velox
Real-time JS object synchronisation over SSE and WebSockets in Go and JavaScript (Node.js and browser)
Features
- Simple API
- Synchronise any JSON marshallable struct in Go
- Synchronise any JSON stringifiable struct in Node
- Delta updates using JSONPatch (RFC6902)
- Supports Server-Sent Events (EventSource) and WebSockets
- SSE client-side poly-fill to fallback to long-polling in older browsers (IE8+).
- Implement delta queries (return all results, then incrementally return changes)
Quick Usage
Server (Go)
//syncable struct
type Foo struct {
velox.State
A, B int
}
foo := &Foo{}
//serve velox.js client library (assets/dist/velox.min.js)
http.Handle("/velox.js", velox.JS)
//serve velox sync endpoint for foo
http.Handle("/sync", velox.SyncHandler(foo))
//make changes
foo.A = 42
foo.B = 21
//push to client
foo.Push()
Server (Node)
//syncable object
let foo = {
a: 1,
b: 2
};
//express server
let app = express();
//serve velox.js client library (assets/dist/velox.min.js)
app.get("/velox.js", velox.JS);
//serve velox sync endpoint for foo (adds $push method)
app.get("/sync", velox.handle(foo));
//make changes
foo.a = 42;
foo.b = 21;
//push to client
foo.$push();
Client (Node and Browser)
// load script /velox.js
var foo = {};
var v = velox("/sync", foo);
v.onupdate = function() {
//foo.A === 42 and foo.B === 21
};
API
Server API (Go)
Server API (Node)
velox.handle(object)function returnsv- Creates a new route handler for use with expressvelox.state(object)function returnsstate- Creates or restores a velox state from a given objectstate.handle(req, res)function returnsPromise- Handle the providedexpressrequest/response. Resolves on connection close. Rejects on any error.
Client API (Node and Browser)
velox(url, object)function returnsv- Creates a new SSE velox connectionvelox.sse(url, object)function returnsv- Creates a new SSE velox connectionvelox.ws(url, object)function returnsv- Creates a new WS velox connectionv.onupdate(object)function - Called when a server push is receivedv.onerror(err)function - Called when a connection error occursv.onconnect()function - Called when the connection is openedv.ondisconnect()function - Called when the connection is closedv.onchange(bool)function - Called when the connection is opened or closedv.connectedbool - Denotes whether the connection is currently openv.wsbool - Denotes whether the connection is in web sockets modev.ssebool - Denotes whether the connection is in server-sent events mode
Example
See this simple example/ and view it live here: https://velox.jpillora.com
Here is a screenshot from this example page, showing the messages arriving as either a full replacement of the object or just a delta. The server will send which ever is smaller.
Notes
-
JS object properties beginning with
$will be ignored to play nice with Angular. -
JS object with an
$applyfunction will automatically be called on each update to play nice with Angular. -
velox.SyncHandleris just a small wrapper aroundvelox.Sync:```go func SyncHandler(gostruct interface{}) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if conn, err := Sync(gostruct, w, r); err == nil { conn.Wait() } }) } ```
Known issues
- Object synchronization is currently one way (server to client) only.
- Object diff has not been optimized. It is a simple property-by-property comparison.
TODO
- WebRTC support
- Plain
httpserver support in Node - WebSockets support in Node
MIT License
Copyright © 2018 Jaime Pillora <dev@jpillora.com>
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.