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Re: LWP::UserAgent and HTML::Parser and the joys of Open Source

by merlyn (Sage)
on Oct 15, 2001 at 18:18 UTC ( #118877=note: print w/replies, xml ) Need Help??

in reply to LWP::UserAgent and HTML::Parser and the joys of Open Source

For a more robust solution, you only want to push a HTML parser onto a stream that has announced itself as MIME-type of text/html. I did that for a client once, and have talked about the code in a recent Usenet article, and hope to have it published soon. In there, I said:
I have (unpublished) a dynamic-pre-forking Apache-style web streaming proxy server in about 300 lines of pure Perl (using HTTP::Daemon and the other LWP items, of course). It takes the same parameters as Apache child management:
### configuration my $HOST = ''; my $PORT = 42001; # 0 = pick next available user-port my $START_SERVERS = 4; # start this many, and don't g +o below my $MAX_CLIENTS = 12; # don't go above my $MAX_REQUESTS_PER_CHILD = 250; # just in case there's a leak my $MIN_SPARE_SERVERS = 1; # minimum idle (if 0, never start new) my $MAX_SPARE_SERVERS = 12; # maximum idle (should be "single brow +ser max")
And acts accordingly, using a simple scoreboarding mechanism similar to the Apache method.

Using this code, the apache-benchmark program shows that I'm only half as fast as Apache, and has one quarter the footprint!

The best part is that in those 300 lines, I handle full SSL streaming (the CONNECT call), full content streaming (I was watching live-feed quicktime movies through the proxy), and if the content-type is text/html, an HTML parser in token mode is inserted, allowing real-time rewriting. For example, I could insert <font color=blue> tags around all <a href=> links, while not impeding the stream of the rest of the HTML... there'd just be a hiccup while the <a href=> was being noticed.

The code was originally written as a work for-hire for a client who had intended my work to become open source. But the client dot-bombed, so I'm still trying to get clarification of whether I can release the code under my own copyright. As soon as that clears up, expect a WebTechniques column or two on it. :)

-- Randal L. Schwartz, Perl hacker

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