Luckily for us, there are already some libraries that thought on that and offers their own WebSocket Server. Now that we have very “hacky” but stable way to make async calls on PHP - at least until Fibers come in PHP 8.1 at the end of the year - the next step is to hook into the socket server, and then upgrading the incoming HTTP Request connections to WebSockets connections, keeping them open in memory. That’s in a nutshell, as the details deserve a whole article on its own. The stream_socket_server function in PHP allows to create a socket that returns whatever connection goes in, as it works like a Generator, along stream_set_blocking set as non-blocking.Ĭouple that with an async library like ReactPHP or Amp, among the most used these days, and you can have a connection handler that doesn’t block the whole application while waiting for the next connection being made.

The thing is, PHP has everything it needs to work with WebSockets. ReactPHP will ask for the user to set a “driver”, while Amphp will use them automatically in that order. There is an interesting small book about generators and how these can work to make code asynchronous.įor those wanting performance, these libraries can “bypass” the Generator performance penalty and directly use libraries that control events themselves, like libuv, libevent and libev. This example is simple and will return “bar foo” if you run it. Just a simple approach to almost-async functions.

You can generate a loop over multiple “callables” registered inside a value that always returns the result of the callable in the stack: Generator are the key for Concurrency, a technique used in some programming languages, like Javascript. It’s like the Fiber less-friendly cousin. In a nutshell, Generators are functions that can iterate over an “unknown” and return values as these are received, by just simply pausing the function execution and waiting for the next value. Some time ago, some folks found that PHP could handle some sort of concurrency through using Generators. I’m always been very vocal about PHP being used for thing that is not suited for, like holding socket connections, when the nature of the language and the runtime itself is single-threaded, or “blocking” if you say.īut, even If I didn’t wanted to and looked into Go and Rust for the implementation, I figured out that WebSocket on PHP wasn’t THAT bad to work with, but there were a few caveats. One thing I had to implement against my will was a Websocket server… in PHP.

Php simple websocket