(JavaScript) Transfer a File using Sockets (TLS or non-TLS)

Demonstrates how to two programs, one a socket writer and the other a socket reader, can transfer a file. The connection can be TLS or a regular non-encrypted TCP connection.

Note: This example requires Chilkat v11.0.0 or greater.

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.

var success = false;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// On the sending side, we'll load the file into a BinData object and send.
// On the receiving side, we'll read from the socket connection into a BinData, and save to a file.
// This example assumes the file is not crazy-large, and that the entire contents
// can fit into memory.  
// (If the file is too large for memory, there are other ways to send. It just involves streaming or 
// sending the file chunk-by-chunk..)

// This section of code is for the sender.
var bdToSend = new CkBinData();
success = bdToSend.LoadFile("somePath/someFile.dat");
// Assume success for the example...

var sndSock = new CkSocket();
var bUseTls = true;
var port = 5555;
var maxWaitMs = 5000;
success = sndSock.Connect("some_domain_or_ip.com",port,bUseTls,maxWaitMs);
// Assume success for the example...

// Tell the receiver how many bytes are coming.
var numBytes = bdToSend.NumBytes;
var bBigEndian = true;
success = sndSock.SendInt32(numBytes,bBigEndian);

// Send the file data (sends the entire contents of bdToSend).
success = sndSock.SendBd(bdToSend,0,0);

// Get an acknowledgement.
success = sndSock.ReceiveInt32(bBigEndian);
if (success == false) {
    console.log(sndSock.LastErrorText);
    return;
}

// Did the receiver get the correct number of bytes?
if (sndSock.ReceivedInt !== numBytes) {
    console.log("The receiver did not acknowledge with the correct number of bytes.");
    return;
}

console.log("File sent!");

// ------------------------------------------------------------------------------------
// The code below is for the receiving side (running on some other computer..)

var listenSock = new CkSocket();

success = listenSock.BindAndListen(5555,25);
if (success == false) {
    console.log(listenSock.LastErrorText);
    return;
}

// Get the next incoming connection
// Wait a maximum of 20 seconds (20000 millisec)
var rcvSock = new CkSocket();
success = listenSock.AcceptNext(20000,rcvSock);
if (success == false) {
    console.log(listenSock.LastErrorText);
    return;
}

// The sender will first send the big-endian integer for the number of bytes
// that are forthcoming..
success = rcvSock.ReceiveInt32(bBigEndian);
if (success !== true) {
    console.log(rcvSock.LastErrorText);
    return;
}

var numBytesComing = rcvSock.ReceivedInt;

// Receive that many bytes..
var bdReceived = new CkBinData();
success = rcvSock.ReceiveBdN(numBytesComing,bdReceived);
if (success !== true) {
    console.log(rcvSock.LastErrorText);
    return;
}

// Acknowledge the sender by sending back the number of bytes we received.
success = rcvSock.SendInt32(bdReceived.NumBytes,bBigEndian);

// Close the connection.
var maxWaitMs = 20;
rcvSock.Close(maxWaitMs);

// Save the received data to a file.
success = bdReceived.WriteFile("somePath/someFile.dat");
// Assume success for the example...

console.log("File received!");