WebSocket Connection

# WebSocket Connection

Catalyst Data Streams enables clients to receive real-time data by establishing a WebSocket connection to a channel. The client listens for published messages and processes them as they are received.

To subscribe to a channel, you must first generate a token pair, then create a WebSocket client with the token credentials, and finally add event listeners to handle incoming messages.

#### Sample Code Snippet
<br>

import com.zc.component.datastream.ZCDatastream;
import com.zc.component.datastream.beans.ZCCustomEvent;
import com.zc.component.datastream.beans.ZCDataStreamMessageEvent;
import com.zc.component.datastream.beans.ZCDataStreamsConfig;
import com.zc.component.datastream.beans.ZCTokenResponse;
import com.zc.component.datastream.websocket.ZCDataStreamsEventListener;
import com.zc.component.datastream.websocket.ZCDataStreamsWebSocket;

//Create a Data Streams instance
ZCDatastream datastream = ZCDatastream.getInstance();

//Define channel ID and user ID
String channelId = "30772000000631098";
Long userId = 30772000000631094L;

//Generate token pair
ZCTokenResponse tokenResponse = datastream.getTokenPair(channelId, userId);

//Extract token credentials
String key = tokenResponse.getKey();
String zuid = tokenResponse.getWssId();
String url = tokenResponse.getUrl();

//Create WebSocket configuration
ZCDataStreamsConfig config = new ZCDataStreamsConfig(
    url,
    zuid,
    key,
    false
);

//Create WebSocket client
ZCDataStreamsWebSocket webSocketClient = datastream.createWebSocketClient(config);

//Add event listener to handle WebSocket events
webSocketClient.addEventListener(new ZCDataStreamsEventListener() {
    @Override
    public void onOpen(ZCCustomEvent event) {
        //Subscribe after WebSocket opens
        webSocketClient.subscribe("-2");
    }

@Override
    public void onMessage(ZCDataStreamMessageEvent event) {
        //Handle event payload or bulk URL info
        if (event.getData() != null) {
            System.out.println("Data: " + event.getData());
        } else if (event.getUrl() != null && event.getMethod() != null) {
            System.out.println("API URL: " + event.getUrl());
            System.out.println("Method: " + event.getMethod());
        }

//Acknowledge to receive the next message
        webSocketClient.sendAck();
    }

@Override
    public void onClose(ZCCustomEvent event) {
        System.out.println("Closed: " + event.getMessage());
    }

@Override
    public void onError(ZCCustomEvent event) {
        //Log error
        System.err.println("Error: " + event.getMessage());
    }

@Override
    public void onPong(ZCCustomEvent event) {
        System.out.println("Pong: " + event.getMessage());
    }
});

<br>

### WebSocket Client Methods

The ZCDataStreamsWebSocket client provides the following methods to manage the WebSocket connection and subscription.

<table class="content-table">
	<thead>
		<tr>
			<th class="w30p">Method</th>
			<th class="w70p">Description</th>
		</tr>
	</thead>
	<tbody>
		<tr>
			<td>subscribe(String subscribeType)</td>
			<td>Subscribes to the channel with the specified subscribe type. Throws ZCDataStreamException.</td>
		</tr>
		<tr>
			<td>subscribe()</td>
			<td>Subscribes to the channel with the default subscribe type. Throws ZCDataStreamException.</td>
		</tr>
		<tr>
			<td>unsubscribe()</td>
			<td>Unsubscribes from the channel. Throws ZCDataStreamException.</td>
		</tr>
		<tr>
			<td>sendAck()</td>
			<td>Sends an acknowledgement to receive the next streaming data.</td>
		</tr>
		<tr>
			<td>close()</td>
			<td>Closes the WebSocket connection manually.</td>
		</tr>
		<tr>
			<td>isConnected()</td>
			<td>Returns whether the connection is currently open, as a boolean.</td>
		</tr>
		<tr>
			<td>getConnectionState()</td>
			<td>Returns the current connection state as a String.</td>
		</tr>
		<tr>
			<td>getSessionInfo()</td>
			<td>Returns the ZCSessionInfo of the active session.</td>
		</tr>
	</tbody>
</table>

Catalyst Data Streams enables clients to receive real-time data by establishing a WebSocket connection to a channel. The client listens for published messages and processes them as they are received.

To subscribe to a channel, you must first generate a token pair, then create a WebSocket client with the token credentials, and finally add event listeners to handle incoming messages.

Sample Code Snippet

Package Imports
copy

         import com.zc.component.datastream.ZCDatastream;
import com.zc.component.datastream.beans.ZCCustomEvent;
import com.zc.component.datastream.beans.ZCDataStreamMessageEvent;
import com.zc.component.datastream.beans.ZCDataStreamsConfig;
import com.zc.component.datastream.beans.ZCTokenResponse;
import com.zc.component.datastream.websocket.ZCDataStreamsEventListener;
import com.zc.component.datastream.websocket.ZCDataStreamsWebSocket;
    

copy

//Create a Data Streams instance
ZCDatastream datastream = ZCDatastream.getInstance();
//Define channel ID and user ID
String channelId = “30772000000631098”;
Long userId = 30772000000631094L;
//Generate token pair
ZCTokenResponse tokenResponse = datastream.getTokenPair(channelId, userId);
//Extract token credentials
String key = tokenResponse.getKey();
String zuid = tokenResponse.getWssId();
String url = tokenResponse.getUrl();
//Create WebSocket configuration
ZCDataStreamsConfig config = new ZCDataStreamsConfig(
url,
zuid,
key,
false
);
//Create WebSocket client
ZCDataStreamsWebSocket webSocketClient = datastream.createWebSocketClient(config);
//Add event listener to handle WebSocket events
webSocketClient.addEventListener(new ZCDataStreamsEventListener() {
@Override
public void onOpen(ZCCustomEvent event) {
//Subscribe after WebSocket opens
webSocketClient.subscribe("-2");
}
@Override
public void onMessage(ZCDataStreamMessageEvent event) {
    //Handle event payload or bulk URL info
    if (event.getData() != null) {
        System.out.println("Data: " + event.getData());
    } else if (event.getUrl() != null && event.getMethod() != null) {
        System.out.println("API URL: " + event.getUrl());
        System.out.println("Method: " + event.getMethod());
    }

    //Acknowledge to receive the next message
    webSocketClient.sendAck();
}

@Override
public void onClose(ZCCustomEvent event) {
    System.out.println("Closed: " + event.getMessage());
}

@Override
public void onError(ZCCustomEvent event) {
    //Log error
    System.err.println("Error: " + event.getMessage());
}

@Override
public void onPong(ZCCustomEvent event) {
    System.out.println("Pong: " + event.getMessage());
}

});

WebSocket Client Methods

The ZCDataStreamsWebSocket client provides the following methods to manage the WebSocket connection and subscription.

Method	Description
subscribe(String subscribeType)	Subscribes to the channel with the specified subscribe type. Throws ZCDataStreamException.
subscribe()	Subscribes to the channel with the default subscribe type. Throws ZCDataStreamException.
unsubscribe()	Unsubscribes from the channel. Throws ZCDataStreamException.
sendAck()	Sends an acknowledgement to receive the next streaming data.
close()	Closes the WebSocket connection manually.
isConnected()	Returns whether the connection is currently open, as a boolean.
getConnectionState()	Returns the current connection state as a String.
getSessionInfo()	Returns the ZCSessionInfo of the active session.