Subject: RE: [Megaco] 2.5 coinciding types: SigParameter, EventParameter, PropertyParm

From: "Kevin Boyle" <[email-masked]>
Date: Thu, 2 Feb 2006 13:06:42 -0500

Parameters for events and parameters for signals are independent of each
other and the property space.  You cannot define a parameter such that
it applies to signals, events and is a property.

The fact that they are coincidental in syntax does NOT make them
coincidental in actual definition.  Further, there are special parms
that are defined in the base protocol that fall into some of the
categories.  These special items (Embedded Events/Signals Descriptor,
Duration, etc.) are specific to the construct they are defined in
(Embedded descriptors are specific to events, duration is specific to
signals, etc.).  Therefore, there no a way to merge these constructs
into a single construct.

Kevin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of [email-masked]
Sent: Thursday, February 02, 2006 6:29 AM
To: [email-masked]
Subject: [Megaco] 2.5 coinciding types: SigParameter,
EventParameter,PropertyParm

Hi,

I see in H.248 Version 2:05/2002 that the 3 types mentioned above are
practically the same (the only difference is that name in PropertyParm
is of size 4 and that the value's type is not denoted as Value in one
case...).

What is the reason behind this? Are there only "historical reasons"? Why
don't we have one type (e.g. GenericParam) for all of these? According
to my current view this approach (using 3 coinciding types) is rather
confusing and makes all implementation for the protocol less
straightforward. What do you think? If there are no "real" reasons
behind the separation: would it be possible somehow in the (long) future
to merge these types into one?

Are there other similarly coinciding types?

Thanks in advance,
Peter Tury

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From: [email-masked]
Date: Fri, 3 Feb 2006 10:46:46 +0100

Hi,

thanks for the answer!

In fact I still think this coincidence should be represented via the
usage of the same types. Let me  clarify my reasons.

>it applies to signals, events and is a property.

Of course I don't want to: this would mean that the
semantic/interpretation of the actual values would be the same, and this
is obviously not the case.

In my opinion this is a syntax issue and has nothing to do with semantic
problems. Here (in the ASN.1/ABNF part of the standard) we practically
define types. Types determines the "format" of the data they can be used
for. If the format of these data are the same and this is intentional
then the same types should be used.

In fact, they really have to be handled (but not interpreted!) in the
same way. This can be articulated in an unambiguous way if we use the
same types.

E.g. let's think about human names: they have the same format (thus same
type should be used for them in a standard) even if we have male and
female names, and they are independent of each other and we cannot
"define" a name such that is applies equally to males and females (...);
"the fact that they are coincidental in syntax does NOT make them
coincidental in actual definition", but there format (and thus their
type) should be the same. E.g. because they have to be handled in the
same way: we have to take the same steps if we want to extract e.g. the
given name. Similarly: we have to take the same steps if we want to
determine e.g. the value of an eventparameter or the value of a
propertyparm. When we have its value, we have to interpret them
independently, of course.

>Further, there are special parms
>signals, etc.).

It seems you misunderstood me: I "proposed" the merging of items (types)
one level below: not signal's, but sigParList's type with evParList's
type (and not with RequestedEvent's type)...

Am I wrong?

Thanks again very much in advance,
P

>From: ext Kevin Boyle [mailto:[email-masked]] 
>Sent: Thursday, February 02, 2006 19:07
>To: Tury Peter (Nokia-NET/Budapest); [email-masked]
>Subject: RE: [Megaco] 2.5 coinciding types: SigParameter,