The SDP RFC (or some related draft i read, don't remember exactly) states the purpose
for this "strictness". The reason is simplicity of the parsing engine. When the
format/order is strict, the parting can become a very trivial matter unlike
loose-formatting which requires more complex parsers. The advantage of this simplicity
is smaller code-base and easier implementation, leading to smaller foot-print, and
this ability to fit SDP implementations (whatever they are) on smaller devices.
I think this is sensible, and i wonder, why at all do we need the flexibility. In a
protocol, (by the very definition of a protocol) we agree on a set of interactions and
formats, then why don't you make all protocols (and SIP for that matter), strict in
format... i don't know... does anyone expect a human being to type in SIP messages by
hand... (i can't think of a reason other than debugging, for which too, i am sure we
use tools...). if a program is generating messages why not make it strict-format... it
still can retain its characteristics of "human-readability". I guess this loose'ness
is for historical reasons, and can be attributed to SIP's inheritance of HTTP in
general.
my 2 cents,
iv.
--
On Thu, 24 May 2001 18:15:57
M. Ranganathan wrote:
>Hello!
>
>The SDP RFC seems to impose a strict ordering in which the SDP fields may
>appear in a header. (for example, time fields must precede connection field
>per the spec). Is this ordering necessary? (it does not seem to make any
>semantic difference and I have noticed some implementations tend to order
>sdp fields in any order). The SDP RFC is also strict about spaces between
>fields, only allowing one space in most cases. Again I am wondering why.
>
>Thanks.
>Ranga
>
>--
>M. Ranganathan
>National Institute of Standards and Technology
>Advanced Networking Technologies Division
>100 Bureau Drive, Stop 8920,
>Gaithersburg, MD 20899, U.S.A.
>Tel:(301)975-3664 Fax:(301)590-0932
>
>Advanced Networking Technologies For the People!
>
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