The HTTP 1.0 specification (RFC 1945) officially defined only the GET, HEAD and POST methods, leaving open the possibility of adding extension methods:
Method = "GET" ; Section 8.1
| "HEAD" ; Section 8.2
| "POST" ; Section 8.3
The specification of HTTP 1.1 (as its last 1999 incarnation RFC 2616) defines explicitly other methods:
Method = "OPTIONS" ; Section 9.2
| "GET" ; Section 9.3
| "HEAD" ; Section 9.4
| "POST" ; Section 9.5
| "PUT" ; Section 9.6
| "DELETE" ; Section 9.7
| "TRACE" ; Section 9.8
| "CONNECT" ; Section 9.9
Of these methods, the more interesting ones due to their usage in RESTful applications are GET, POST, PUT and DELETE:
- GET is a safe, idempotent method and it is used to retrieve a resource.
- POST is considered a catch-all method nowadays, but its intent is defining a subordinate resource to the current one. For instance, posting to a blog resource may create a new post.
- PUT is the analogue of GET used to send a resource to the HTTP server.
- DELETE is the analogue of GET used to, of course, delete a particular resource.
GET and POST are the bread and butter of requests sent towards PHP applications. They are commonly generated directly by the browser. A GET request is generated by a link or a form with the specified method attribute set as get. A POST request instead is usually obtainable in native HTML 4 only with a form, which may contain also an enctype attribute to set the Content-Type header of the request (usually employed for the upload of files via POST method.)
But how can we detect the HTTP request method in a PHP script? For the common methods, such as GET and POST, the superglobal arrays $_GET and $_POST are always available and contain the request parameters. You may want to wrap them with an object-oriented interface, and note that in the case of files upload via POST you should also look at the $_FILES superglobal array.
For the other methods, the first thing to do is setting up your webserver with a directive that routes all the PUT requests to a single, dynamic entry point. In the case of Apache, this is described in the PHP manual as:
Script PUT /put.phpThe pointed script simply has to read from the standard input the PUT request:
$putdata = fopen("php://input", "r");file_get_contents() won't work here; welcome back to the world of CGI! :)
The manual and the user comments are also a valuable resource for common pitfalls in implementing this type of endpoints.
With regard to the DELETE requests, the same configuration is valid to route the requests to a single entry point. Then, it's a matter of identifying the right environment variables, which may vary depending on your HTTP server. Fortunately, PHP frameworks do most of the work, and you are free to programmatically implement different behaviors depending on the type of the request.