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Today, I will talk to you about the role of Web caching, which may not be well understood by many people. in order to make you understand better, the editor has summarized the following for you. I hope you can get something from this article.

What is Web caching

Web cache refers to a copy of a Web resource (such as html pages, images, js, data, etc.) that exists between the Web server and the client (browser). The browser will download the page again only when the site clearly identifies that the resource has been updated.

The role of Web caching

The effect of using Web caching is actually quite obvious:

Reduce network bandwidth consumption: for both website operators and users, bandwidth represents money, and excessive bandwidth consumption will only make network operators cheaper. When the Web cache copy is used, only a very small amount of network traffic will be generated, which can effectively reduce operating costs.

Reduce the pressure on the server: after setting the validity period for the network resources, users can reuse the local cache, reduce the request to the source server, and indirectly reduce the pressure on the server. At the same time, the crawler robot of the search engine can also reduce the crawling frequency according to the expiration mechanism and effectively reduce the pressure on the server.

Reduce network latency and speed up page opening: bandwidth is very important for personal website operators, while for large Internet companies, they may not really care because they have a lot of money. Does the Web cache still work? The answer is yes, for end users, the use of caching can significantly speed up page opening and achieve a better experience.

Type of Web cach

In the field of Web applications, Web caches can be roughly divided into the following types:

Database data caching: Web applications, especially SNS applications, often have complex relationships and numerous database tables. If you query the database frequently, it is easy to cause the database to be overloaded. In order to provide the performance of the query, the data after the query will be cached in memory, and the next query will be returned directly from the memory cache to provide response efficiency. For example, the commonly used cache schemes are memcached and so on.

Browser-side caching: the browser cache works according to a set of rules agreed with the server and checks once during the same session to make sure that the cached copy is new enough. If you access the same image during browsing, such as forward or backward, the images can be called up from the browser cache and displayed instantly.

Server-side cache

Proxy server cache: the proxy server is the intermediate server between the browser and the source server. The browser first initiates a Web request to this intermediate server, and then forwards the request to the source server after processing (such as permission verification, cache matching, etc.). Proxy server caching works in much the same way as browsers, but on a larger scale. It can be understood as a shared cache, serving not only one user, but also a large number of users, so it is effective in reducing the use of time and bandwidth, and the same copy will be reused multiple times. Common proxy server caching solutions include Squid and so on, which are not detailed here.

CDN cache: CDN (Content delivery networks) cache, also known as gateway cache, reverse proxy cache. CDN caching is generally deployed by webmasters themselves to make their sites easier to scale and achieve better performance. The browser first initiates a Web request to the CDN gateway, and the gateway server is followed by one or more load balancing source servers, which will dynamically forward the request to the appropriate source server according to their load requests. Although this architecture load balancing caches between source servers cannot be shared, it has better scalability. From a browser perspective, the entire CDN is a source server. From this level, this article discusses the caching mechanism between the browser and the server, which is also applicable in this architecture.

Web application layer caching: application layer caching refers to caching data, pages, pictures and other resources from the code level through code logic and caching strategy. You can choose to store the data in the file system or memory according to the actual situation, reduce database queries or read and write bottlenecks, and improve response efficiency.

After reading the above, do you have any further understanding of the role of Web caching? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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