Introduction to the WWW

Method in charge of delete a resource from the server. The resource could be a file, an entry on a database, or whatever. This method is not a default method, so should be implemented by the server.

The get method is used to ask for a resource from a serve. This method can’t send data to the server. The answer is a text which could be in different formats, like HTML, JSON and so on.

To make the request more specific, you can send some information about what you are looking up. This values are append to the URL, as a key value, separate each one with the ampersand & symbol and after the close question mark of the URL.

In most cases, is enough to append the request values to the URL. But there are occasions on which it is not enough and you need to use the FORM ENCODING format

user_agent="Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36"
curl -vvv -G http://localhost:8000/test -H "User-Agent: $user_agent" -d query=scope=1

 Connected to localhost (127.0.0.1) port 8000 (#0)
> GET /test?query=scope=1 HTTP/1.1
> Host: localhost:8000
> Accept: */*
> User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36
> 
 HTTP 1.0, assume close after body
< HTTP/1.0 404 File not found
< Server: SimpleHTTP/0.6 Python/3.11.4
< Date: Mon, 14 Aug 2023 12:28:11 GMT
< Connection: close
< Content-Type: text/html;charset=utf-8
< Content-Length: 335

This method asks for the same headers which will be returned with the get method. It is useful in some contexts as small computer capabilities. Imagine you haven’t RAM available. You, could ask first for the headers of the request, evaluate the content-length property and act according to this value.

The method OPTIONS retrieves a list of methods availables for a resource. This method is implement by default in most of the servers

curl -X OPTIONS https://example.org -i

HTTP/2 200 
allow: OPTIONS, GET, HEAD, POST
cache-control: max-age=604800
content-type: text/html; charset=UTF-8
date: Wed, 16 Aug 2023 15:06:45 GMT
expires: Wed, 23 Aug 2023 15:06:45 GMT
server: EOS (vny/044F)
content-length: 0

The POST method allows to send data to the server. Normally, this method, produces a change in the state of the server, for example, when a login process ends successfully, the server creates a session for the user and works in a different way. That means that the post method is not indepondent.

POST /test HTTP/1.1
Host: foo.example
Content-Type: application/x-www-form-urlencoded
Content-Length: 27

field1=value1&field2=value2

With this method, we can create or update an existing resource. It means that the method is indepondent.

PUT /new.html HTTP/1.1
Host: example.com
sontent-type: text/html
Content-length: 16

<p>New File</p>

When a request gets a code between 100 and 199, the value of the response is informative

In this case, the request ends successfully. The most common response is 200 which means OK. But there is a lot of entries.

With this response, the client should make another request following a new URL because the resource has been moved temporally or permanent

When the client gets an error code between 400 and 499, the client performs the request with some errors that should be fixed before trying again. These errors could be from a badly formed URL to an incorrect data provided to the server, including trying to access some inexistent resource, the famous 404 Page not found

With the 5XX error, the server informs the client, that there was an error processing the request, but it could be temporally and the error is not caused by a client’s action.

Mozilla documentation status code