some HLL comments

Raul Miller
Mon, 6 Mar 95 13:19 EST

Jecel Mattos de Assumpcao Jr.
   > I haven't been able to read the very latest versions of the WWW
   > pages as the local server insists on giving me cached ( old )
   > versions of the pages :-(

Francois-Rene Rideau
   On netscape, the "reload" icon should flush this cache; but I'd
   recommend you have a local copy of the whole Tunes distribution,
   and then use the GNU patch utility to update it.  Patch is
   just out !

Nope.  This is one of the issues you have to deal with in a
distributed system: computational integrity with distributed data.
[And my "favorite" hobby horse: many people with computer science
training are used to thinking in terms of "atomic" operations which
maintain computational integrity, but distributed systems need some
form of instancing instead.]

The problem here is that Jecel does not have direct access to external
HTTP servers.  Instead, an http query is handled by a local server
which caches query results for some period of time.  During that time
period, the locally cached copy is used.  This saves communications
bandwidth when compared to fetching the same text from remote sites
every time someone looks at it.

There's several ways around this caching mechanism.  The "right way"
is to issue a unique id to web pages when they change.  Typically,
this means incrementing a version counter (or generating some sort of
hash code).

Another workaround is to fetch enough data from the web to flush the
cache of the server.  However, this isn't necessarily easy (or even a
good idea).  For instance, think about fetching several gigabytes of
information (for a server with a big local disk) across a 14.4 slip

Raul Miller