Stocking

[WIP] Minimal Websocket Framework with Server(Go) and Client(Javascript)

This is the server-side repository. For the client part, please visit WIP.

Status

Unstable - DO NOT USE IN PRODUCTION

The library is right now under early-stage development for experiment only. APIs may vary at any time.

Installation

go get github.com/afterwind-io/stocking

Documentation

• [WIP]APIs

Usage

package main

import "github.com/afterwind-io/stocking"

func main() {
  // Create a standalone server
  server := stocking.NewStocking("localhost:12345", "")

  // Setup routers
  server.On("echo", echo, nil)
  server.On("greet", greet, person{})
  server.Otherwise(otherwise)
  
  // Start serving on ws://localhost:12345/ws
  server.Start()
}

type person struct {
  Name string `json:"name"`
}

func echo(p stocking.RouterPackage) (interface{}, error) {
  return p.Body, nil
}

func greet(p stocking.RouterPackage) (interface{}, error) {
  body, _ := p.Body.(*person)

  if body.Name == "doge" {
    return "Hello " + body.Name, nil
  }

  return "Who are you?", nil
}

func otherwise(p stocking.RouterPackage) (interface{}, error) {
  return "oops", nil
}

Protocol

Structure

The client and the server communicates based on string formated as following:

[MessageType],[ControlCode],[Content]

eg: 4,0,{e: "echo", p: "doge"}

Client -> Server

MessageType	ControlCode	Payload	Brief
Connect	0	NONE	Initial connection (Not Implemented)
	1	NONE	Reconnection (Not Implemented)
Close	NONE	NONE	Close connection
PingPong	NONE	NONE	Start PingPong minigame ¯\(ツ)/¯
Message	0	(See Below)	Message without callback
	Int > 0	(See Below)	Message with callback indexed by CCode
Broadcast	String	Any	Broadcast to a channel/room named by CCode
Join	1	String	Join a channel/room
	0	String	Leave a channel/room

Server -> Client

MessageType	ControlCode	Payload	Brief
Connect	NONE	NONE	Connection confirm
Error	Int	String	Server error
Close	NONE	NONE	Close connection
PingPong	NONE	NONE	Start PingPong minigame ¯\(ツ)/¯
Message	Int > 0	(See Below)	Callback message indexed by CCode
Broadcast	String	Any	Channel/Room message from CCode

Message Type

// Message type when sent to server
type TextMessageProtocol struct {
  // The event name
  Event   string          `json:"e"`

  // Payload should be interface{} here.
  // json.RawMessage ensures that we can unmarshal it
  // to the actual type we need later.
  Payload json.RawMessage `json:"p"`
}

// Message type when sent to client through router
type RouterMessageProtocol struct {
  // Code indicates the error type.
  // -1 means no error;
  // 0 is the default error code;
  // You can put other value here by throwing a RouterError;
  Code    int         `json:"c"`

  // The Message body
  Payload interface{} `json:"p"`
}

More details see protocol.go

Middleware

Middleware design in Stocking is largely inspired by Koa. I managed to mimic similar syntax using goroute and channel. The following logger example shows how basic middleware looks like:

func (me *mLogger) Handle(p *HubPackge, next MiddlewareStepFunc) {
  // [Downstream Jobs] Do some inbound logs here
  log.Println(fmt.Sprintf("<-- [%v] %v, %v, %v", p.client.id, p.mtype, p.ack, p.content))

  // Temporarily suspended and pass the control to the next middleware
  done := <-next(nil)
  
  // Meanwhile downstream middlewares are doing their own jobs now

  // After they finished their jobs, the control flow rewinds,
  // and middlewares are resumed to perform its upstream jobs, in reverse order

  // [Upstream Jobs] Now grab outbound messages and log it
  log.Println(fmt.Sprintf("--> [%v] %v, %v, %v", p.client.id, p.mtype, p.ack, p.content))

  // duty ends here
  done <- nil
}

Roadmap

• At least it is kinda working
• Broadcast
• Channel
• Auto-Reconnect

Known Flaws

• If an error occurs and breaks the Read/Write loop, there's currently no graceful way to stop the other one. -> client.go
• If client route handler panics, the whole server just faint away :( -> mRouter.go
• Route handling stops the world. -> hub.go

Trivia

• Why name it "Stocking"?

  I'm a fan of white stocking Just put a "t" in "Sock". Besides, Christmas is coming.

License

MIT