Websockets

Iris has a trivial way of registering websocket events via a Go structure. The websocket controller is part of the MVC features.

Iris has its own iris/mvc/Application.HandleWebsocket(v interface{}) *neffos.Struct to register controllers in existing Iris MVC applications(offering a fully featured dependency injection container for request values and static services).

// HandleWebsocket handles a websocket specific controller.
// Its exported methods are the events.
// If a "Namespace" field or method exists then namespace is set,
// otherwise empty namespace will be used for this controller.
//
// Note that a websocket controller is registered and ran under
// a connection connected to a namespace
// and it cannot send HTTP responses on that state.
// However all static and dynamic dependencies behave as expected.
func (*mvc.Application) HandleWebsocket(controller interface{}) *neffos.Struct

Let's see a usage example, we want to bind the OnNamespaceConnected, OnNamespaceDisconnect built-in events and a custom "OnChat" event with our controller's methods.

1. We create the controller by declaring a NSConn type field as stateless and write the methods we need.

type websocketController struct {
    *neffos.NSConn `stateless:"true"`
    Namespace string

    Logger MyLoggerInterface
}

func (c *websocketController) OnNamespaceConnected(msg neffos.Message) error {
    return nil
}

func (c *websocketController) OnNamespaceDisconnect(msg neffos.Message) error {
    return nil
}

func (c *websocketController) OnChat(msg neffos.Message) error {
    return nil
}

Iris is smart enough to catch the Namespace string struct field to use it to register the controller's methods as events for that namespace, alternatively you can create a controller method of Namespace() string { return "default" } or use the HandleWebsocket's return value to .SetNamespace("default"), it's up to you.

2. We inititalize our MVC application targets to a websocket endpoint, as we used to do with regular HTTP Controllers for HTTP routes.

import (
    // [...]
    "github.com/kataras/iris/v12/mvc"
)
// [app := iris.New...]

mvcApp := mvc.New(app.Party("/websocket_endpoint"))

3. We register our dependencies, if any.

mvcApp.Register(
    &prefixedLogger{prefix: "DEV"},
)

4. We register one or more websocket controllers, each websocket controller maps to one namespace (just one is enough, as in most of the cases you don't need more, but that depends on your app's needs and requirements).

mvcApp.HandleWebsocket(&websocketController{Namespace: "default"})

5. Next, we continue by mapping the mvc application as a connection handler to a websocket server (you may use more than one mvc applications per websocket server via neffos.JoinConnHandlers(mvcApp1, mvcApp2)).

websocketServer := neffos.New(websocket.DefaultGorillaUpgrader, mvcApp)

6. And the last step is to register that server to our endpoint through a normal .Get method.

mvcApp.Router.Get("/", websocket.Handler(websocketServer))