MeGaCo PropertyParm formatting question

Hakan Mattsson <>
Wed Aug 21 13:35:29 CEST 2002


On Wed, 21 Aug 2002, Peter-Henry Mander wrote:

pete> Hello everyone,
pete> 
pete> I've learnt and been using Erlang over the last couple of weeks to build 
pete> a Gateway Emulator for testing purposes. So far it's been a successful 
pete> project, with good results in staggeringly little time. 

Great!

Pete> So what do I need to do for each case of extraInfo?

Nothing. In other contexts where extraInfo is allowed, you
should use it exactly as you have done.

You can however not use extraInfo in the context of local
and remote descriptors. At least not when using the textual
encoding. But I do not think that it should be used in the
binary encoding either (even if it not is explicitly prohibited
in the RFC).

According to the RFC, the ABNF representation of local and remote
descriptors are limited to be a plain octet string containing SDP
info. This seems fair enough.

Unfortunately the corresponding ASN.1 representation (in the RFC) is
mapped to the more generic PropertyParm structure. This means that it
it seems to be syntactically correct to use the extraInfo stuff when
using ASN.1, while it is has no corresponding representation in ABNF.

Even if our protocol stack allows the usage of extraInfo for the ASN.1 
encoding, I suggest that you submit a question on the Megaco list before
you use the extraInfo stuff in the context of local and remote descriptors.
I doubt that it is allowed.

/Håkan









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