Subject: RE: [Simple] Content indirection - Uploading large messages

From: Cnaan Oded <[email-masked]>
Date: Tue, 21 Jan 2003 11:50:45 +0200

Sean,

Thanks for the prompt reply. 

You may be right that the details of how large payloads are sent from the UA
to the server (in case these are not the same entities and that there is a
network based server) are outside SIMPLE scope but it seems to me that the
first hurdle SIMPLE will face would be -interoperability. If you leave this
question open for proprietary solutions, applications from different vendors
will not be able to co-exist on the same network. If you look at the WG
charter, you will find that "The IETF has committed to producing an
interoperable standard for these services ". 

The charter also refers to RFC 2778 and CPIM which require defining how
messages are sent from UAs to servers, regardless of their size.

Moreover, if you look at 3GPP requirements from SIMPLE (e.g.,
draft-niemi-simple-im-wireless-reqs-00)  they require that "The content size
MUST NOT be limited by the Instant Messaging, or message session protocols"
- SIMPLE must be able to specify how this is done.

I believe SIMPLE WG should define at least a 'default' behavior for these
cases, or refer to an external standard, such as MM1.

Oded Cnaan

-----Original Message-----
From: Sean Olson [mailto:[email-masked]]
Sent: Tuesday, January 21, 2003 9:46 AM
To: 'Cnaan Oded'; [email-masked]
Subject: RE: [Simple] Content indirection - Uploading large messages

The draft intentionally does not address the how the content is placed
on the content server to begin with.
That is a separate problem that has many disparate solutions and does
not necessarily need to be standardized.
The interesting thing about standardizing the content-indirection
mechanism is that it involves two SIP entities
and directly impacts the SIP signaling. The transfer of content, either
from the UA to the server, or between UAs
is best handled outside of SIP ... the very point of the draft.

Some important things to note:

1) The "server" does not have to be distinct from the UA. They can be
one in the same.
2) The URL does not have to be an HTTP URL, though this will be probably
be one of the more common schemes used.
   For example, an LDAP URL might very be appropriate for certain types
of content
3) HTTP is ideal for conveying meta-data about the content it carries,
but that argument is best handled outside of SIMPLE
4) It was never envisoned that MESSAGE would be used to send these large
payloads -- the entire point of content 
   indirection is to offload this to a non-SIP carrier.
5) There is nothing mutually exclusive of content-indirection and MMS.
Nor is there anything that compels one to use
   MMS for this task in the draft. It's simply outside the scope of this
draft.
6) Is there something particularly non-concrete about the draft? ;-)
7) This mechanism is not tied to any particular architecture, though
some architectures may have more pressing need for
   it than others.

cheers,
sean

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Cnaan Oded
Sent: Monday, January 20, 2003 11:05 PM
To: [email-masked]'
Subject: [Simple] Content indirection - Uploading large messages

The content-indirection draft (the latest I could find was
draft-ietf-sipping-content-indirect-02.txt) describes how messages or
notifications carry a URL in order to allow the UA to retrieve the
(usually large) content over other transports (e.g., HTTP). The draft
however does not specify how large content is uploaded from the UA to
the server.

Using HTTP per se is not sufficient for uploading messages over HTTP as
there is some meta-data that needs to be attached to the document such
as sender, recipient(s), message type etc. The MMS standard have already
solved these details in their MM1 protocol (over HTTP as well).

Note also that using the MESSAGE method is not a good practice as well
as it would generate huge load on the CSCFs (in mobile networks that
deploy IMS/MMD infrastructure), denying them from performing call
control tasks.

1. How should large messages be sent from the UA to the server? any
specific draft?
2. Does the SIMPLE WG intend to reuse the MM1 specifications or invent a
new one?
3. What's the status of this work within the SIMPLE WG? Are there any
concrete contributions?

Thanks,
Oded Cnaan
Comverse

---

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 22 Jan 2003 01:46:38 -0500

Oded,

This fits into the tricky area of architecture. SIMPLE is trying to 
develop a set of component technologies that can be combined in a 
variety of different ways to build different IM and presecne systems. 
For some functions (such as the upload of content), there are multiple 
solutions, and indeed, there exist multiple standards today, any one of 
which can be used without modification (http POST, webdav [which 
supports metadata], MMS M1).

So, can and should the IETF say that all SIMPLE systems have to use a 
single baseline mechanism for uploading the content used in indirection? 
To date, we have not attempted to do that. It is similar to mandating a 
common baseline codec for VoIP (although not as complicated of an issue 
as that), which we also have not done. Rather, it seems that other 
groups (like 3gpp), prefer to do this kind of architecture work and pick 
specific ietf protocols that are mandated for use in their area of control.

However, there is a document on our charter that discusses the 
architecture of a complete IM/presence application for consumers, which 
will discuss the various pieces of a complete system and show how they 
fit together. No doubt this document will talk about how such uploads 
are done, and will mention a specific protocol as one way to do it. That 
document is meant as informational, and so would not say that you have 
to use a particular protocol. We have not, however, discussed whether 
such a document should instead be made into a BCP, in which case it 
would be allowed to make such recommendations. Given the diversity of 
sip endpoints and systems it is not clear what the value of such 
recommendations would be.

-Jonathan R.

Cnaan Oded wrote:
> You may be right that the details of how large payloads are sent from 
> the UA to the server (in case these are not the same entities and that 
> there is a network based server) are outside SIMPLE scope but it seems 
> to me that the first hurdle SIMPLE will face would be -interoperability. 
> If you leave this question open for proprietary solutions, applications 
> from different vendors will not be able to co-exist on the same network. 
> If you look at the WG charter, you will find that "The IETF has 
> committed to producing an interoperable standard for these services ".
> 
> draft-niemi-simple-im-wireless-reqs-00)  they require that "The content 
> size MUST NOT be limited by the Instant Messaging, or message session 
> protocols" - SIMPLE must be able to specify how this is done.
> 
> I believe SIMPLE WG should define at least a 'default' behavior for 
> these cases, or refer to an external standard, such as MM1.
> 
> Oded Cnaan
> 
> 

-- 
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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