bringert at cs.chalmers.se
Tue Feb 13 03:55:38 EST 2007
On Feb 12, 2007, at 23:27 , Albert Y. C. Lai wrote:
> Bjorn Bringert wrote:
>> pwrapper is not an HTTP server, though the Haddock comment can
>> make you think so. pwrapper allows you to talk *CGI* over a TCP
>> port, but I have no idea why anyone would like to do that.
> Here is a scenerio. I want a basic web application: someone makes a
> request, and my program computes a response.
> * For one reason or another, I settle with CGI.
> * The program is huge and slow to load. (Let's say it statically
> links in the whole GHC API and therefore is basically GHC
> itself. :) ) It would suck to re-load this program at every request.
> * Or, the program performs work that requires more file-system
> privilege than the admin of the web server grants. You know, a good
> admin sets up a web server and all CGI scripts to run with nobody's
> * Or, nevermind performance or privilege. I am a cheapo, and I use
> a cheapo hosting provider, which only provides me with 3MB of
> storage. My program weighs 17MB (recall that it links in the whole
> GHC :) ).
> Here is a solution. The program runs as a daemon and never quits;
> it can run somewhere with sufficient privilege and storage. It
> talks CGI over TCP. At the web server, which is super-slow, super-
> paranoid, and super-cheapo, the CGI script is a lightweight C
> program that redirects everything over TCP to my daemon.
> (Here is a counter-solution. The program still runs as a daemon
> somewhere, but it talks my own protocol over TCP. The CGI script is
> a lightweight C program that parses CGI into my own protocol.
> Besides having to design my own protocol carefully, here is a
> problem: C is a great language for writing parsers that are
> incomplete, inconsistent, and insecure. :) )
OK, that sounds reasonable, but I think that there are better
solutions for those problems. Besides, it's niche stuff that I don't
think belongs in the main CGI package. If anything wants it, it's
easy to implement.
* If you have slow start-up, you can use FastCGI instead of CGI.
There is already a Haskell library for that.
* If the program needs additional privileges, you can use an external
FastCGI program which is started independently of the server.
* If you have cheapo hosting, at least Apache mod_fastcgi allows you
to run your FastCGI app on a different machine. Another solution
would be mod_rewrite + mod_proxy. But if you have another server
where you can run your application, why not put your web server there
instead of using cheapo hosting?
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