RE: Experimental TESTxx header usage.

[Ian B]

Hi all

I am working from:
Specification Release v.1.2 - 29th November, 2002
Document Release v.1.2-9 (Final) - 1st December, 2002

The word 'test' does not even occur in this document (according to Windows
search) so to say I was surprised doesn't really cover it! The only
reference that comes close is the following sentence in the target
addressing paragraph

Quote
A device should ignore all unknown name, value pairs included in the
header.
/Quote

In the embedded world where a firmware update means a replacement chip (in
my case on a current application anyway) these surprises are not exactly
welcome. I validate deliberately strictly and the insertion of new segments
breaks my code i.e. it will fail and ignore the message.

I validate on the fly as the characters come in down the serial line. If I
cannot tell the difference between a valid header, a valid header with
unknown segments and one which is plain not for me I cannot tell when to
give up trying to make a match. I don't have enough RAM to store the
message
body and header so on the fly was the best way to go.

Having said this if I simply say in the supporting documentation that the
unit only supports the following header format is this enough?

Have I missed something here?

Ian

>-----Original Message-----
>From: Kevin Hawkins [mailto:<a
href="/group/xAP_developer/post?postID=ysXYZviQO84gYlxF32KOMsmSOD1cFRWvYEe_4ifUjd4dEKyacvF1QzpcnX_z-qsTiYIlsWSnpH-A-1qO8KI">lists@u...</a>]
>Sent: 05 August 2003 19:52
>To: <a
href="/group/xAP_developer/post?postID=0B8H3gjPEaDFgNW1mLmF4AcdGdJsAwLntvy1LdbtHR5nNn3g446j8dP4spzzB-jyQ4sPHaQB-T73M9c-Vf2JO_8roRvqcg">xAP_developer@xxxxxxx</a>
>Subject: RE: [xAP_developer] Experimental TESTxx header usage.
>
>
>
>
> > -----Original Message-----
> > From: Stuart Booth [mailto:<a
href="/group/xAP_developer/post?postID=opB_fU2hBAGxqYEVd6SQ9X1hnunfYEOksnkbi1py2W_lL8ffJp2MAAhOmTSCFz5fNBBvTtpFp_cbmPFP5yDqjg">lists@x...</a>]
> > Sent: 05 August 2003 18:54
> > To: <a
href="/group/xAP_developer/post?postID=0B8H3gjPEaDFgNW1mLmF4AcdGdJsAwLntvy1LdbtHR5nNn3g446j8dP4spzzB-jyQ4sPHaQB-T73M9c-Vf2JO_8roRvqcg">xAP_developer@xxxxxxx</a>
> > Subject: Re: [xAP_developer] Experimental TESTxx header usage.
> >
> > On Tue, 5 Aug 2003 15:15:29 +0100, "Kevin Hawkins"
> > <<a
href="/group/xAP_developer/post?postID=ysXYZviQO84gYlxF32KOMsmSOD1cFRWvYEe_4ifUjd4dEKyacvF1QzpcnX_z-qsTiYIlsWSnpH-A-1qO8KI">lists@u...</a>>
wrote:
> >
> > > The xAP specification committee agreed in the v1.2 spec
release,
> > >(although we did not publish it), to allow the inclusion of
TEST
> > headers
> > >within xAP messages as a way of trialling suggested features.
It is
> > >perfectly permissible to use, for your own purposes - (see
below) the
> > name
> > >value pairs Test00 to Test09 in the HEADER .
> >
> > Did you mean Test99?
>
>TBH I can't remember what we agreed - I think it was Test0 to Test9 but
it
>could also have been Test00 to Test99 - and that is how I originally
wrote
>the email - that is probably why now I have two numerical digits after
the
>test. However I also reasoned that we didn't want to see a load of
>Test name
>value pairs in headers so I knocked it back down again to imply the
very
>special nature of these - I left the double 00's such that we could
expand
>it later without breaking code if need be . At the moment let's
>take it as I
>wrote it and see if that suffices.
> >
> > > Please note that the spec for
> > >xAP v1.2 says that all 'unexpected name value pairs' will be
> > gracefully
> > >ignored so this should not break anyones implementation.
>;-). All such
> > >parameters can safely be ignored as they are not part of the
spec.
> >
> > Oops. You just knew you'd get a reaction from me, didn't you?
:-)) Yes
> > folks, my framework just says "No!" when it encounters
rubbish. I
> > prefer to stop that stuff and fix it rather than casually let it
pass,
> > but in this case I'll change it.
>
>I have two views on this. Firstly that a xAP development framework
>should be
>exceptionally thorough on ensuring validity of the content of xAP
messages
>and hence shouting about such things is good. However a second view
says
>that an application will be far more resilient if it can ignore stuff
that
>it can't cope with which also allows us to do things like this. Perhaps
a
>good compromise would be to allow Test00-Test99 through but still
'flag'
>other name value pairs but not necessarily throw the teddy.
>
> >
> > >What
> > >I should also mention is that for example Test06 as used in
my
> > applications
> > >(UKUSA) is NOT to be confused with Test06 as used by say
Stuart
> > (KCSOFT). To
> > >that end you should regard my usage of Test06 as really
>"UKUSA.Test06"
> > >different to KCSOFT.Test06. Now whether you personally chose
to
> > validate
> > >this is your choice - you run the risk that someone else's
>app may use
> > the
> > >same name/value pairs for a different purpose if you don't.
> >
> > I'll add that to my ToDo list for my next batch of xAPFramework
> > updates.
>
>Again there is a double edged sword here - if we decide that we wish to
>experiment with a communal set of values eg the Test00 to Test04 pairs
then
>they shouldn't be qualified with the xAP developer name to be regarded
as
>valid - however higher ones should be. I don't know what best to
suggest
>here - maybe others have ideas - we could always say all test0x are
shared
>perhaps and start at Test99 downwards but I don't want to see loads of
>superfluous headers appearing. Maybe we need xTest00-09 and
>Test00-09 pairs.
>
>
> Kevin
>
>
>
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