Hello World TRP in Java

How to write a Java TRP client program that :

  • Sends a HelloRequest to Trisul and prints the HelloResponse

Also see : Programming model , Messages and Fields

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.

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.

You may also use JAR files or CLASSPATH this directory directly.

$ 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()
                              .setHelloRequest( TRP.Trp.HelloRequest.newBuilder()

        // 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());

        // 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];

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

        // Print response fields
        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);

    public static void main(String[] args) {
            Socket s  = new Socket(args[0],12001);
        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 12001
[akhil@localhost s4]$ java TestTRP 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]$