Subject: [MMUSIC] RTSP: Explicit white spacing in ABNF Syntax

From: Magnus Westerlund <[email-masked]>
Date: Fri, 25 Feb 2005 10:15:05 +0100

Hi,

I have in the latest version worked on the ABNF syntax. I added explicit 
white spacing rules and also tried running it through an ABNF validator. 
The version in the draft contains some short comings, like missing rules 
etc which is being worked to be fixed. So do note that it contains some 
known errors. However to be able to complete the work I need your input 
on a few things. So lets walk through the major changes and potential 
issues with the explicit white spacing rules.

A. It is intended that all RTSP headers has the following base syntax:
message-header  =  field-name HCOLON [ field-value ] CRLF
Where HCOLON is:
    LWS            =  [CRLF] 1*( SP / HT )
    SWS            =  [LWS] ; sep whitespace
    HCOLON         =  *( SP / HTAB ) ":" SWS

This shouldn't be a problem and follows also SIP.

B. The changing of the comma separated list, which was 1# and then was 
written as RULE 1*("," RULE), which is now RULE 1*(COMMA RULE) where 
COMMA is:
COMMA   =  SWS "," SWS ; comma

Thus is allows white spaces on both sides of the comma. This shouldn't 
be a problem either.

C. What could be more problematic is the usage of the EQUAL rule:
EQUAL   =  SWS "=" SWS ; equal
This rules has been used to replace basically all "=" in the syntax with 
the exception of the range headers.
So for example the transport header parameter:
"source" "=" host
has become
"source" EQUAL host

D. Replacement of ";" in most places with the rule:
SEMI    =  SWS ";" SWS ; semicolon

Please do consider especially in the transport header where it now would 
explicit that spacing can be inserted on either side of the ";".

Please provide comments on this or other things in the syntax.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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