JRhine> When I want to render an object, I first instantiate the object,
JRhine> and invoke 'compute_lastmod' on it. I compare the return value
JRhine> with the timestamp of an on-disk copy of the last rendering. If
JRhine> they are the same, I simply serve the file off disk...
KH> This has the disadvantage of leaving the user to wait until your
KH> render is done. Otherwise for large options you could be presenting
KH> the object while rendering, thus decreasing the overall display time
KH> and increasing user satisfaction.
True, but I'm not sure what your objection is. In the vast majority of
cases, object rendering time is inconsequential compared to network lag and
client rendering time. Being able to incrementally render client side isn't
that big of a win; the time difference between streaming to the client as
the object is rendering and waiting until it is done before sending is no
more than a few tenths of a second at the greatest and does not
substantially affect perceived performance. In any case, this model is
unavoidable because in many cases, dynamic objects do not follow a linear
rendering flow; that is to say, I can't properly render the top until I've
processed all the data for the object.
There is a possible exception for heavily loaded servers that take on the
order of seconds to render objects; in this case, there would be a
noticeable difference is response time. In that case, since you're working
with dynamic objects, just distribute the buggers to reduce server load.
Clean, simple, and cheap.
Hmmm, I just considered objects that inherently take a long time to render
regardless of server load (databases and such). My objects aren't like that
(yet), so I haven't had to deal with it. In that case, you would indeed
want some mechanism to present some feedback to the user early; in this
case, we will obviously need some kind of boundary or packetized data
scheme; no getting around that, I suspect, if we want accurate entity-body
delimiting.
-- Jared_Rhine@hmc.edu / HMC / <URL:http://www.hmc.edu/~jared/home>"I regret to say that we of the F.B.I. are powerless to act in cases of oral-genital intimacy, unless it has in some way obstructed interstate commerce." -- J Edgar Hoover