如何在PHP中创建websockets服务器？

Question

I have been searching the internet for about two days now, trying to understand how web sockets work, I am relatively new at Javascript and PHP, seeing as I started about two or three months ago.

I am extremely confused about what an Http protocol is, and how to perform a 'handshake' with a server as I have been reading about. So unfortunately it is difficult for me to ask a more specific question than the one in the title.

However, even more than I would like an answer to the question in the title, I would really like a resource that will teach me about web sockets in a thorough way, such as a book or an online tutorial.

Any help is appreciated, thanks.

Answer 1

Sockets in general are just TCP streams that you can send data over. HTTP is built on top of them. WebSockets are build on/in parallel with HTTP, and allow for sending data back and forth to a browser in real-time. Standard sockets can do some of this, but browsers have tight security which makes it tough to use standard sockets to communicate with them.

WebSockets are useful when you need a persistent connection to the server from the browser, for real-time applications, or things like push notifications.

I don't know much about PHP implementations unfortunately, but it looks like there is a library here: http://code.google.com/p/phpwebsocket/

Personally, I'd shy away from doing things like this in PHP because PHP/Apache can be pretty heavy, and since the socket is always open while someone is viewing the page, server resources can be used up pretty quickly.

A lot of people like to use NodeJS with socket.io because then you can use JavaScript on the server and the browser, but really it is up to preference. I would look at Socket.IO and find a language that has a good client for it.

It looks like this question might be useful too. Using PHP with Socket.io