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WLJSTransport

<<JerryI`Misc`WLJS`Transport`

WLJSTransportScript​

A helper function to set up a WebSocket connection to a server from a page. It should be placed and executed in the head section of a page

WLJSTransportScript[opts__] __String

There are several options

  • "Port" -> _Integer (required) specifies a port of WebSocket server
  • "Event" -> _String an string identifier of an arbitrary EventObject on a server. Once connection established it will fire an event with "Connected" topic or pattern.

Example​

In the header section of your page, put this line

<head>
	...
	<WLJSTransportScript Port={yourPort}/>
</head>

WLJSTransportHandler​

A handler function for WebSocketHandler transport, that evaluates the requests from an WL interpreter running on client's side and provides features of symbols tracking.

WLJSTransportHandler

an entry point for evaluation requests, connect it to your chain of handlers as follows

ws = WebSocketHandler[]
ws["MessageHandler", "Evaluate"] = Function[True] -> WLJSTransportHandler

Symbols tracking​

To use this feature one need to specify a few more down-values

WLJSTransportHandler["AddTracking"] = Function[{symbol, name, cli, callback},
    Print["Add tracking... for "<>name];
    Experimental`ValueFunction[Unevaluated[symbol]] = Function[{y,x}, callback[cli, x]];
, HoldFirst]

WLJSTransportHandler["GetSymbol"] = Function[{expr, client, callback},
    Print["Evaluating the desired symbol on the Kernel"];
    callback[expr // ReleaseHold];
]

After that you can freely use Offload to dynamically bind symbols from server to pages.

$Client​

A global object, that specifies a connected client

WLJSTransportSend​

Submits an arbitrary WL expression to WL interpreter running in a browser using WebSockets

WLJSTransportSend[expr_, client_] _

A set of expression possible to be evaluated depends on WLJS Interpreter, its imported libraries and defined function on a page as well.

An identifier of a client can be retrieved using global symbol $Client in the context of fired "Connected" (see WLJSTransportScript Event) event or other events from buttons or other UI elements.

Example​

Once you know a connected client using $Client try to evaluate

WLJSTransportSend[Alert["Hello World"], client]

Offload​

A key-expression with HoldFirst attribute, that holds an expression to be interpreted on browser's side

Offload[expr_] _

Usually comes handy with automatic symbol binding between server and client, since an unknown symbol for a client is requested from server and then, interpreter subscribes for any changes of it.

Example​

Prepare your page and server as its shown in guide dynamics, attach symbols tracking as mentioned in WLJSTransportHandler and then

App.wlx
pts = {{0,0}};
Graph = Graphics[Point[Offload @ pts], PlotRange -> {{-1,1}, {-1,1}}];

task = SessionSubmit[ScheduledTask[pts = Append[pts, Last[pts] + 0.25 RandomReal[{-1,1}, 2]], Quantity[0.3, "Seconds"]]];

<div class="mx-auto max-w-7xl py-6 sm:px-6 lg:px-8">
    <WLJS><Graph/></WLJS>
</div>
caution

Created task will continue to run in the background. One need to detect closed connection and remove in manually. See tutorials.

server​

A global Javascript object that represents server and created by WLJSTransportScript There are several methods available for communication

.socket​

A connected WebSocket object

.send(message)​

Send a message for evaluation (async)

server.send('Echo["Hi from sockets!"]')

.emitt(uid, message, topic='Default')​

Emits an event on server's side with a given string identifier of EventObject. To capture an event one have to subscribe to it using

server.emitt('uid', '1+1', 'Topic');

and on server's side

EventHandler["uid", {"Topic" -> Function[data,
	Print[data];
]}]

or an omni listener

EventHandler["uid", Function[data,
	Print[data];
]]

.ask(message)​

Asynchronously evaluates a message on a server and returns Promise object

const data = await server.ask('RandomReal[{-1,1}, 100]');
const result = await interpretate(data, {});
console.log(result);
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