Java

Send and Receive WebSocket Messages

See more WebSocket Examples

This example how to send and receive websocket messages.

A WebSocket message can be composed of one or more frames. The simple case is where a single frame is both the first and last frame in a message. This is the case where the 1st frame in the message has the "final frame" bit set.

This example demonstrates sending and receiving multi-frame messages.

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.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 demonstrates sending and receiving a multi-frame message.

        // The websocket message will be composed of three text lines, each frame will contain a single line.

        // Send the 1st frame in the message.
        boolean finalFrame = false;
        try {
            ws.sendFrame("This is the 1st frame\r\n", finalFrame);

            // Send the 2nd frame in the message.
            ws.sendFrame("This is the 2nd frame\r\n", finalFrame);

            // Send the 3rd and final frame in the message.
            finalFrame = true;
            ws.sendFrame("This is the 3rd frame\r\n", finalFrame);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Read an incoming frames until we receive the final frame.
        // Note: It may be that the echo server (websockets.chilkat.io) responds with
        // the full message in a single final frame.
        boolean receivedFinalFrame = false;
        while (!receivedFinalFrame) {
            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);
        }

        // Return the message accumulated in the above calls to ReadFrame.
        String receivedMsg = ws.getFrameData();
        System.out.println("Received: " + receivedMsg);

        // 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.");
    }
}