Subject: RE: [Megaco] Questions about Add

From: "Kevin Boyle" <[email-masked]>
Date: Tue, 17 Sep 2002 15:00:52 -0400

Comments inline. [KJBII]

Kevin

-----Original Message-----
From: Dinesh Pandey [mailto:[email-masked]] 
Sent: Tuesday, September 17, 2002 1:02 PM
To: [email-masked]
Cc: [email-masked]
Subject: [Megaco] Questions about Add

Hi List,
	I have a few basic doubts about the Add command. Could anyone please
answer them

1) What does the statement in section 7.2.1, para 1 mean.

"Wildcards may be used in Add, but such usage would be unusual".

I believe CHOOSE is also a wildcard and it is used very frequently in Add
commands.

[KJBII] Throughout the spec when the word "wildcards" is used, it generally
only means '*', either by itself, or as part of a partially specified
identifier.

2) How should the gateway execute the command 'Add = $', considering the
fact that the line which recommended the use of CHOOSE for creating
ephemeral terminations has been deleted.

[KJBII] I don't understand what you're asking here.  When the MGC sends A=$,
then the MG should add an ephemeral.  I don't see the link between this
command and a "line" which has been "deleted" (subtracted?).  The MGC is
responsible for cleanup, not the MG.  So the MG should execute the command
as best it can, unless there is an obvious error, such as trying to add the
ephemeral to a non-existent context.

thanks in advance,
any help would be appreciated,
Dinesh.

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---

From: "Kevin Boyle" <[email-masked]>
Date: Tue, 17 Sep 2002 16:44:38 -0400

Actually, if you look really closely at the usage of the word "wildcard"
throughout the spec, it is apparent through context that it means ALL and
not CHOOSE in many places.  I won't dispute that CHOOSE is, in fact, a
wildcard, but that's not how the spec is written.

I'm fine with making the change you are suggesting, but there needs to be a
thorough scrubbing of the spec to fix all the instances of misuse, rather
than just this one.

Kevin

-----Original Message-----
From: Terry L Anderson [mailto:[email-masked]] 
Sent: Tuesday, September 17, 2002 4:35 PM
To: Dinesh Pandey
Cc: Boyle, Kevin [NCRTP:3R90:EXCH]; [email-masked]
Subject: Re: [Megaco] Questions about Add

I cannot agree with Kevin that "wildcard" means ALL.  6.2.2 in fact states:

    A wildcarding mechanism using two types of wildcards can be used 
with TerminationIDs.  The two wildcards are ALL and CHOOSE. 

and the sentence in 7.2.1 just before the one cited by Dinesh uses the 
expression "CHOOSE wildcard..."  So I believe that the sentence:
    Wildcards may be used in an Add, but such usage would be unusual. is
confusing and should really say:
    ALL wildcards may be used in an Add, but such usage would be unusual.
This complements the previous sentence about CHOOSE rather than 
contradicting it.
Do folks think that this is a serious enough confusion to warrant an IG 
item?

(see other comments below)

Dinesh Pandey wrote:

>Thaks Kevin,
>	sorry about the confusion. I will restate the second question:
>
>In the description of Add command, RFC 3015 has a line
>
>"For an existing Termination, the TerminationID would be specific.  For 
>a Termination that does not yet exist, the TerminationID is specified 
>as CHOOSE  in the command."
>
>In the later version, (H.248.1 at the ITU website) this line has been 
>struck off. And the line inserted is
>
>"If a CHOOSE wildcard is used in the TermintationID, the  selected 
>TerminationID will be returned".
>
>
>Considering these changes (hopefully I have got them right), what 
>should be the correct behaviour of MG to a "Add=$". Should it return a 
>physical termination (it will match and it exists). Or should it look 
>into the descriptors to guess the type of termination. Or we should 
>avoid this construct and partially specify the termination ID to help 
>the MG make a decision.
>  
>
The change to remove the sentences you cite was made through the 
Implementors Guide specifically to remove the impression that CHOOSE 
cannot be used with physical terminations.  That is, CHOOSE is perfectly 
legal with either a physcial termination (to select among those in NULL) 
or with an ephemeral (creating a new termination).  As you note, MG can 
make this choice more easily if the terminationID is partially specified 
and the naming patterns for physical and ephemerals are distinct, but if 
this is NOT the case then MG must determine which type of termination 
can satisfy the enclosed descriptors.

>thanks,
>From: [email-masked] [mailto:[email-masked]]On Behalf Of 
>Kevin Boyle
>Sent: Tuesday, September 17, 2002 12:01 PM
>To: Dinesh Pandey; [email-masked]
>Subject: RE: [Megaco] Questions about Add
>
>
>Comments inline. [KJBII]
>
>Kevin
>

>I believe CHOOSE is also a wildcard and it is used very frequently in 
>Add commands.
>
>[KJBII] Throughout the spec when the word "wildcards" is used, it 
>generally only means '*', either by itself, or as part of a partially 
>specified identifier.
>
>2) How should the gateway execute the command 'Add = $', considering 
>the fact that the line which recommended the use of CHOOSE for creating 
>[KJBII] I don't understand what you're asking here.  When the MGC sends 
>A=$, then the MG should add an ephemeral.  I don't see the link between 
>this command and a "line" which has been "deleted" (subtracted?).  The 
>MGC is responsible for cleanup, not the MG.  So the MG should execute 
>the command as best it can, unless there is an obvious error, such as 
>trying to add the ephemeral to a non-existent context.
>
>thanks in advance,

-- 

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