Re: Data transfer between codes on different machines

[netcomsv!mork!loren@decwrl.dec.com (Loren Hart)]

mjl-b@minster.york.ac.uk (Mathew Lodge) writes:
: mishra@controls.ccd.harris.com (Sanjoy Mishra) writes:
: >I have code running on two different machines. Is there any interface
: >which I can use structural data between these two machines. It is possible
: >that two machines have ADA compiler from two different vendors.
: 
: Theoretically, you can use record representation clauses to specify the
: exact data layout at bit-level. Theoretically because the compiler may still
: add stuff to the record that it doesn't tell you about.
: 
: Different implementations may also have different ideas about bit numbering a
nd
: the like, but you can avoid that by checking appendix F of each compiler
: manual.
: 

Actually, it can get much worse than that.  Different machines store
integers in different byte orders.  Additionally, floating point numbers are
notoriously non-portable.  The only way to guarentee that files are
portable is to make sure to use some consistent format for all data
types.  The easiest portable method is to store all data as ascii
strings, although there may be a severe performance cost to this
approach.
-- 
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Mr Loren L. Hart                                       The Ada Ace Group, Inc
loren@netcom.com                                       P.O. Box 36195
				                       San Jose, CA  95158