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How can I send Large data to WebSocket in Java Script?

Using below code I am able to send data for 126 characters but not more then this. (Written in C#)

public static void SendData(string text)
    {

        foreach (SocketClient client in ClientList)
        {
            if (client.Client.Connected)
            {
                try
                {

                    NetworkStream l_Stream = client.Client.GetStream();

                    List<byte> lb = new List<byte>();
                    lb = new List<byte>();
                    lb.Add(0x81);
                    int size = text.Length;
                    lb.Add((byte)size);
                    lb.AddRange(Encoding.UTF8.GetBytes(text));
                    l_Stream.Write(lb.ToArray(), 0, size + 2);

                }
                catch
                {
                    CloseClient(client);
                }
            }
        }
    }
}

Can someone please help me? I tried to use so many things but none of them are working for me.

I am using Chrome 25 for the same.

How can I send Large data to WebSocket in Java Script?

Using below code I am able to send data for 126 characters but not more then this. (Written in C#)

public static void SendData(string text)
    {

        foreach (SocketClient client in ClientList)
        {
            if (client.Client.Connected)
            {
                try
                {

                    NetworkStream l_Stream = client.Client.GetStream();

                    List<byte> lb = new List<byte>();
                    lb = new List<byte>();
                    lb.Add(0x81);
                    int size = text.Length;
                    lb.Add((byte)size);
                    lb.AddRange(Encoding.UTF8.GetBytes(text));
                    l_Stream.Write(lb.ToArray(), 0, size + 2);

                }
                catch
                {
                    CloseClient(client);
                }
            }
        }
    }
}

Can someone please help me? I tried to use so many things but none of them are working for me.

I am using Chrome 25 for the same.

• c#
• javascript
• websocket

Share Improve this question Follow edited Dec 31, 2012 at 17:07 Erik Philips 54.6k1111 gold badges131131 silver badges156156 bronze badges asked Dec 31, 2012 at 14:38 Sanket ShahSanket Shah 48122 gold badges88 silver badges1717 bronze badges 2

• What is the problem with this code? – usr Commented Dec 31, 2012 at 18:21
• It won't send data more then 126 characters. – Sanket Shah Commented Jan 2, 2013 at 8:02

Add a comment  | 

4 Answers 4

Sorted by: Reset to default 33

This is how a websocket frame looks according to RFC 6455:

  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-------+-+-------------+-------------------------------+
 |F|R|R|R| opcode|M| Payload len |    Extended payload length    |
 |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
 |N|V|V|V|       |S|             |   (if payload len==126/127)   |
 | |1|2|3|       |K|             |                               |
 +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
 |     Extended payload length continued, if payload len == 127  |
 + - - - - - - - - - - - - - - - +-------------------------------+
 |                               |Masking-key, if MASK set to 1  |
 +-------------------------------+-------------------------------+
 | Masking-key (continued)       |          Payload Data         |
 +-------------------------------- - - - - - - - - - - - - - - - +
 :                     Payload Data continued ...                :
 + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
 |                     Payload Data continued ...                |
 +---------------------------------------------------------------+

You are setting the payload length of the websocket frame in byte 1 (the 2nd byte - first byte is byte 0). A byte can only have 256 states. But the first bit of byte 1 is used for the masking flag. So you can only represent values from 0 to 127.

When the payload length is larger than 125, you have to set byte 1 to 126 and put the length into byte 2 and 3 ("Extended payload length"). When your payload is even longer than 65535 bytes, you have to set byte 1 to 127 and put the payload length into the bytes 2-9 ("Extended payload length" and "Extended payload length continued"). When your payload length is even larger than 64bit (16 Exabyte, or about 16 million Terabyte), then... you should rather send a bunch of trucks filled with hard drives.

More details about that can be found in the official Websocket RFC.

You can send any size of data to WebSocket but large data will be fragmented.

Check this: https://datatracker.ietf.org/doc/html/draft-ietf-hybi-thewebsocketprotocol-17#section-5 and 5.4

and

pastebin.com/TxGZaHTY

and

http://buildnewgames.com/websockets/

for more info.

Referred from this blog. There could be a limit for single payload size to send and receive in the WebSocket server. For instance, in tomcat, by default it is 8192 bytes, checkout org.apache.tomcat.websocket.textBufferSize in tomcat's doc.

So, make sure if there is any payload size limit in your WebSocket server, if yes then receive it as partial payloads.

package GoodExample;

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.HashMap;
import sun.misc.BASE64Encoder;

/**
*
* @author
* Anders, Improved by Christopher Price
 */
public class WebRTCSignal {

public static final int MASK_SIZE = 4;
public static final int SINGLE_FRAME_UNMASKED = 0x81;
private ServerSocket serverSocket;
private Socket socket;

public WebRTCSignal() throws IOException {
serverSocket = new ServerSocket(1337);
connect();
}

private void connect() throws IOException {
System.out.println("Listening");
socket = serverSocket.accept();
System.out.println("Got connection");
if(handshake()) {
    listenerThread();
}
}

private boolean handshake() throws IOException {
PrintWriter out = new PrintWriter(socket.getOutputStream());
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

HashMap<String, String> keys = new HashMap<>();
String str;
//Reading client handshake
while (!(str = in.readLine()).equals("")) {
    String[] s = str.split(": ");
    System.out.println();
    System.out.println(str);
    if (s.length == 2) {
    keys.put(s[0], s[1]);
    }
}
//Do what you want with the keys here, we will just use "Sec-WebSocket-Key"

String hash;
try {
    hash = new BASE64Encoder().encode(MessageDigest.getInstance("SHA-    1").digest((keys.get("Sec-WebSocket-Key") + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").getBytes()));
} catch (NoSuchAlgorithmException ex) {
    ex.printStackTrace();
    return false;
}

//Write handshake response
out.write("HTTP/1.1 101 Switching Protocols\r\n"
    + "Upgrade: websocket\r\n"
    + "Connection: Upgrade\r\n"
    + "Sec-WebSocket-Accept: " + hash + "\r\n"
     + "Origin: http://face2fame.com\r\n"
    + "\r\n");

out.flush();

return true;
}

private byte[] readBytes(int numOfBytes) throws IOException {
byte[] b = new byte[numOfBytes];
socket.getInputStream().read(b);
return b;
}

public void sendMessage(byte[] msg) throws IOException {
System.out.println("Sending to client");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BufferedOutputStream os = new BufferedOutputStream(socket.getOutputStream());
baos.write(SINGLE_FRAME_UNMASKED);
baos.write(msg.length);
baos.write(msg);
baos.flush();
baos.close();
convertAndPrint(baos.toByteArray());
os.write(baos.toByteArray(), 0, baos.size());
os.flush();
}

public void listenerThread() {
Thread t = new Thread(new Runnable() {
    @Override
    public void run() {
    try {
        while (true) {
        System.out.println("Recieved from client: " + reiceveMessage());
        System.out.println("Enter data to send");
        }
    } catch (IOException ex) {
        ex.printStackTrace();
    }
    }
});
t.start();
}

public String reiceveMessage() throws IOException {
byte[] buf = readBytes(2);
//dont use this byte[] buf2 = readBytes(4);
int extendedsize = 0;
System.out.println("Headers:");
if(!convertAndPrintHeader(buf)){ // This means we detected an extended message
    String CaryOverDetectiona = new String("");
    byte[] bufadder1 = buf.clone();
    byte[] bufadder2 = readBytes(2);
    byte[] array1and2 = new byte[bufadder1.length + bufadder2.length];
    System.arraycopy(bufadder1, 0, array1and2, 0, bufadder1.length);
    System.arraycopy(bufadder2, 0, array1and2, bufadder1.length, bufadder2.length);
    for (byte b : array1and2) {
        CaryOverDetectiona = (String.format("%02X ", b));
        System.out.print(CaryOverDetectiona);

}
    int i = ((array1and2[1] & 0xFF) - 0x80);
    //int c = ((array1and2[2] & 0xFF) - 0x80);
    //System.out.println(c+128);
    int j = ((array1and2[3] & 0xFF) - 0x80)+2;
    //System.out.println("The size of this uber message is" + j);
    extendedsize = i+j;
    System.out.println("Extended Size is" + extendedsize);
    //System.exit(0);

}
//convertAndPrint(buf2);// Check out the byte sizes
int opcode = buf[0] & 0x0F;
if (opcode == 8) {
    //Client want to close connection!
    System.out.println("Client closed!");
    socket.close();
    System.exit(0);
    return null;
} else {
   int payloadSize = getSizeOfPayload(buf[1]);
    if (extendedsize>=126){   
    payloadSize = extendedsize;}
    System.out.println("Payloadsize: " + payloadSize);
    buf = readBytes(MASK_SIZE + payloadSize);
    System.out.println("Payload:");
    convertAndPrint(buf);
    buf = unMask(Arrays.copyOfRange(buf, 0, 4), Arrays.copyOfRange(buf, 4, buf.length));

    String message = new String(buf);

    return message;
}
}

private int getSizeOfPayload(byte b) {
//Must subtract 0x80 from masked frames

int a = b & 0xff;
//System.out.println("PAYLOAD SIZE INT" + a);
return ((b & 0xFF) - 0x80);
}

private byte[] unMask(byte[] mask, byte[] data) {
for (int i = 0; i < data.length; i++) {
    data[i] = (byte) (data[i] ^ mask[i % mask.length]);
}
return data;
}
private boolean convertAndPrintHeader(byte[] bytes) {
   StringBuilder sb = new StringBuilder();
   String CaryOverDetection = new String();
   // We must test byte 2 specifically for this. In the next step we add length bytes perhaps?
   //for(int i = 0; i < bytes.length; i++) {
       //}
    for (byte b : bytes) {
        CaryOverDetection = (String.format("%02X ", b));
        if (CaryOverDetection.contains("FE")){

            return false;
        }
        sb.append(String.format("%02X ", b));
    }
    System.out.println(sb.toString());
    return true;

    }

private void convertAndPrint(byte[] bytes) {
StringBuilder sb = new StringBuilder();
for (byte b : bytes) {
    sb.append(String.format("%02X ", b));
}
System.out.println(sb.toString());
}

public static void main(String[] args) throws IOException, InterruptedException, NoSuchAlgorithmException {
WebRTCSignal j = new WebRTCSignal();
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
while (true) {
   System.out.println("Write something to the client!");
   j.sendMessage(br.readLine().getBytes());
}
}
}

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