A very simple vertx based websocket example connecting to Vertx SockJS.

WebSocketClientExample.kt

package info.usmans.blog.vertx.examples

import io.vertx.core.AbstractVerticle
import io.vertx.core.Vertx
import io.vertx.core.http.HttpClient
import io.vertx.core.http.WebSocketFrame
import io.vertx.core.json.JsonObject


fun main(args: Array<String>) {
    Vertx.vertx().deployVerticle(WebSocketClientExample())
    println("Running WebSockerClientExample!")
}

/**
 * A Vertx Verticle to connect to our custom websocket
 */
class WebSocketClientExample : AbstractVerticle() {

    override fun start() {
        val client = vertx.createHttpClient()
        openWebSocketConnection(client)
    }

    private fun openWebSocketConnection(client: HttpClient) {

        client.websocket(8080, "localhost", "/eventbus/websocket", { ws ->
            var timerId: Long = 0
            println("Connected!")
            //simulate vertx eventbus on SockJS endpoint
            val reg = JsonObject().put("type", "register").put("address", "news-feed")
            ws.writeFrame(WebSocketFrame.textFrame(reg.encode(), true))

            ws.handler({ buff ->
                //do the actual task here ...
                println(buff)

            })

            ws.closeHandler({
                println("Cancelling ping timer ...")
                vertx.cancelTimer(timerId)
            })

            //ping to keep the connection open ...
            timerId = vertx.setPeriodic(5000) { t ->
                ws.writeTextMessage("{\"type\":\"ping\"}")
            }
        }, { failureHandler ->
            println("ERROR: Unable to connect to websocket: " + failureHandler.message)

            vertx.setTimer(1000, {
                openWebSocketConnection(client) //recursive baby ...
            })
        })
    }
}