WebSockets

Video Course on Real-Time HTML5 with Node.jsnobody does WebSockets directly without a facade, but use frameworks e.g. socket.io or pusherajax is a roundtrip

there's an overhead for client initiating a request, the server a response and http packerts have extra 200 or more bytes

ajax is only when you need updates every 5 minutes, but not when 5 request per second (e.g. games)

in average an ajax request is about 500 - 800ms roundtrip

in websocket, there's an inital socket opening, then in either direction the header is 8 bytes, we don't pay the penalty to open and close connection

the latency is 50 - 100 ms

but even 100ms can be too slow in fact

"real-time" is a misnomer : it's sub microsecond or nanosecond

we mean "near real-time"

it's more resource intensive for the server: you need so many ports open

but in general it uses less bandwidth

the pattern is same for client or server. in general

socket.on("eventname" function(data){

self.postMessage({error: "game_session_invalid"});

});

and

socket.emit("another_event_name", {game_session_id: bar});

client and server can listen to send events (emit) and send data (JS objects) along

in addition the server can broadcast a message to all clients (it doesn't exist on the client)

Abundancia