What is socket in php? Detailed explanation of socket examples

What is Socket?

Socket is an intermediate software abstraction layer that communicates between the application layer and the TCP/IP protocol suite. It is a set of interfaces. In the design mode, Socket is actually a facade mode, which hides the complex TCP/IP protocol family behind the Socket interface. For users, a set of simple interfaces is all, allowing Socket to organize data to meet the specified requirements. protocol. It has been rare to see many people using PHP’s socket module to do some things. Probably everyone places it within the scope of scripting languages, but in fact, PHP’s socket module can do many things, including doing ftplist , http post submission, smtp submission, group package and interaction of special messages (such as smpp protocol), whois query. These are some of the more common queries. Especially what PHP's socket extension library can do is not much worse than C.

Socket Basics

php uses Berkley's socket library to create its connections. You can know that socket is just a data structure. Use this socket data structure to start a session between the client and the server. This server is always listening and preparing to generate a new session. When a client connects to the server, it opens a port on which the server is listening for a session. At this time, the server accepts the client's connection request and then performs a cycle. Now the client can send information to the server, and the server can send information to the client.
To generate a Socket, three variables are required: A protocol, a socket type and a public protocol type. There are three protocols to choose from when generating a socket. Continue reading below to get detailed protocol content. Defining a public protocol type is an essential element of connection. Let's take a look at these common protocol types.

1. Protocol

2. Socket type

Knowing the three elements that generate a socket, then we use the socket_create() function in php to generate a socket. The socket_create() function requires three parameters: a protocol, a socket type, and a public protocol. The socket_create() function returns a resource type containing the socket if it runs successfully. If it fails, it returns false.

Resourece socket_create(int protocol, int socketType, int commonProtocol);

php provides several functions for manipulating sockets, which can bind the socket to an IP, monitor the communication of a socket, and accept a socket; now let's look at an example to understand how the function is generated , accept and listen to a socket.

The code is as follows:

<?php
$commonProtocol = getprotobyname("tcp");
$socket = socket_create(AF_INET, SOCK_STREAM,$commonProtocol);
socket_bind($socket,&#39;localhost&#39;,1337);
socket_listen($socket);
?>

Instructions: The above example generates your own server.

The first line of the example uses the public protocol name to obtain a protocol type. The TCP public protocol is used here. If you want to use UDP or ICMP protocol, then you should change the parameters of the getprotobyname() function to "udp" or "icmp". An alternative is to not use the getprotobyname() function but specify SOL_TCP or SOL_UDP in the socket_create() function.
The second line of the example generates a socket and returns an instance of the socket resource. After you have an instance of the socket resource, you must bind the socket to an IP address and a port.
The third line here binds the socket to the local computer (127.0.0.1) and binds the socket to your 1337 port. Then you need to listen for all incoming socket connections. After the fourth line, you need to understand all socket functions and their usage. The socket function will be explained in detail in later chapters.

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