What's the difference between a POST and a PUT HTTP REQUEST?

Question

They both seem to be sending data to the server inside the body, so what makes them different?

Answer 1

PUT is meant as a a method for "uploading" stuff to a particular URI, or overwriting what is already in that URI.

POST, on the other hand, is a way of submitting data RELATED to a given URI.

Refer to the HTTP RFC

Answer 2

Semantics.

a HTTP PUT is supposed to accept the body of the request, and then store that at the resource identified by the URI.

A HTTP POST is more general. It is supposed to initiate an action on the server. That action could be to store the request body at the resource identified by the URI, or it could be a different URI, or it could be a different action.

PUT is like a file upload. A put to a URI affects exactly that URI. A POST to a URI could have any effect at all.

Answer 3

A POST is considered something of a factory type method. You include data with it to create what you want and whatever is on the other end knows what to do with it. A PUT is used to update existing data at a given URL, or to create something new when you know what the URI is going to be and it doesn't already exist (as opposed to a POST which will create something and return a URL to it if necessary).

Answer 4

HTTP PUT:

PUT puts a file or resource at a specific URI, and exactly at that URI. If there's already a file or resource at that URI, PUT replaces that file or resource. If there is no file or resource there, PUT creates one.

HTTP 1.1 RFC location for PUT

HTTP POST:

POST sends data to a specific URI and expects the resource at that URI to handle the request. The web server at this point can determine what to do with the data in the context of the specified resource.

The official HTTP RFC specifies POST to be:

• Annotation of existing resources;
• Posting a message to a bulletin board, newsgroup, mailing list, or similar group of articles;
• Providing a block of data, such as the result of submitting a form, to a data-handling process;
• Extending a database through an append operation.

HTTP 1.1 RFC location for POST

Difference between POST and PUT:

The RFC itself explains the difference:

The fundamental difference between the POST and PUT requests is reflected in the different meaning of the Request-URI. The URI in a POST request identifies the resource that will handle the enclosed entity. That resource might be a data-accepting process, a gateway to some other protocol, or a separate entity that accepts annotations. In contrast, the URI in a PUT request identifies the entity enclosed with the request -- the user agent knows what URI is intended and the server MUST NOT attempt to apply the request to some other resource. If the server desires that the request be applied to a different URI,

Using the right method, unrelated aside:

One benefit of REST ROA vs SOAP is that when using HTTP REST ROA, it encourages the proper usage of the HTTP verbs/methods. So for example you would only use PUT when you want to create a resource at that exact location. And you would never use GET to create or modify a resource.

Answer 5

To give examples of REST-style resources:

"POST /books" with a bunch of book information might create a new book, and respond with the new URL identifying that book: "/books/5".

"PUT /books/5" would have to either create a new book with the id of 5, or replace the existing book with ID 5.

In non-resource style, POST can be used for just about anything that has a side effect. One other difference is that PUT should be idempotent - multiple PUTs of the same data to the same URL should be fine, wheras multiple POSTs might create multiple objects or whatever it is your POST action does.

Answer 6

Others have already posted excellent answers, I just wanted to add that with most languages, frameworks, and use cases you'll be dealing with POST much, much more often than PUT. To the point where PUT, DELETE, etc. are basically trivia questions.