From d3dabc94ad162289342c2adb8ae863b1260f8b77 Mon Sep 17 00:00:00 2001
From: Will Billingsley <wbilling@une.edu.au>
Date: Mon, 17 Sep 2018 20:21:54 +1000
Subject: [PATCH] Made one of the websocket examples more idiomatic
---
app/controllers/ExamplesController.scala | 52 +++++++++++++-----------
conf/routes | 4 +-
2 files changed, 31 insertions(+), 25 deletions(-)
diff --git a/app/controllers/ExamplesController.scala b/app/controllers/ExamplesController.scala
index 4f039c7..73a04e2 100644
--- a/app/controllers/ExamplesController.scala
+++ b/app/controllers/ExamplesController.scala
@@ -87,7 +87,7 @@ class ExamplesController @Inject()(cc: ControllerComponents)(implicit ec: Execut
*
* @return
*/
- def websocketWithHelper():WebSocket = {
+ def webSocketWithHelper():WebSocket = {
WebSocketHelper.createWebSocket[String, String](
{ queue =>
// We now have an asynchronous queue. What would we like to do with it
@@ -109,39 +109,44 @@ class ExamplesController @Inject()(cc: ControllerComponents)(implicit ec: Execut
* asynchronous work. However, using this template, you should just
* @return
*/
- def websocket() = WebSocket.accept[String, String] { request =>
-
- // Our source is going to be an asynchronous queue we can push messages to with 'out.offer(msg)'. This is going to
- // be the "source" of our flow. A complication is it doesn't create the queue immediately - this just says
- // *when* this source is connected to a flow, create a queue. So we don't have a queue yet.
- val outSource = Source.queue[String](50, OverflowStrategy.backpressure)
+ def webSocket() = WebSocket.accept[String, String] { request =>
// Because I want to refer to the queue in the sink, but I haven't actually got the queue yet, I'm just creating
// a box to put our queue in. At the moment, it's empty
var outOpt:Option[SourceQueueWithComplete[String]] = None
- // Create a "sink" that describes what we want to do with each message. Here, I'm just going to count the characters
- // and echo it straight back out on the "out" queue.
- val in = Sink.foreach[String] { message =>
+ // A websocket is made from a "flow" - a source of messages up to the browser, and a sink for messages from the browser.
+ // We're going to need to give this function our Sink and our Source as arguments.
+ Flow.fromSinkAndSourceCoupledMat(
- // If we have an out queue, send the message on it
- outOpt foreach { out =>
- out.offer(s"That message had ${message.length} characters in it")
- }
+ // Create a "sink" that describes what we want to do with each message. Here, I'm just going to count the characters
+ // and echo it straight back out on the "out" queue.
+ Sink.foreach[String] { message =>
- }
+ // If we have an out queue, send the message on it
+ outOpt foreach { out =>
+ out.offer(s"That message had ${message.length} characters in it")
+ }
+
+ },
- // This defines a "flow" -- something that has an input and an output.
- // "Coupled" means that if the input closes, the output will close
- // "Mat" means "materialised" -- ie, it'll give us the output queue that gets created and the Future that will
- // complete when the flow is done.
- Flow.fromSinkAndSourceCoupledMat(in, outSource) { case (done, out) =>
+ // Our source is going to be an asynchronous queue we can push messages to with 'out.offer(msg)'.
+ // The queue will be created when the connection is complete - this just says what it *will* be
+ Source.queue[String](50, OverflowStrategy.backpressure)
- // done is a future that will complete when the flow finishes
+ ) { case (done, queue) =>
+
+ // the second argument list is a callback that takes a tuple with two arguments.
+ // done is a future (like a JavaScript promise) that will complete when the flow finishes
// out is our "materialised" output queue. All we need do is put it in the box we made earlier
- out.offer("Connected!")
- outOpt = Some(out)
+ // Send a connected message to the browser
+ queue.offer("Connected!")
+
+ // Put the queue in the box we defined earlier
+ outOpt = Some(queue)
+
+ // When the connection has ended, empty the box and println that it's closed
done.foreach { _ =>
outOpt = None
println("Connection closed!")
@@ -149,6 +154,7 @@ class ExamplesController @Inject()(cc: ControllerComponents)(implicit ec: Execut
}
+
}
/**
diff --git a/conf/routes b/conf/routes
index 192f1c9..5af64d0 100644
--- a/conf/routes
+++ b/conf/routes
@@ -11,8 +11,8 @@ POST /example/json controllers.ExamplesController.receiveJsonPo
GET /example/game controllers.ExamplesController.game(id:Option[String])
-GET /example/socket controllers.ExamplesController.websocket()
-GET /example/time controllers.ExamplesController.websocketWithHelper()
+GET /example/socket controllers.ExamplesController.webSocket()
+GET /example/time controllers.ExamplesController.webSocketWithHelper()
GET /example/eventsource controllers.ExamplesController.eventSource()
--
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