Explore the causes and solutions for repeated HTTP status code requests

Understand the reasons and solutions for HTTP status code requests twice

Abstract: HTTP status code is an important response identifier in the communication process between the client and the server . When using the HTTP protocol for network communication, we often encounter the situation of requesting twice. This situation not only increases the network burden, but may also lead to redundant transmission of data. This article will explore the reasons for requesting twice and explore how to fix the problem.

1. Introduction

HTTP status code is a mechanism to identify the server response result. It classifies and describes the request result through a three-digit number. Common status codes include 200 (request successful), 404 (requested resource not found), and 500 (server internal error).

However, sometimes we find that when using the HTTP protocol for network communication, there will be two requests, that is, after sending one request, the server will receive two requests. This situation is often thought to be a problem with the network transmission, but there may actually be other causes.

2. The reason for requesting twice

2.1 Browser preloading

In order to improve the user experience, modern browsers often perform page preloading. When a user visits a web page, the browser will preload other web pages that may be clicked by the user based on a certain algorithm. In this way, when the user actually clicks the link, the browser has already obtained the page content in advance and sent the request. Therefore, two requests may appear in the network monitoring tool.

2.2 Redirect

Redirect is a common server behavior. When a server cannot handle a request, it often redirects the request to another appropriate page. During the redirection process, the browser will send a request to the new target address, resulting in multiple requests.

2.3 Cache Invalidation

The caching mechanism is used between the browser and the server to reduce network transmission volume and improve performance. When the browser cannot find the required content in the cache, it will send a request to the server again to obtain the latest data. This situation may result in duplicate requests.

3. Solution

3.1 Control browser preloading

For the repeated request problem caused by browser preloading, we can control the browser's Preload behavior to solve. This can be achieved by adding the following code to the header tag of the web page:

<meta http-equiv="x-dns-prefetch-control" content="off">

This will disable the browser's preloading function and reduce unnecessary requests.

3.2 Properly set up the cache

Properly set up the cache mechanism can effectively reduce the repeated sending of requests. By setting appropriate expiration time and ETag and other identifiers, the browser can directly obtain data from the cache within a period of time to avoid multiple requests.

3.3 Using POST request

Compared with GET request, POST request is not easy to be cached. If you can use POST requests instead of GET requests, you can reduce the number of requests the server receives. Of course, you need to pay attention to the rationality and security of the request when using POST requests.

4. Conclusion

HTTP status code is an important identifier in the communication process between the client and the server. Understanding the reason for requesting twice can help us resolve this issue. By controlling browser preloading, setting cache appropriately, and using POST requests, we can effectively reduce the network burden and redundant data transmission caused by repeated requests.

Requesting twice may be caused by browser preloading, redirection, cache failure, etc. For different reasons, we can adopt different solutions, such as controlling browser preloading, setting cache appropriately and using POST requests. Through reasonable control and optimization, we can improve the efficiency and performance of network communication.

5. References

[1] Terse, R. (2020). Why might HTTP requests double?. Retrieved from https://stackoverflow.com/questions/ 5970734/why-might-http-requests-double

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