Lightweight Real-time Ajax, WebSocket, or Similar for Scala

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Our requirements for a real-time web framework include:

  • lightweight framework
  • scala support on server side
  • flexible on communication mechanism : may be Ajax, Server Sent Event or WebSocket.
  • relatively little changes required to client html.
    • E.g. using the WebSockets js library is fine
    • introducing significant compile time/server side page processing is not. E.g. Play routing annotations are not acceptable
  • must have working examples for both:
    • web clients
    • server to server communications
    • fully functional build. Preferably sbt, but maven maybe acceptable

I have evaluated the following frameworks: and each one of them has one or more drawbacks that make usage within our application less than desirable.

  • Play: somewhat heavy, but more importantly it introduces custom annotations/processing into the html page. We need VANILLA html pages.

  • Spray: closer to the mark. But although I found a number of example applications, the actor-based communication is not working in those examples. The SimpleServer example has a built-in "cases" counter (from SimpleClient) that do not work as given: they could certainly be made to work .. eventually..

  • atmosphere: lacking examples

    • jetty, netty: lacked fully functional examples buildable within sbt or maven

  • socko : The markdown essentially stipulates using eclipse/scala-IDE for running tests/doing development. That is a non-starter for us (IJ shop). It was unclear how to run examples and/or start their servers from sbt / command line.

2
ajaxscalawebsocketweb-frameworks
Nothing prevents you from using vanilla HTML with Play. Spray does in fact work, despite your tests to the contrary. netty does have an obvious example buildable with sbt - the Play framework. - wingedsubmariner
@wingedsubmariner The examples for play that I found included routing annotations. If you have pointers to vanilla html/js (e.g using XmlHttpRequest or WebSocket Js library methods are just fine) please post as an answer and I would be inclined to accept. - WestCoastProjects
Can you elaborate on "actor-based communication is NOT working"? Spray uses actors extensively and we've had no problems in our projects. - Gangstead
@javadba Can you give more details as to why you don't want any special annotations in your html/js? As windegsubmariner said, nothing prevents you from using the complete urls instead of the routing annotations, but it just makes your code harder to maintain (because everytime you change an endpoint url, you have to remember to also change it in your html) - noziar
@noziar The html/client code will be consumed by very separate codebases, we want there to be no hint of the server side framework there. - WestCoastProjects

2 Answers

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I ended up writing a fair amount of custom code wrapped around Netty. After it is in better shape I may drop it on GitHub.

0
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http://xitrum-framework.github.io/ is actively developed and contains SocksJs support. It is rather lightweight, you can directly annotate routes on actors and they become exposed on the web.