Subject: Washington Issue 10 - Whitespace in SDP

From: Brian Rosen <[email-masked]>
Date: Mon, 15 Nov 1999 14:29:33 -0500

A number of issues were raised in the Washington meeting that
were "send to the list".  This is one of these issues, with the
problem and my suggested fix.

Problem
SDP does not allow leading whitespace.  Megaco does.  Looking
at the examples, you can see why it might be good to allow
leading whitespace in SDP

Proposal
Allow leading whitespace in SDP

Brian

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From: Shyamal Prasad <[email-masked]>
Date: Mon, 15 Nov 1999 13:38:49 -0600

Writing a SDP parser was one of the few pleasures I've had when
implementing text based protocols (and I'm a text bigot at that
too!). SDP is a good example of how one can design a text protocol
that is easy to read, easy to parse efficiently, and show the binary
bigots why text is the way to go forward. So why exactly do we want to
mess it up?

Looking at implementation experience of SDP parsers in traditional
compiled languages like C, it might be a good idea not to allow
leading white space in SDP messages.

All this IMHO (and tounge in cheek, of course ;-)

Cheers!
Shyamal

    "Brian" == Brian Rosen <[email-masked]> writes:

    Brian> A number of issues were raised in the Washington meeting
    Brian> that were "send to the list".  This is one of these issues,
    Brian> with the problem and my suggested fix.

    Brian> Problem SDP does not allow leading whitespace.  Megaco
    Brian> does.  Looking at the examples, you can see why it might be
    Brian> good to allow leading whitespace in SDP

    Brian> Proposal Allow leading whitespace in SDP

    Brian> Brian

---

From: Abdallah Rayhan <[email-masked]>
Date: Tue, 16 Nov 1999 13:30:25 -0500

I dont think this matter is an issue for us because our ABNF takes care
of it.

LBRKT = LWSP %x7B LWSP
RBRKT = LWSP %x7D LWSP

Hence, anything that is between "{" and SDP is consumed by LWSP
in LBRKT and anything between SDP and "}" is consumed by LWSP
in RBRKT.

All we should care about is for the SDP block to be RFC2327
compliant. Spaces before or after are not a problem.

Abdallah Rayhan