What steps does a PHP request go through?

As a widely used programming language, PHP’s mechanism and operating process have always been what we need to pay attention to and learn. Among them, the steps a request goes through are issues that are often concerned during development. This article will introduce the steps a PHP request goes through, so that readers can have a comprehensive understanding of PHP's operating process.

1. The basic composition of a request

Before the specific explanation, let’s first understand the basic composition of a request. A PHP request contains at least the following three parts:

1. The client sends a request (the browser accesses the Web server)
2. The server accepts the request and processes the request through the PHP interpreter
3 .The server returns results (HTML, pictures, music or other format files)

Based on the above composition, we divide it into the following four steps to understand the running process of the PHP request.

2. The server receives the request

Before officially starting to process the PHP request, the server must first receive the request. Generally speaking, the server uses port 80 to receive HTTP requests by default. After receiving the request, the server will generate and record the overall information of the request (such as request time, request method, IP address, etc.). The purpose of generating this information is to facilitate statistical analysis, logging and website debugging.

3. Request distribution

After the server receives the request, we will start request distribution. According to the specific request, we can divide the request into the following two types:

1. Static request: refers to the server directly returning the content of the file when the user requests a file, without additional processing, calculation or Inquiry etc.

2. Dynamic request: When the user requests a file composed of PHP code, the server needs to process the PHP code in the file through the PHP interpreter, generate dynamic content and return it to the user.

For static requests, the server can directly return the requested file content, while for dynamic requests, the server will forward the request to the PHP processor (PHP interpreter) for processing.

4. PHP processor handles requests

After the server forwards the dynamic request to the PHP interpreter, the PHP interpreter will respond to the request based on the rules of the PHP code. We can divide the PHP processor process into the following stages:

1. Top-level code analysis: Analyze top-level code (such as function calls) to ensure the correctness of the code.

2. Compile: Compile the PHP code into binary code, that is, OPCODE.

3. Execution: Execute the compiled OPCODE to generate dynamic content.

4. Return results: Return the dynamic content obtained by execution to the server, and the server returns it to the client browser.

It should be pointed out that the PHP runtime will do some internal initialization work and establish some global variables and internal methods when each PHP file starts executing. So, once PHP starts executing the script, there is bound to be some time overhead. If the script simply generates some static HTML content, this time overhead is wasted.

5. The server responds to the request

After the PHP processor returns the generated dynamic content to the server, the server transmits the content to the user's browser via the network. After the user's browser receives the content, it can render the page effect.

6. Summary

The above is the main process of PHP processing a request and the details of the entire process. The author hopes that this article can give everyone a comprehensive understanding of the request processing process. At the same time, it is recommended that you avoid or minimize unnecessary memory allocation when developing PHP applications to improve performance and efficiency, so as to better satisfy users. need.

The above is the detailed content of What steps does a PHP request go through?. For more information, please follow other related articles on the PHP Chinese website!