange(fileArray, 0, 999999);
                sender.jmfsend(tempArray,1000000, dstGUID);
            }
            tempArray = Arrays.copyOfRange(fileArray, 0, fileArray.length - read - 1);
            sender.jmfsend(tempArray,fileArray.length - read, dstGUID);
            sender.jmfclose();
            System.out.println("Transmitted file");

                       //TODO receive confirmation

            System.out.println("Received confirmation");

        } catch (JMFException e){
            System.out.println(e.toString());
        }
    }
}
}}}

The following shows the corresponding receiver code:

{{{
#!java
//Simple class used to test the java api

import java.io.*;
import java.util.*;
import java.nio.file.*;
import edu.rutgers.winlab.jmfapi.*;

class Receiver{
    private static void usage(){
        System.out.println("Usage:");
        System.out.println("receiver [<my_GUID>]");
    }
    public static void main(String []argv){
        String scheme = "basic";
        GUID srcGUID = null;
        int i = 0;
        if(argv.length == 1) srcGUID = new GUID(Integer.parseInt(argv[0]));
        Path file = FileSystems.getDefault().getPath("temp.txt");
        try{
            Files.createFile(file);
        } catch(IOException e){
            try{
                Files.delete(file);
                Files.createFile(file);
            } catch(IOException e2){
                return;
            }
        }
        byte[] buf = new byte[1000000];
        int ret;
        JMFAPI receiver = new JMFAPI();
        try{
            if(srcGUID!=null) receiver.jmfopen(scheme, srcGUID);
            else receiver.jmfopen(scheme);
            while(i < 24954287){
                ret = receiver.jmfrecv_blk(null, buf, 1000000);
                try{
                    Files.write(file, buf, StandardOpenOption.APPEND);
                } catch (IOException e){
                    System.out.println(e.toString());
                }
                i += ret;

            }
                System.out.println("Received file");

                        //TODO send confirmation

            receiver.jmfclose();
        } catch (JMFException e){
            System.out.println(e.toString());
        }

    }
}
}}}


== Execute ==


==== Test !Sender/Receiver Applications ====

==== Add Second Receiver End Point to Topology ====

==== Modify Delivery Service Option to Add Multi-point Delivery ====

The following code snippet shows the modified portion of the code to request Multicast delivery option while transfering the file:

{{{
#!java

}}}


== Finish ==