I am using it on http://pass.net which is live in production but not
yet high volume. I hope to have some other projects live soon, but
they are currently works in progress.
On Tue, 6 Jun 2006, Joel Reymont wrote:
> Is anyone using HAppS in production right now?
> It seems to be the most advanced Haskell web development platform right now
> but I would like to hear about others as well. Production (heavy) use is what
> I'm looking for.
> Thanks, Joel
> http://wagerlabs.com/ >
> Haskell-Cafe mailing list
> [hidden email] > http://www.haskell.org/mailman/listinfo/haskell-cafe >
On Jun 7, 2006, at 9:08 PM, S. Alexander Jacobson wrote:
> I am using it on http://pass.net which is live in production but
> not yet high volume. I hope to have some other projects live soon,
> but they are currently works in progress.
On Wed, 7 Jun 2006, Joel Reymont wrote:
> What type of machine are you running this on?
> What type of memory usage are you seeing?
> Under what kind of load?
> How much memory per connection?
"darcs get http://pass.net/s/repo" and you can experiment for
yourself. If you have SearchPath installed <http://searchpath.org>
you just run "sh build.sh" in the Pass.net root directory. FYI, I do
development on a windows machine and deployment is on an old 1and1 web
> Are you running the naked HAppS web server?
I have multiple HAppS applications running on different internal ports
on the default 1and1 machine. Some of them are only handling http.
Others are handling inbound email as well. So for http, I am using
Apache as a secure server side caching proxy that dispatches
http(s)://pass.net to localhost:9000 and I am using sendmail to SMTP
relay mail for certain domains to e.g. localhost:2525 But, if this was
the only app on the machine, I probably would run HAppS naked.
> Have you done any time of performance testing?
Our internal benchmark tests had simple HAppS apps performing faster
than Apache. But these sorts of tests are very application dependent
so you will have to test your own apps.
FYI, we have achieved this level of performance without doing much in
the way of optimization. If you truly have a need for speed, the nice
thing about HAppS is that the MACID monad architecture gives you
orders of magnitude headroom for certain sorts of applications.
In particular, currently HAppS works as an integrated binary that
aggregates events from the network into a totally ordered stream that
is then processed sequentially by your application code. But it would
not be all that hard to separate the code into processes that creates
streams, proceses that merge/distribute streams, and one process that
runs your app on the merged stream.
In this sort of architecture all of the work of HTTP and TCP gets
offloaded onto stream creators running slave machines and your app
effectively operates as a process that simply reads a binary parsed
stream from stdin and writes one to stdout.
To see why this gives you so much performance headroom, think about
operating a sequential number service. A sequential number service is
a service that produces numbers in order with no gaps. Notice that
this is a really really simple service. But also notice that the
standard web site architecture will cap your performance at around 10k
requests per second and you won't be able to improve performance much
by buying new machines!
In contrast by patitioning your HAppS application as I described you
max out at 1m requests per second. Note: I don't know what the cap
is, but reading binary from stdin is orders of magnitude simpler than
prcessing HTTP and TCP so getting a 100x improvement should not be
On Thu, 8 Jun 2006, Joel Reymont wrote:
> On Jun 7, 2006, at 10:20 PM, S. Alexander Jacobson wrote:
>> Does this make sense?
> Makes sense but almost sounds too good.
:-) To be clear, the separation via binary streams has not yet been
implemented. I plan to do so only if I need it. If you get to that
scale first, then you get to do it :-/.
FYI, I am currently funding a modification to HAppS back end
logging/persistence system to allow the user to switch easily between
disk and Amazon S3. For my apps, I'm willing to add 1.5x S3 latency
in exchange for not having to worry about maintainin a reliable RAID
disk subsystem with hardware failover and managing off-site backup.
Not sure whether this feature is useful for your intended apps.
> What package would you recommend I use with HAppS to merge HTML
> templates with application data?
My apps including Pass.net use XSLT. For HTTP, HAppS looks at the
user-agent and if the browser does XSLT then it serves out XML with an
XSLT PI at the top. If the browser doesn't support XSLT then it run
xsltproc on the server. I don't think any MUA implements XSLT so the
XML mail sending agent runs all outbound mail through xsltproc on the
Note: the implementation of browser xslt detection here is very warty.
I'd love it if someone else wanted to take some time to clean it up.