Is there a public HTTP 1.1 reference implementation?

Question

While learning more about HTTP 1.1 and reading the spec, it strikes me that it could be helpful to have a public reference implementation which can demonstrate the protocol. I imagine it would provide ideal, basic examples, as well as working examples of those parts of the protocol which are often disabled on public servers (e.g., TRACE).

I'm talking about a running, publicly accessible server(s). The idea would be to show how HTTP (should) works via an actual running webserver(s) (and the source). A user could build arbitrary requests using fiddler or the like, to see how the server responds. I'm assuming it would be open source. It would likely be based on an existing webserver implmentation (e.g., Apache), perhaps with extensions to support the entire protocol where the existing impl. doesn't (Transfer-Encoding compression, etc.). I know this last part is a pipe dream, I'm just putting it here by way of explanation.

I understand that HTTP is a very broad protocol, so that a reference implementation would not be comprehensive. I can imagine many, many reasons why something like this would not exist, and I know I can start up my own local server and play around with it (I've done that sort of thing for years). I know I can poke around against well-known existing public servers (Google, etc.). But, I'm wondering if anything like a public reference implementation exists.

Answer 1

As an IETF spec, HTTP/1.1 does not have a reference implementation. Instead, "at least two independent interoperating implementations with widespread deployment and successful operational experience" were required.

From the Implementation report for HTTP/1.1 to Draft Standard, you can see there were substantially more than that:

We have implementation & testing reports from 26 implementations

You say:

I can imagine many, many reasons why something like this would not exist

Here's one: for a reasonably complex specification, you don't want people designing to a specific implementation. Any "reference" implementation would have bugs, which would then be picked up by subsequent code built against that reference.

The specification is authoritative; in the case that an implementation diverges, you should consult the specification (and its errata) for the correct behaviour.

I know I can poke around against well-known existing public servers

Exactly. Per The Tao of IETF:

"We believe in rough consensus and running code"