How to deal with HTTP caching and ETag in PHP backend API development

With the development of the Internet, the development method of front-end and back-end separation is becoming more and more popular. In this case, the front end usually obtains data through HTTP requests to the API provided by the backend. However, the data acquisition speed of the API directly affects the front-end rendering speed and user experience. Therefore, in the API development process, it is particularly important to optimize the response speed of the interface. Among them, HTTP caching and ETag technology are two commonly used optimization methods.

1. HTTP Caching

Currently, HTTP requests are the most common method of data transmission on the Internet, and HTTP caching is the most basic method to optimize HTTP requests. By using HTTP caching, you can reduce the amount of data transmission between the client and the server, reduce the request response time, and improve the performance of the website.

The implementation mechanism of HTTP caching is very simple: on the first request, the server will save the response content in the client's cache. On the next request, the client will first check whether it exists in its cache. The response to this request, if it exists, returns the response in the cache directly without requesting the server again.

The specific implementation of HTTP caching is mainly achieved by setting the header of the response message. Usually, the Expires and Cache-Control fields are used for setting.

1. Epires

The Expires field is used to set the expiration time of the response. For example, Expires: Wed, 13 Jan 2021 22:23:01 GMT means that the server's cache will expire after January 13, 2021 22:23:01 GMT. After expiration, the client will send it to the server again. ask.

2. Cache-Control

Cache-Control is used to set specific cache strategies. Common setting parameters include max-age and no-cache. Among them, max-age is used to set the cache validity period in seconds. For example, Cache-Control: max-age=300 means that the cache will expire 300 seconds after the request is sent, while no-cache means that the client must send a request to the server, but the server will tell the client that the request The response can be cached.

However, for some frequently changing data, using HTTP caching is not necessarily a good idea. Because even if the cache is set, data changes on the server side may make it invalid. At this time, you need to use ETag technology.

2. ETag

ETag is a technology similar to file fingerprinting. It usually adds an ETag field to the header of the response message to identify the uniqueness of the response content. Each time the client requests, the last ETag value will be sent to the server for verification through the If-None-Match field. If the ETag value returned by the server is the same as the last time, it indicates that the data in the cache is the latest and the client can directly use the data in the cache. Otherwise, the client needs to re-request the server to obtain the latest data.

The advantage of using ETag technology is that it can handle frequent changes in data and avoid unnecessary data transmission. However, it should be noted that ETag does not apply to all situations. If the ETag value is set in the request header, but the data does not actually change, some computing resources of the server will be wasted.

Summary

HTTP caching and ETag are common API performance optimization methods, which can effectively reduce request response time and data transmission volume, and improve user experience. HTTP caching and ETag technology can be implemented by setting the header of the response message. Among them, the appropriate strategy should be selected according to the actual situation.

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