Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!vsi1!ubvax!mrspoc!itkin
From: itkin@mrspoc.UUCP (Steven M. List)
Newsgroups: comp.databases
Subject: Re: ACCELL/CP - Any users with thoughts!
Message-ID: <7139@mrspoc.UUCP>
Date: 26 Apr 89 04:16:20 GMT
References: <7495@charlie.OZ>
Reply-To: itkin@mrspoc (Steven List)
Organization: Transact Software, Inc., Mt. View, CA
Lines: 49

In article <7495@charlie.OZ> wayne@libra.cc.deakin.OZ () writes:
> Are there any users of ACCELL/CP that can give me
> feedback as to its performance (good/bad?). Does it free
> the processor of I/O significantly to improve database
> performance?
> 
I've worked with ACCELL/CP somewhat.  Certainly enough to offer an
opinion (actually, it doesn't take much for me to offer an opinion
:^>~).  The design goals of ACCELL/CP are good.  The implementation
leaves a bit to be desired, but only from certain perspectives.

To explain:  ACCELL/CP DOES indeed offload the host processor
significantly.  Both Unify's testing and my own lead clearly to that
conclusion.  The effect of ACCELL/CP is to LEVEL performance.  That is,
the response for each user will be pretty much the same regardless of
whether there is one user or there are 16 users.  This is largely a
function of the fact that the PC is performing much of the local field
editing and cursor movement.  The cost, however, is that the PC MUST
communicated with the host EACH TIME YOU MOVE BETWEEN FIELDS!  Thus, for
one user, there is still a noticeable pause when you press RETURN before
the cursor moves to the next field.

The place where you will see a noticeable improvement is when you return
(PREV FORM) to previous forms.  Since the PC using ACCELL/CP will be
caching forms lower on the stack, they pop up IMMEDIATELY.  My problem
is that this is a small benefit.  The cost in the field-to-field
movement is far higher than the savings in popping forms off the stack.
Where I think there is the potential for far better gains will be the
networked version of ACCELL/CP whenever that becomes a reality.

I think that the biggest problem with ACCELL/CP is that cost of
communicating between host and PC at terminal speeds (9600 or 19200).
There is one other problem that we experienced with ACCELL/CP: it was
apparently not well tested with multi-occurrence forms (one of my
favorite feature of ACCELL).  It frequently bombs out with messages
about the "host not cooperating".  Since most of my applications use
multi-occurrence forms liberally, this pretty well prevents me from
using ACCELL/CP even if I really wanted to.

For me, the net is that I don't plan to use ACCELL/CP until and if the
performance is reasonable with ONE user.  If you are planning an
installation with large numbers of users, it may make sense since it
does LEVEL performance.  You will get fewer complaints from users about
performance degrading, since it won't (or at least not significantly).
-- 
:  Steven List @ Transact Software, Inc. :^>~
:  Chairman, Unify User Group of Northern California
:  {apple,coherent,limbo,mips,pyramid,ubvax}!mrspoc!itkin
:  Voice: (415) 961-6112