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.
    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.

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()  
.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> <port number>*

    [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]$