This is the first developer prerelease of the Snap Framework HTTP Server
library. For more information about Snap, read the
README.SNAP.md or visit
the Snap project website at http://www.snapframework.com/.
The Snap HTTP server is a high performance, epoll-enabled, iteratee-based web
server library written in Haskell. Together with the
snap-core library upon
which it depends, it provides a clean and efficient Haskell programming
interface to the HTTP protocol. Higher-level facilities for building web
applications (like user/session management, component interfaces, data
modeling, etc.) are not yet implemented, so this release will mostly be of
interest for those who:
- need a fast and minimal HTTP API at roughly the same level of abstraction as Java servlets,
- are interested in contributing to the Snap Framework project.
To build the Snap HTTP server, you need to
cabal install the
library (which should have come with this package).
The snap-server library can optionally use the libev for high-speed, O(1) scalable socket event processing.
If you decide to use the libev backend, you will also need to download and install the darcs head version of the hlibev library:
$ darcs get --lazy http://code.haskell.org/hlibev/ $ cd hlibev $ cabal install -O2 (or "cabal install -O2 -p" for profiling support)
It has some new patches that we rely upon.
for the "stock" version of Snap or
cabal install -flibev
for the libev-based backend.
The haddock documentation can be built using the supplied
The docs get put in
Snap is still in its very early stages, so most of the "action" (and a big chunk of the code) right now is centred on the test suite. Snap aims for 100% test coverage, and we're trying hard to stick to that.
To build the test suite,
cd into the
test/ directory and run
$ cabal configure # for the stock backend $ cabal configure -flibev # for the libev backend $ cabal build
From here you can invoke the testsuite by running:
The testsuite generates an
hpc test coverage report in
cabal project also builds an executable called "pongserver" which is
a test HTTP server, hardcoded to run on port 8000:
$ ./dist/build/pongserver/pongserver +RTS -A4M -N4 -qg0 -qb -g1
(Those are the RTS settings that give me the highest performance on my quad-core Linux box running GHC 6.12.1, your mileage may vary.)
This server just outputs "PONG" but it is a complete example of an HTTP application (FIXME: currently this isn't true, we need to make pongserver run in the still-incomplete Snap monad):
$ curl -i http://localhost:8000 HTTP/1.1 200 OK Content-Length: 4 Date: Sun, 14 Mar 2010 03:17:45 GMT Server: Snap/0.pre-1 PONG