195 lines
7.9 KiB
Plaintext
195 lines
7.9 KiB
Plaintext
Metadata-Version: 2.1
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Name: h11
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Version: 0.12.0
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Summary: A pure-Python, bring-your-own-I/O implementation of HTTP/1.1
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Home-page: https://github.com/python-hyper/h11
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Author: Nathaniel J. Smith
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Author-email: njs@pobox.com
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License: MIT
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Platform: UNKNOWN
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Classifier: Development Status :: 3 - Alpha
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Classifier: Intended Audience :: Developers
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Classifier: License :: OSI Approved :: MIT License
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Classifier: Programming Language :: Python :: Implementation :: CPython
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Classifier: Programming Language :: Python :: Implementation :: PyPy
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Classifier: Programming Language :: Python :: 3
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Classifier: Programming Language :: Python :: 3 :: Only
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Classifier: Programming Language :: Python :: 3.6
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Classifier: Programming Language :: Python :: 3.7
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Classifier: Programming Language :: Python :: 3.8
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Classifier: Programming Language :: Python :: 3.9
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Classifier: Topic :: Internet :: WWW/HTTP
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Classifier: Topic :: System :: Networking
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Requires-Python: >=3.6
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h11
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===
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.. image:: https://travis-ci.org/python-hyper/h11.svg?branch=master
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:target: https://travis-ci.org/python-hyper/h11
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:alt: Automated test status
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.. image:: https://codecov.io/gh/python-hyper/h11/branch/master/graph/badge.svg
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:target: https://codecov.io/gh/python-hyper/h11
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:alt: Test coverage
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.. image:: https://readthedocs.org/projects/h11/badge/?version=latest
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:target: http://h11.readthedocs.io/en/latest/?badge=latest
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:alt: Documentation Status
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This is a little HTTP/1.1 library written from scratch in Python,
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heavily inspired by `hyper-h2 <https://hyper-h2.readthedocs.io/>`_.
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It's a "bring-your-own-I/O" library; h11 contains no IO code
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whatsoever. This means you can hook h11 up to your favorite network
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API, and that could be anything you want: synchronous, threaded,
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asynchronous, or your own implementation of `RFC 6214
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<https://tools.ietf.org/html/rfc6214>`_ -- h11 won't judge you.
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(Compare this to the current state of the art, where every time a `new
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network API <https://trio.readthedocs.io/>`_ comes along then someone
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gets to start over reimplementing the entire HTTP protocol from
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scratch.) Cory Benfield made an `excellent blog post describing the
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benefits of this approach
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<https://lukasa.co.uk/2015/10/The_New_Hyper/>`_, or if you like video
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then here's his `PyCon 2016 talk on the same theme
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<https://www.youtube.com/watch?v=7cC3_jGwl_U>`_.
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This also means that h11 is not immediately useful out of the box:
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it's a toolkit for building programs that speak HTTP, not something
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that could directly replace ``requests`` or ``twisted.web`` or
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whatever. But h11 makes it much easier to implement something like
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``requests`` or ``twisted.web``.
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At a high level, working with h11 goes like this:
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1) First, create an ``h11.Connection`` object to track the state of a
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single HTTP/1.1 connection.
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2) When you read data off the network, pass it to
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``conn.receive_data(...)``; you'll get back a list of objects
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representing high-level HTTP "events".
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3) When you want to send a high-level HTTP event, create the
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corresponding "event" object and pass it to ``conn.send(...)``;
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this will give you back some bytes that you can then push out
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through the network.
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For example, a client might instantiate and then send a
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``h11.Request`` object, then zero or more ``h11.Data`` objects for the
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request body (e.g., if this is a POST), and then a
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``h11.EndOfMessage`` to indicate the end of the message. Then the
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server would then send back a ``h11.Response``, some ``h11.Data``, and
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its own ``h11.EndOfMessage``. If either side violates the protocol,
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you'll get a ``h11.ProtocolError`` exception.
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h11 is suitable for implementing both servers and clients, and has a
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pleasantly symmetric API: the events you send as a client are exactly
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the ones that you receive as a server and vice-versa.
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`Here's an example of a tiny HTTP client
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<https://github.com/python-hyper/h11/blob/master/examples/basic-client.py>`_
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It also has `a fine manual <https://h11.readthedocs.io/>`_.
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FAQ
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---
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*Whyyyyy?*
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I wanted to play with HTTP in `Curio
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<https://curio.readthedocs.io/en/latest/tutorial.html>`__ and `Trio
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<https://trio.readthedocs.io>`__, which at the time didn't have any
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HTTP libraries. So I thought, no big deal, Python has, like, a dozen
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different implementations of HTTP, surely I can find one that's
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reusable. I didn't find one, but I did find Cory's call-to-arms
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blog-post. So I figured, well, fine, if I have to implement HTTP from
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scratch, at least I can make sure no-one *else* has to ever again.
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*Should I use it?*
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Maybe. You should be aware that it's a very young project. But, it's
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feature complete and has an exhaustive test-suite and complete docs,
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so the next step is for people to try using it and see how it goes
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:-). If you do then please let us know -- if nothing else we'll want
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to talk to you before making any incompatible changes!
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*What are the features/limitations?*
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Roughly speaking, it's trying to be a robust, complete, and non-hacky
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implementation of the first "chapter" of the HTTP/1.1 spec: `RFC 7230:
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HTTP/1.1 Message Syntax and Routing
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<https://tools.ietf.org/html/rfc7230>`_. That is, it mostly focuses on
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implementing HTTP at the level of taking bytes on and off the wire,
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and the headers related to that, and tries to be anal about spec
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conformance. It doesn't know about higher-level concerns like URL
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routing, conditional GETs, cross-origin cookie policies, or content
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negotiation. But it does know how to take care of framing,
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cross-version differences in keep-alive handling, and the "obsolete
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line folding" rule, so you can focus your energies on the hard /
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interesting parts for your application, and it tries to support the
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full specification in the sense that any useful HTTP/1.1 conformant
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application should be able to use h11.
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It's pure Python, and has no dependencies outside of the standard
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library.
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It has a test suite with 100.0% coverage for both statements and
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branches.
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Currently it supports Python 3 (testing on 3.6-3.9) and PyPy 3.
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The last Python 2-compatible version was h11 0.11.x.
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(Originally it had a Cython wrapper for `http-parser
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<https://github.com/nodejs/http-parser>`_ and a beautiful nested state
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machine implemented with ``yield from`` to postprocess the output. But
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I had to take these out -- the new *parser* needs fewer lines-of-code
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than the old *parser wrapper*, is written in pure Python, uses no
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exotic language syntax, and has more features. It's sad, really; that
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old state machine was really slick. I just need a few sentences here
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to mourn that.)
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I don't know how fast it is. I haven't benchmarked or profiled it yet,
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so it's probably got a few pointless hot spots, and I've been trying
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to err on the side of simplicity and robustness instead of
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micro-optimization. But at the architectural level I tried hard to
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avoid fundamentally bad decisions, e.g., I believe that all the
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parsing algorithms remain linear-time even in the face of pathological
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input like slowloris, and there are no byte-by-byte loops. (I also
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believe that it maintains bounded memory usage in the face of
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arbitrary/pathological input.)
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The whole library is ~800 lines-of-code. You can read and understand
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the whole thing in less than an hour. Most of the energy invested in
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this so far has been spent on trying to keep things simple by
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minimizing special-cases and ad hoc state manipulation; even though it
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is now quite small and simple, I'm still annoyed that I haven't
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figured out how to make it even smaller and simpler. (Unfortunately,
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HTTP does not lend itself to simplicity.)
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The API is ~feature complete and I don't expect the general outlines
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to change much, but you can't judge an API's ergonomics until you
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actually document and use it, so I'd expect some changes in the
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details.
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*How do I try it?*
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.. code-block:: sh
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$ pip install h11
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$ git clone git@github.com:python-hyper/h11
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$ cd h11/examples
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$ python basic-client.py
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and go from there.
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*License?*
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MIT
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*Code of conduct?*
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Contributors are requested to follow our `code of conduct
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<https://github.com/python-hyper/h11/blob/master/CODE_OF_CONDUCT.md>`_ in
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all project spaces.
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