[web-devel] On the state of Haskell web frameworks

[Curt Sampson]

On 2010-03-16 02:03 -0400 (Tue), Gregory Collins wrote:

> I think I agree with you completely. The question is: where do you
> draw the lines?

I like to draw the real line, as best as possible, at "do the minimal
possible processing to the request" and let users chose a library to
process the request and handle as much as possible.

Let me expand on your examples, offering examples of reasonable
situations in which one wants the opposite behaviour of your (also
reasonable!) situations.

> You probably want transfer-encodings handled for you....

Let's say on my server I store a lot of static content in gzip'd form.
In this case, I certainly want to be handling the transfer-encoding myself,
because I don't want to uncompress my compressed copy to send it to the
server, only so that the server can compress it again as it sends it.

> Another example: we treat responses differently based on whether you
> explicitly set a content length or not. If the connection is HTTP/1.0,
> and you don't set a content length, we have to set "Connection: close"
> in the response headers and close the socket when we're finished
> sending the response....

Another approach would be to have interface library buffer the response
as it's being generated and, when it's complete, calculate the content
length and pass it on to the web server. In the case of a web server
doing a lot of relatively small requests, this would probably be
considerably more efficient. But of course you still need to the ability
to send out the response as it's being generated for large responses
that quickly produce some data, but take a relatively long time to
produce all of the data.

> How much of that sort of logic goes into the interface layer?

I'm not sure what you mean by "interface layer," but I feel that, as
much as possible, that sort of logic should be in standalone libraries
that go between the "standard" web server interface and the user
application.

cjs
-- 
Curt Sampson         <cjs at cynic.net>         +81 90 7737 2974
             http://www.starling-software.com
The power of accurate observation is commonly called cynicism
by those who have not got it.    --George Bernard Shaw