Newbie socket read write question

Question

Hello all,
I need to develop a simple client application in java using socket
programming. The client will connect to a server implemented in VC++.
The server part has been implemented so I need to develop only the
client part.
Could anybody help me with a simple program that sends data to the
server and then prints out whatever the server sends back for the
given request.
The client and the server communicate using a specified format of bytes as shown below. I do not know how to read those bytes using the sizes as the token.
I know how to connect to the server but I do not know the proper way of sending and receiving data.
connection = new Socket(destination, port);
outStream = new DataOutputStream connection.getOutputStream());
//send the ID 1 to the server
outStream.writeByte(1);
//send the total packet size
//send the data
Thanks in advance
Pertheli
The client and server communicates with the following packet format
shown below. Each packet will have header, size and data as shown
PACKET
offset(byte) contents
0 byte PACKET ID
1 byte PACKET length (motolora format)
2 byte
3 byte DATA * n (motolora format)
4 byte
5 byte ~ DATA
n byte
Now for a For say PACKET ID = 1
we send the data to the server like
0 byte (motolora format)
3 byte
Then from the VC server we recieve the data in the format such as
0 byte Name
43 byte
44 byte Status

Answer 1

Hi!
Try this...
Socket connection = new Socket(server,port);
// use a Buffered*Stream as often as possible, because
// of the IP Packet Lengths...It Increases the
// network performance (but you DON'T need it)
// you'll send bytes or messages to the server in
// the OutputStream and receive answers from the
// server in the InputStream
int packetOutputBufferSize = connection.getSendBufferSize();
int packetInputBufferSize = connection.getReceiveBufferSize();
BufferedOutputStream bos = new BufferedOutputStream(connection.getOutputStream(),packetOutputBufferSize);
BufferedInputStream bis = new BufferedInputStream(connection.getInputStream(),packetInputBufferSize);
// sending data through the socket
// create your packet in a byte array
byte[] output = new byte[<packet-lenght>];
output[0]=<packet ID>
output[1]=....
bos.write(output,0,output.length);
// receiving data from the socket
byte[] input = new byte[<max-packet-length>];
int read=0;
int length=0;
while ((read=bis.read(input,length,(input.length-length)) > 0) {
length+=read;
if (length>=input.length) break;
// now your server output is in the bytearray 'input'
If it isn't possible to set a max packet size, use a bytearray as buffer and write it content into a ByteArrayOutputStream, thats something like a resizable write-only byte array. (you'll get the full content of it by calling the method ByteArrayOutputStream.toByteArray())
Maybe you want to check the packet content during receiving the bytes from the socket: Then you should use some read() method from the InputStream, but thats not very powerful.