RE: Inter-robot Communications - Part II

David Eagles (eaglesd@planets.com.au)
Sat, 30 Dec 1995 09:06:36 +-1100


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I'll share a different idea I had about this stuff (oe, or do I need
to patent it first these days?). If in the distributed gathering part
we start sending URL's, HTTP response headers, and complete content,
doesn't the word "caching proxy" spring to mind? I need to think more
about this, but it sounds to me that if we had an efficient way of
updating and pre-loading distributed caches using a between-cache
protocol, we'd be killing two birds with one stone: better caching
performance than the current 30%, and complete freedom to do whatever
you want with the content for robot purposes...

I'd actually had the same idea, but admittedly hadn't thought of taking =
it as far as a distributed cache situation. I currently generate my =
database using the cache files from a fairly large Australian ISP. Just =
tar all the appropriate files I require (which is easy in the case of =
FunnelWeb because it uses domain names to determine if the data is =
relevant to it or not - I just tar *.au, *.nz, etc), then download them =
at let FunnelWeb go crazy. Accessing the local filesystem makes the =
initial data gathering very fast obviously, and I can then re-visit each =
host in the database and try a more thorough traversal of the site.

Now, if we had a distributed cache mechanism, I wouldn't need to grab =
their cache file anymore - the robot itself could either access the =
cache files directly, or talk to the local cache handler using the =
between-cache protocol.

The storage format of the CERN proxy-cache is quite convenient for file =
access by robots (except it should compress the data - I haven't looked =
at it lately, so if it does now please ignore the last comment).

Unfortunately, the same problems come up as I described in the last =
message. It is a waste of bandwidth, time and storage to completely =
duplicate entire caches. The ideal way would be to have some selection =
criteria, but what?

Later all,
David

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