JavaScript

Send a 4-byte Length Prefix over a Socket

Demonstrates Socket.SendCount, which sends a four-byte length prefix in network byte order. This is typically used to tell the peer how many bytes follow.

Background. A length-prefixed framing scheme sends the byte count of a message before the message body, so the receiver knows exactly how many bytes to read with a counted receive.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

JavaScript

var success = false;

var socket = new CkSocket();

//  Connect to the server using TLS.
var bTls = true;
var maxWaitMs = 5000;
success = socket.Connect("example.com",5000,bTls,maxWaitMs);
if (success == false) {
    console.log(socket.LastErrorText);
    return;
}

//  Send a four-byte length prefix in network byte order.  A common framing pattern is to send the
//  number of bytes in a message before the message itself, so the peer knows exactly how many bytes
//  to read.
var messageLength = 512;
success = socket.SendCount(messageLength);
if (success == false) {
    console.log(socket.LastErrorText);
    return;
}

console.log("Length prefix sent.");