Why is the HTTP verb POST called POST?

Question

The other verbs all make sense to me, but I don't have much context for "post" as a verb. Is it like post as in Post Office (which makes some sense, although seems like a stretch) or post like post on a bulletin board (makes less sense to me)? Does anyone know who decided on "POST" and why it was selected?

Answer 1

Well, "post like post on a bulletin board" comes pretty close to the answer, I guess. In the end, that's exactly one of those functionalities this method was designed for. POST is always meant to post stuff to some kind of 'factory' to be handled by it - otherwise you could just use PUT. Let's have a look at RFC2616, Section 9.5:

The POST method is used to request that the origin server accept the entity enclosed in the request as a new subordinate of the resource identified by the Request-URI in the Request-Line. POST is designed to allow a uniform method to cover the following functions:

  - 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.

Of course this is not the exact definition of why it is called POST, but I think this might give some clues about the idea behind it.

Maybe we could also have a look at some meanings of the word 'post' (http://www.thefreedictionary.com/Post, the 3rd definition) - according to that, post as a verb can mean

• To mail (a letter or package)
• To inform of the latest news
• To transfer (an item) to a ledger in bookkeeping
• To make the necessary entries in (a ledger)

And this is exactly what POST does (metaphorically). If you want to send en email, you let your email-provider handle it and then inform you about the state. And this is also the difference between PUT and POST: If the client is in charge of handling the resource, you use PUT (because you know what to put and where to put it).

So, theoretically, if you knew the IP-address of the person you want to send the email to, you wouldn't need your provider to find this stuff out for you. But now, you know what to put, but not exactly where. So in this case, you use POST. You 'inform the server of the latest news' and the server decides where to put it. So you can think of it as 'transfering an item' to a resource that's already present (like a thread in a forum or something) - you just want to append something.

I hope this makes any sense...