From: Kirk Haines <khaines@...>
Date: 2005-08-07T02:08:44+09:00
Subject: Re: Remote require

On Saturday 06 August 2005 7:28 am, James Britt wrote:

> > Even so, it's easy enough to hack asimple version together, but the key
> > would be caching (and checking for updates periodically?)
>
> I figure whenever the code is run it would just fetches the remote file
> and get the  latest version.  Different story for long-running apps and
> processes.

Caching isn't a hard problem to solve.  I have a Webcache class in my current 
IOWA source that should do the trick.  It is based off of an LRU cache.  It's 
not packaged seperately, but you're welcome to take it and modify as 
necessary, or you can tell me what you would like to see changed and I can 
seperate it into it's own mini-project.  Current usage looks like this:

cache_size = 20
webcache = Iowa::Webcache.new(cache_size) # defaults to 100
url = 'http://www.superbad.com/rubylib/soul.rb'
content = webcache[url]

It makes use of 'etag', 'last-modified', and 'expires' headers on content in 
order to try to do the correct thing regarding caching, and when asked for 
something it has already retrieved, just does a HEAD request on that item in 
order to try to determine if the content has changed.

It was written for a specific purpose (a smart <img> tag that automagically 
determines height and width of the image and puts that into the generated 
HTML), so it has a default or two that probably should become configurable 
items, such as the default time-to-live on content that doesn't have an 
'expires' header.


Thanks,

Kirk Haines