Java

WebSocket Send/Receive Binary Data

See more WebSocket Examples

Demonstrates how to send and receive binary data on a websocket. This example uses Chilkat's websocket test echo server at ws://websockets.chilkat.io/wsChilkatEcho.ashx

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

Chilkat2 Java

import com.chilkatsoft.chilkat2.BinData;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Rest;
import com.chilkatsoft.chilkat2.WebSocket;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        WebSocket ws = new WebSocket();

        // For brevity, this example does not check for errors when etablishing the WebSocket connection.
        // See Establish WebSocket Connection for more complete sample code for making the connection.

        Rest rest = new Rest();
        // Connect to websockets.chilkat.io
        // IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back.
        // IMPORTANT: The websockets.chilkat.io server imposes the following limitations:
        // ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.
        rest.connect("websockets.chilkat.io", 80, false, false);
        ws.useConnection(rest);
        ws.addClientHeaders();
        String responseBodyIgnored = rest.fullRequestNoBody("GET", "/wsChilkatEcho.ashx");
        try {
            ws.validateServerHandshake();
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // This example sends a small JPG file (about 7KB) in a websocket frame.
        BinData jpgData = new BinData();
        jpgData.loadFile("qa_data/jpg/starfish.jpg");

        System.out.println("Number of bytes to send = " + jpgData.getNumBytes());

        // Send a frame containing the JPG image data.
        // This will be the first and final frame, and therefore this constitutes the entire message.
        boolean finalFrame = true;
        try {
            ws.sendFrameBd(jpgData, finalFrame);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Read the echoed binary frame(s).
        // (We sent the JPG file in a single frame, but we may receive the echo in multiple frames, but it will be one message.)
        // Read an incoming frames until we receive the final frame.
        boolean receivedFinalFrame = false;
        while (!receivedFinalFrame) {
            // The ws object is accumulating the received data internally.  Once we get the final frame, we'll get the
            // accumulated data which should constitute the entire JPG.
            try {
                ws.readFrame();
            } catch (ChilkatException e) {
                System.out.println("Failed to receive a frame");
                System.out.println("ReadFrame fail reason = " + ws.getReadFrameFailReason());
                System.out.println(e.getLastErrorText());
                return;
            }

            receivedFinalFrame = ws.getFinalFrame();

            // Show the opcode and final frame bit for the frame just received:
            System.out.println("Frame opcode: " + ws.getFrameOpcode());
            System.out.println("Final frame: " + receivedFinalFrame);
        }

        // Get the accumulated received data.
        BinData jpgReceivedData = new BinData();
        ws.getFrameDataBd(jpgReceivedData);
        System.out.println("Received " + jpgReceivedData.getNumBytes() + " bytes");

        // Save the received JPG to a file so we can check it..
        jpgReceivedData.writeFile("qa_output/starfish_ws.jpg");

        // Close the websocket connection.
        try {
            ws.sendClose(true, 1000, "Closing this websocket.");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Read the Close response.
        try {
            ws.readFrame();
        } catch (ChilkatException e) {
            System.out.println("ReadFrame fail reason = " + ws.getReadFrameFailReason());
            System.out.println(e.getLastErrorText());
            return;
        }

        // Should receive the "Close" opcode.
        System.out.println("Received opcode: " + ws.getFrameOpcode());
        // Should be the same status code we sent (1000)
        System.out.println("Received close status code: " + ws.getCloseStatusCode());
        // The server may echo the close reason.  If not, this will be empty.
        System.out.println("Echoed close reason: " + ws.getCloseReason());

        System.out.println("Success.");
    }
}