The HEAD of the HTTP request method

The HTTP request method is not only get and post, but is most commonly used. According to the RFC2616 standard (current http/1.1), there are usually the following 8 ways:options,GET,HEAD, POST, PUT, DELETE, Trace and connect.

Official definition

The head method is the same as the Get method, except that the message body is not returned by the server response. In response to a head request, the HTTP header contains the same meta information as the response message for a GET request. This method can be used to get the meta information that is implied in the request without transmitting the entity itself. It is also often used to test the validity, usability, and recent modification of hyperlinks.

A HEAD request response can be cached, that is, the information in the response may be used to update the previously cached entity. If the current entity is different from the threshold of the cache entity (which can be indicated by changes in Content-length, CONTENT-MD5, ETag, or last-modified), then the cache is considered expired.

Nutshell

Head requests are often overlooked, but can provide a lot of useful information, especially at limited speeds and bandwidth. The main features are as follows:

1, only the first request for resources;

2, check the validity of hyperlinks;

3, check whether the webpage is modified;

4, more for automatic search robot to obtain Web page logo information, access to RSS seed information, or transmission of security certification information, etc.

The HEAD of the HTTP request method