Hello World TRP in Java

Step 1 : Install Protocol Buffers

You need a development environment for this step.

Go to http://code.google.com/p/protobuf/ and download the latest version.
Follow the instructions to install protobuf (usually the ./configure + make + make install routine)

To test whether the installation was successful try running protoc

root@vivek-hardy:~# protoc
Missing input file.
root@vivek-hardy:~#

Everything is fine if you get output similar to the above.

Step 2 : Install the Java SDK

Change to the protobuf directory and locate the java subdirectory.

Our goal here is to make a tar file containing the Java API files, we will then untar these files in our working directory where they can be found easily.

$ cd /opt/sware/protobuf-2.3.0/java
$ protoc --java_out=src/main/java -I../src ../src/google/protobuf/descriptor.proto
$ cd src/main/java
$ tar cvfz protobuf_java.tar.gz com/

Next untar the protobuf_java.tar.gz in our working directory (where we will be writing the TRP program).

Step 3 : Process the trp.proto file

protoc trp.proto --java_out .

This will create a TRP/trp.java file which contains all the Java bindings necessary.

Step 4 : Save and run this program

Lets directly run the sample program, then explain the code.

Download and save this in your working directory.

// Trisul Remote Protocol TRP Demo Java script
//
//dependency = javaprotobuf
//

import TRP.Trp;
import java.util.*;
import java.io.*;
import java.net.*;
import java.text.DateFormat;
import java.text.SimpleDateFormat;

class TestTRP {


    // Hello Request/Response on the given socket
    public static void SayHello(Socket s) throws IOException {

        // Build a Hello Request message
        TRP.Trp.Message req = TRP.Trp.Message.newBuilder()
                              .setTrpCommand(TRP.Trp.Message.Command.HELLO_REQUEST)
                              .setHelloRequest( TRP.Trp.HelloRequest.newBuilder()
                                                    .setStationId("TESTTRP1")
                                              )
                              .build();


        // Write to data to socket
        // Note that we do a writeInt() first containing the length of the serialized message
        byte [] outdata = req.toByteArray();
        DataOutputStream os  = new DataOutputStream(s.getOutputStream());
        os.writeInt(outdata.length);
        os.write(outdata,0,outdata.length);


        // Read data from socket
        // Note that we first readInt() the number of bytes, then read the exact number
        DataInputStream is  = new DataInputStream(s.getInputStream());
        int resplen = is.readInt();
        byte indata[] = new byte[resplen];
        is.read(indata,0,resplen);


        // Make the response TRP message
        TRP.Trp.Message resp = TRP.Trp.Message.parseFrom(indata);


        // Print response fields
        System.out.println("**************************************************");
        System.out.println("Trisul ID = " + resp.getHelloResponse().getTrisulId());
        System.out.println("Connection ID = " + resp.getHelloResponse().getConnectionId());
        System.out.println("Version String = " + resp.getHelloResponse().getVersionString());
        System.out.println("Connection Timings(in secs) = " + resp.getHelloResponse().getConnectionStartTime().getTvSec());
        System.out.println("Connection Timings(in usecs) = " + resp.getHelloResponse().getConnectionStartTime().getTvUsec());
        System.out.println("Active Connection Timings(in secs) = " + resp.getHelloResponse().getConnectionUpTime().getTvSec());
        System.out.println("Active Connection Timings(in usecs) = " + resp.getHelloResponse().getConnectionUpTime().getTvUsec());
        DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
        Date date = new Date(resp.getHelloResponse().getConnectionStartTime().getTvUsec());
        System.out.println (date);
        System.out.println("**************************************************");
    }



    public static void main(String[] args) {
        try
        {
            Socket s  = new Socket(args[0],12001);
            SayHello(s);
        }
        catch (IOException ex)
        {
        }
   }
}

Lets compile and run the program. The usage is
_java TestTRP <IP/hostname of Trisul> _

[akhil@localhost s4]$ javac TestTRP.java
[akhil@localhost s4]$ java TestTRP 192.168.1.7 12001
[akhil@localhost s4]$ java TestTRP 192.168.1.7 12001
Response length = 51
**************************************************
Trisul ID = Trisul
Connection ID = Conn-X
Version String = 1.0.535
Connection Timings(in secs) = 1282826314
Connection Timings(in usecs) = 749222
Active Connection Timings(in secs) = 0
Active Connection Timings(in usecs) = 193025
Thu Jan 01 05:42:29 IST 1970
**************************************************
[akhil@localhost s4]$