Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!apple!oliveb!pyramid!prls!philabs!ppgbms!paul
From: paul@ppgbms (Paul Evan Matz)
Newsgroups: comp.windows.news
Subject: Re:  C Client arrays
Summary: Comments on Example for sending array data from client to server
Keywords: array_data NeWS
Message-ID: <659@ppgbms.UUCP>
Date: 5 Mar 89 21:23:03 GMT
References: <8903010054.AA06125@bill.capmkt.com>
Reply-To: ppgbms!moe!paul@philabs.philips.com (Paul Evan Matz)
Distribution: na
Organization: PPG Biomedical Sys., Pleasantville, NY.
Lines: 46

In article <8903010054.AA06125@bill.capmkt.com> tim@capmkt.UUCP writes:
>
>/*** the cps defs ***/
>
>cdef arraystart() 
>       [
>
>cdef arrayend()
>       ]
>
>cdef emit_double(double val)
>       val
>

You might want to build into the cdef functions the array identifier 
assignment part too, like:

cdef arraystart() 
       ArrayDataName [

cdef arrayend()
       ] def

One *VERY* big problem with this method is that the array data is being
put on the stack of the server side liteweight process, so if you're
trying to pass an array bigger than 1000 words, look out for a stack
overflow!  (I've heard there is a way to increase the stack size, but
have never found out how).

Another problem with this method is that the data being passed is translated
into ascii by the client, sent on the byte stream connection to the server, 
who then translates it back to binary whatever.  Kinda slow.  Depending on what
you are doing with the data, it is sometimes better to use some of the
cdef intrinsics like ps_moveto, ps_lineto;  I think the passed parameters are
tokenized in an XDR-like way (I can't remember where I read this.  I could
be completely off base on this, but I don't think so).

Maybe Sun will provide a decent binary array transmission mechanism in the
X11/NeWS merge.  Anybody care to comment?

	Paul Matz
	PPG Biomedical Systems
	One Campus Drive
	Pleasantville, NY. 10570
	914-741-4685
	path ppgbms!moe!paul@philabs.philips.com