Shulou(Shulou.com)06/02 Report--

This article is about how PHP can improve the performance of the website. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

* to minimize the number of HTTP requests (Make Fewer HTTP Requests)

Http requests are expensive, so finding ways to reduce the number of requests can naturally improve the speed of web pages. The common method is to merge css,js (merging css and js files in a page separately), Image maps and css sprites, etc. Of course, perhaps the css,js file will be split into multiple because of css structure, sharing and other considerations. The practice of Alibaba Chinese site at that time was to develop separately during development, and then merge js,css in the background, which is still a request for the browser, but it can still be restored to multiple during development, which is easy to manage and repeat references. Yahoo even recommends that the css and js of the front page be written directly in the page file instead of external references. Because the number of visits to the home page is too large, this can also reduce the number of requests by two. In fact, many domestic portals do so.

Css sprites refers to simply merging the background image on the page into one, and then fetching his background through the value defined by the background-position attribute of css. Both Taobao and Alibaba Chinese stations currently do this. Those who are interested can take a look at the background pictures of Taobao and Alibaba.

Http://www.csssprites.com/ this is a tool website, it can automatically merge your uploaded images and give the corresponding background-position coordinates. The results are output in png and gif formats.

Second, use CDN (content delivery Network): Use a Content Delivery Network

To tell you the truth, I don't know much about CDN. To put it simply, by adding a new network architecture to the existing Internet, publishing the content of the website to the cache server closest to the user, and through the DNS load balancing technology, we can determine that the user source visits the cache server nearby to get the required content, the user in Hangzhou visits the content on the server near Hangzhou, and the user in Beijing accesses the content on the server near Beijing. This can effectively reduce the time of data transmission on the network and improve the speed. For more details, you can refer to the explanation of CDN on Baidu encyclopedia. Yahoo! Distributing static content to CDN reduces user impact time by 20% or more.

Third, add Expire/Cache-Control header: Add an Expires Header

Now that more and more images, scripts, and css,flash are embedded in the page, we are bound to make many http requests when we visit them. In fact, we can cache these files by setting Expires header. Expire actually specifies how long a particular type of file will be cached in the browser through a header message. For most of the pictures, flash does not need to be modified frequently after it is released. After caching, the browser will no longer need to download these files from the server but read them directly from the cache, so that the speed of accessing the page again will be greatly accelerated. Header information returned by a typical HTTP 1.1 protocol:

HTTP/1.1 200 OK Date: Fri, 30 Oct 1998 13:19:41 GMT Server: Apache/1.3.3 (Unix) Cache-Control: max-age=3600, must-revalidate Expires: Fri, 30 Oct 1998 14:19:41 GMT Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT ETag: "3e86-410-3596fbbc" Content-Length: 1040 Content-Type: text/html

This can be done by setting up Cache-Control and Expires through server-side scripts.

For example, it expires 30 days after setting it in php

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