Amber <> Squeak communication using websockets, round 2

  Hi, a while back I tried using websockets to work with squeak, pharo
and amber, with some limited success.  I can't remember exactly why I
gave up on the idea, but for some reason it didn't work out for me.  I
posted on the newsgroup about my efforts.

  Well, I noticed a forum post from world.st in which WebClient and
WebServer were updated for squeak to use more modern websocket
protocols.  I decided to try them again.  I now have a fully
functional multiplayer game demo coded in amber in client and squeak
for server.  Using this solution I don't think you need to host amber
in any special way - you don't need to host it in node and you don't
need to use the recent one click solution.  Just serve your client
files via apache or whatever, and have a running squeak image on the
same domain (if it's not on the same domain it won't work because of
cross site scripting security blocks on all major browsers).

  First off, let me say that if you try this - you're probably better
off using squeak instead of pharo.  The package WebClient is made for
squeak, and I had trouble getting the pharo version to work in the
past and recently as well.  If you want to try to get it to work in
pharo, you'll need to figure out how to install 'Installer' first, (I
tried installing it and it crashed my image).

  To get this whole thing to work, get squeak and install the latest
WebClient package (it supports websockets and comes with WebServer
class as well).  In amber no special libraries are necessary, at least
on chrome.  (It should work in firefox and other major browsers as
well).

  Once you've got your squeak image running, it's a simple matter of
using standard WebSocket object in amber/javascript and modifying the
WebSocket class >> example method in squeak.

  In case you have problems getting started, here is my cheat sheet
for useful methods on both sides:


  Amber:

<socket = new WebSocket("ws://www.zenchess.com:4003/broadcast");>.

^^ modify the above code to point to your web domain and the port that
WebSocket example is running on.

<socket.onopen = function(){
    alert("Socket has been opened!");
        self._onOpen();
        }  >.

^^ There's the function you register with your socket object that gets
called when the socket is opened for the first time.  self._onOpen();
is javascript code that will call the onOpen method in the class that
it is running from.  This lets me write an onOpen method in complete
smalltalk.  I couldn't figure out how to convert the above javascript
code into the smalltalk equivalent, so that is why I am using the < >
's .


<socket.onmessage = function(msg){

        data = msg.data;>.


Hopefully the above code and explanation can help anyone that is
looking for amber>regular smalltalk image communication.  I know there
are other solutions but websocket is actually a really good one, since
it's 2-way and does not have to continuously poll to get updates.  By
the way there are some JSON convenience methods for decoding and
encoding JSON in squeak in the WebUtils package of WebClient that came
in handy as well.

  I've been coding a multiplayer turn based strategy game in Ludus/
Amber/Squeak and it's coming along nicely, I'll be sure to demo it
here first. :P

On 20/02/12 06:55, Zenchess wrote:


Did you know you can that in Smalltalk:

>    Amber:
>
> <socket = new WebSocket("ws://www.zenchess.com:4003/broadcast");>.

socket := WebSocket new value: 'ws://www.zenchess.com:4003/broadcast'.

>
> ^^ modify the above code to point to your web domain and the port that
> WebSocket example is running on.
>
> <socket.onopen = function(){
>     alert("Socket has been opened!");
> self._onOpen();
> }>.
>


socket onopen: [
        window alert: 'socket open'.
        self onOpen]

>
> <socket.onmessage = function(msg){
>
> data = msg.data;>.

socket onmessage: [:msg | data := mdg data]


Cheers,
Nico


--
Nicolas Petton
http://nicolas-petton.fr

Cool stuff! Welcome back!

  Hi Nicolas, I tried your version of the code, and got this:

"function WebSocket() { [native code] } does not understand #new"


On Feb 20, 3:50 am, Nicolas Petton <[hidden email]> wrote:

  I'm almost finished making the game, so I'd like to finish that
first.


> Cool stuff! Welcome back!
>
> Can we get a URL to your demo app to take a look at it?
>
> Cheers,
>

On 22/02/12 09:45, Zenchess wrote:
>    Hi Nicolas, I tried your version of the code, and got this:
>
> "function WebSocket() { [native code] } does not understand #new"


Yeah, there's an error in the code I wrote. It should be:
socket := WebSocket newValue: 'ws://www.zenchess.com:4003/broadcast'

But anyway WebSocket isn't a normal function, so it doesn't seem to work
in this particular case :/

Cheers,
Nico


--
Nicolas Petton
http://nicolas-petton.fr

Congratulations. Looking forward to play a game.

On 22 Feb., 11:38, Nicolas Petton <[hidden email]> wrote:
I get an error on Chrome 12.0 and FF 10.0 saying:

  function WebSocket() { [native code] } does not understand
#newValue:"

Regards...