Byte order writing to socket stream

Byte order writing to socket stream

[The Darkelf]

Hi, I have an Ada program with GNAT.Sockets that works fine when client
and server are in the same architecture. The problem is when client runs
on HP and the server on Intel, or viceversa.

It raises a STORAGE_ERROR exception, when it reads an array from the
socket stream. I guess the problem must be the byte order, so one solution
should be to write the size of the array(integer) and then the elements of
the array (strings), checking the integer byte order.

Can the conversion to the net standard be done "on the fly", as I do the
Stream'Output(stream,theArray), or it's necesary to manually output each
element?

If so, any suggestion for checking the architecture byte order and
ouputing it in some standard way?

May it be easier or better to just output the integer values as strings
(Integer'Image) ?

Thanks for your opinions and suggestions.

Alvaro J. Iradier Muro

Re: Byte order writing to socket stream

[Robert L. Klungle]

The Darkelf wrote:

> Hi, I have an Ada program with GNAT.Sockets that works fine when client
> and server are in the same architecture. The problem is when client runs
> on HP and the server on Intel, or viceversa.
>
> It raises a STORAGE_ERROR exception, when it reads an array from the
> socket stream. I guess the problem must be the byte order, so one solution
> should be to write the size of the array(integer) and then the elements of
> the array (strings), checking the integer byte order.
>
> Can the conversion to the net standard be done "on the fly", as I do the
> Stream'Output(stream,theArray), or it's necesary to manually output each
> element?
>
> If so, any suggestion for checking the architecture byte order and
> ouputing it in some standard way?
>
> May it be easier or better to just output the integer values as strings
> (Integer'Image) ?
>
> Thanks for your opinions and suggestions.
>
> Alvaro J. Iradier Muro

FWIW, had the same problem a while ago.
CORBA was an option (complex fix).
Doing byte swapping assumes apriori knowledge of incoming data format(s).
Did the string thing and all worked ok (although a little slower than otherwise).

cheers....bob

Re: Byte order writing to socket stream

[David C. Hoos]

----- Original Message ----- 
From: "The Darkelf" <darkelf@aim.homelinux.com>
Newsgroups: comp.lang.ada
To: <comp.lang.ada@ada.eu.org>
Sent: Friday, May 17, 2002 10:18 AM
Subject: Byte order writing to socket stream
<snip>
> If so, any suggestion for checking the architecture byte order and
> ouputing it in some standard way?
> 
I would use the package body of System.Stream_Attributes that
comes with glade (the Annex E implementation of GNAT)
(file name is s-stratt.adb) which modifies the stream attributes of
the numeric types to use the XDR network format.

You can compile this into your GNAT runtime and rebuild it.

 

Re: Byte order writing to socket stream

[Ted Dennison]

The Darkelf <darkelf@aim.homelinux.com> wrote in message news:<ac36va$m6qca$1@ID-107015.news.dfncis.de>...
> Hi, I have an Ada program with GNAT.Sockets that works fine when client
> and server are in the same architecture. The problem is when client runs
> on HP and the server on Intel, or viceversa.

You may want to look into using Gnat's Annex E support (GLADE), which
I believe deals with this issue *and* the communications issue. Both
sides have to be Ada, though.

-- 
T.E.D. 
Home     -  mailto:dennison@telepath.com (Yahoo: Ted_Dennison)
Homepage -  http://www.telepath.com/dennison/Ted/TED.html

Re: Byte order writing to socket stream

[Simon Wright]

dennison@telepath.com (Ted Dennison) writes:

> You may want to look into using Gnat's Annex E support (GLADE),
> which I believe deals with this issue *and* the communications
> issue. Both sides have to be Ada, though.

Clearly you could go to a lot to trouble to write C which understands
what GLADE does.

I don't know whether ACT make any guarantees about the stability of
the wire format used by their Annex E support between releases; to be
safe you might want to use the same release both ends.

You'd be most unlikely to get interoperability with other Ada
compilers (even if you could find one with Annex A support).

Re: Byte order writing to socket stream

[David C. Hoos, Sr.]

----- Original Message ----- 
From: "Simon Wright" <simon@pushface.org>
Newsgroups: comp.lang.ada
To: <comp.lang.ada@ada.eu.org>
Sent: May 18, 2002 1:47 AM
Subject: Re: Byte order writing to socket stream


<snip>
> 
> I don't know whether ACT make any guarantees about the stability of
> the wire format used by their Annex E support between releases; to be
> safe you might want to use the same release both ends.
>
GNAT implements the XDR spec, so it should be the same between releases.
 
> You'd be most unlikely to get interoperability with other Ada
> compilers (even if you could find one with Annex A support).
>
They all are required to have Annex A support.  Did you mean Annex E?

Re: Byte order writing to socket stream

[Dr. Michael Paus]

The Darkelf wrote:
> Hi, I have an Ada program with GNAT.Sockets that works fine when client
> and server are in the same architecture. The problem is when client runs
> on HP and the server on Intel, or viceversa.
> 
> It raises a STORAGE_ERROR exception, when it reads an array from the
> socket stream. I guess the problem must be the byte order, so one solution
> should be to write the size of the array(integer) and then the elements of
> the array (strings), checking the integer byte order.
> 
> Can the conversion to the net standard be done "on the fly", as I do the
> Stream'Output(stream,theArray), or it's necesary to manually output each
> element?
> 
> If so, any suggestion for checking the architecture byte order and
> ouputing it in some standard way?
> 
> May it be easier or better to just output the integer values as strings
> (Integer'Image) ?
> 
> Thanks for your opinions and suggestions.
> 
> Alvaro J. Iradier Muro

Hi,

you could download my package
http://www.ib-paus.com/downloads/AdaStreamsInNetworkByteOrder_020326.tar.gz
and use it with your program. This will automatically convert all data
into network byte order, so that you can work with mixed architectures.
This is a modified version of a standard GNAT package and so only works
with GNAT.

Hope this helps

Michael

Re: Byte order writing to socket stream

[Simon Wright]

"David C. Hoos, Sr." <david.c.hoos.sr@ada95.com> writes:

> GNAT implements the XDR spec, so it should be the same between releases.

That's good

> > You'd be most unlikely to get interoperability with other Ada
> > compilers (even if you could find one with Annex A support).
> 
> They all are required to have Annex A support.  Did you mean Annex E?

of course, stupid mistake, sorry

Re: Byte order writing to socket stream

[Robert Dewar]

"Dr. Michael Paus" <paus@ib-paus.com> wrote in message news:<3CE60CAC.7020102@ib-paus.com>...
> you could download my package ...

You could also use the GLADE version of s-stratt.ads/adb