svelte-websocket-stores
v1.1.6
Published
Synchronize primitive-typed Svelte stores across a simple WebSocket connection.
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svelte-websocket-stores
Synchronize primitive-typed Svelte stores across a simple WebSocket connection.
Purpose
This was originally designed to allow touch panels to use Svelte with any backend.
Usage
Initialization
import { WebSocketWrapper } from "svelte-websocket-stores/websocket"
export const sws: WebSocketWrapper = new WebSocketWrapper({
server_address: "192.168.0.64",
server_port: 80,
local_scope: "tp1"
});
sws.start();
Write-only example
<script>
import { sws } from "main.ts";
let pressStore = sws.booleans.get("myCoolButton.press");
function press() {
$pressStore = true;
}
function release() {
$pressStore = false;
}
</script>
<button
on:pointerdown={press}
on:pointerup={release}
on:pointerout={release}>
<slot />
</button>
Read-only exmaple
<script>
import { sws } from "main.ts";
let sizeStore = sws.numbers.get("myList.size");
</script>
<div>
{#each { length: $sizeStore } as _, index}
<slot />
{/each}
</div>
WebSocket Message Format
All communication between a server and this library is over WebSocket.
All WebSocket messages are interpreted as JSON objects.
The message object is defined as:
type Message = {
scope: string,
id: string,
type: "boolean" | "number" | "string" | "object",
value: boolean | number | string | object,
}
The field scope
identifies the scope of the client it comes from and limits which clients receive it when coming from the server.
The field type
determines how the value
field is interpreted as well as which of the tables (booleans, numbers, strings, or objects) the id
field will be indexing into.
Client
Message Received
- The incoming text data is parsed as JSON.
- The object's
scope
field is checked if it is global ("global") or matches the client's local scope (for example "tp1"). If it does not match, the message is discarded. - The object's
type
field is switched on with the cases"boolean"
,"number"
,"string"
, and"object"
. If there is no match, the message is discarded. - The local Svelte store is indexed by the object's
id
field from the dictionary holding the respectively typed stores. - The store's value is assigned to the object's
value
field, cast to its respective type.
Server [^1]
Client Connected
- Send the client messages for all the variables currently stored values
Message Received
- The incoming text data is parsed as JSON.
- The object's
type
field is switched on with the cases"boolean"
,"number"
,"string"
, and"object"
. If there is no match, the message is discarded. - The variable is indexed by the object's
scope
andid
fields from the dictionary holding the respectively typed variables. - The variable's value is assigned to the object's
value
field, cast to its respective type. - Send all clients a message for the new value.
- Handle any events.
[^1]: This is the behavior expected by this WebSocket client