[plt-scheme] unit-based servlet vs module-based servlet?

On 4/11/07, Yin-So Chen <yinso.chen at gmail.com> wrote:
> Really?!  Not being familiar with the history of PLT scheme I have to say I
> am surprised by the answer - I would have thought module is an older
> concept.  Sounds like you are saying unit is slowly fading away?

Oh, no! I wouldn't say that. It was just that, in the past, unit was
our top-level program structure, but we soon realized that units work
better as a general tool for constructing programs and we needed a
more first-order construct for just defining the top-level program
structure (in order to make compilation more tractable, etc).

I'm using "we" in the loosest possible sense here. It was Scott Owens
and Matthew Flatt who really nailed down the difference and explained
it properly. Probably they can point you to some writings or say more
about it.

> Can module based servlets be loaded/unloaded on demand like unit-based
> servlets?  And would badly written module servlet bring down the server?
> Unit servlets appear to handle the above fine, but if module servlet also
> works, then I am not sure if there are discernible differences (although
> there are still more unit-servlet examples in the doc).

I think these questions are all answered the same way, regardless of
whether or not you use a module servlet or a unit servlet.

I should probably defer to Jay, tho. There may be some issues I'm not
up to speed with in the web server.

Robby

> Thanks,
> yinso
>
>
> On 4/11/07, Robby Findler <robby at cs.uchicago.edu> wrote:
> > I suspect that most everyone wants to use module servlets these days,
> > not unit servlets. Once upon a time, we didn't have modules (and
> > servlets existed at that time), so we used units. Nowadays, modules
> > work much better with all of our other tools (like the compiler, for
> > example, but also the module browser and things like that), that you
> > really want your program to be in a module.
> >
> > That said, of course, if your program calls for the power of units,
> > use the units inside the module!
> >
> > Robby
> >
> > On 4/11/07, Yin-So Chen <yinso.chen at gmail.com> wrote:
> > > Hi all -
> > >
> > > yet another newbie question - what is the difference between unit-based
> > > servlet and module-based servlet and when to choose which?  Are the two
> > > comparable in terms of capabilities?  I look at the unit doc and notices
> > > that it is analogous to a pluggable component and hence appears to have
> more
> > > flexibility and power than module, so was wondering under what
> situations
> > > would a module servlet be preferrable over a unit servlet.
> > >
> > > Thanks,
> > > yinso
> > >
> > > --
> > > http://www.yinsochen.com
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