Accessing AWS WebSocket using VertX HttpClient - amazon-web-services

Question

I have created an API Gateway with a Web Socket on AWS. I would like to connect to it using the HttpClient provided by VertX. I am using the following code for the client verticle:
public class WebSocketClient extends AbstractVerticle {
// application address replaced by [address]
protected final String host = "[address].execute-api.us-east-1.amazonaws.com";
protected final String path = "/dev";
protected final int port = 80;
protected final String webSocketAddress = "wss://[address].execute-api.us-east-1.amazonaws.com/dev";
#Override
public void start() throws Exception {
startClient(this.vertx);
}
protected void startClient(Vertx vertx) {
HttpClient client = vertx.createHttpClient();
client.webSocket(port, host, path, asyncWebSocket -> {
if (asyncWebSocket.succeeded()) {
WebSocket socket = asyncWebSocket.result();
System.out.println("Successfully connected. Node closing.");
socket.close().onFailure(throwable -> {
throwable.printStackTrace();
});
} else {
asyncWebSocket.cause().printStackTrace();
}
});
}
}
The same code works when I am testing it with a VertX server running on the localhost, so I assume that it is a question of the correct WebSocketConnectionOptions.
When I try to connect to the AWS socket using the HttpClient verticle, I get a "connection refused" error. Connecting to it using wscat works without problems.
Thanks a lot for your help.

Answer 1

This question is dealing with basically the same problem. I will post the solution here just to document a straight-forward way to use AWS ApiGateway Websockets with VertX.
So, the goal is to implement a VertX WebClient connected to a deployed AWS Api WebSocket Gateway which can be reached under the WsUri "wss://[address].execute-api.us-east-1.amazonaws.com/dev" (you will have to replace [address] by the address of your ApiGateway Websocket).
Here the code to set up the WebClient, connect to the Websocket, print out a success message, and then disconnect again:
public class WebSocketClient extends AbstractVerticle {
protected final String webSocketUrl = "wss://[address].execute-api.us-east-1.amazonaws.com/dev"
protected final String host = "[address].execute-api.us-east-1.amazonaws.com";
protected final String path = "/dev";
protected final int sslPort = 443;
#Override
public void start() throws Exception {
startClient(this.vertx);
}
protected void startClient(Vertx vertx) {
HttpClient client = vertx
.createHttpClient(new
HttpClientOptions().setDefaultHost(host).setDefaultPort(sslPort).setSsl(true));
// connect to the web socket
client.webSocket(path, asyncWebSocket -> {
if (asyncWebSocket.succeeded()) {
// executed on a successful connection
WebSocket socket = asyncWebSocket.result(); // use this for further communication
System.out.println("Successfully connected. Closing the socket.");
// Closing the socket
socket.close().onFailure(throwable -> {
throwable.printStackTrace();
});
} else {
// executed if the connection attempt fails
asyncWebSocket.cause().printStackTrace();
}
});
}
You can use the following class to run the example:
public class PlayWebSocket {
public static void main(String[] args) throws URISyntaxException{
Vertx vertx = Vertx.vertx();
WebSocketClient clientVerticle = new WebSocketClient();
vertx.deployVerticle(clientVerticle);
}
}
On the Java side, this should print the message about the successful connection and the closing of the socket. On the AWS side, the $connect and the $disconnect methods of the ApiGateway should be called. You can check this in the logs of your handler function(s) using CloudWatch.