notifications for XDI? (was Re: prototype and consequent feedback on XDI primitive)

[Giovanni Bartolomeo <giovanni.bartolomeo@uniroma2.it>]

Dear All,

reading Andy's reply I realized to haven't been so clear with my use
case; I'm sorry for this, I'll try again to better explain this idea.

The issue we're facing is that there should be some cases in which the
terminal or the device running the CLIENT side of the XDI framework might
be needed of be notified whenever certain data change. This is quite
common in telecommunications environments. 
For example, OMA XDM
(
http://www.openmobilealliance.org/release_program/docs/XDM/V1_0-20060612-A/OMA-TS-XDM_Core-V1_0-20060612-A.pdf
)

"defines the common protocol for
access and manipulation of XML documents by authorized principals. This
specification reuses the IETF XML Configuration Access Protocol
(XCAP).
XCAP defines:
• A
convention for describing elements and attributes of an XML document as a
HTTP resource, i.e., accessible via an
HTTP URI
• A
technique for using HTTP GET, PUT and DELETE methods for various document
manipulation operations (e.g.,
retrieving/adding/deleting elements/attributes, etc.)
• The
concept and structure of an XCAP Application Usage by which service or
enabler specific documents can be
described
• A
default authorization policy for accessing and manipulating
documents"

sounds familiar? Basically XDM/XCAP is roughly similar to XDI/XRI,
but with many limitations 
- it can handle just XML documents
- it doesn't define an abstract protocol and binding mechanisms
- it doesn't keep the concept of data link between documents
- ...

Though so "primitive" compared to XDI/XRI, it's the OMA
standard to be used in telco!!!

but the interesting thing is that:

"This specification also defines a technique by which changes to
such XML documents can be conveyed to an XCAP CLIENT. This reuses an
IETF-defined SIP event package by which an XDM Client subscribes to
changes to all documents that it owns."

this feature (subscription/notification) is instead missing in
XDI! Why we don't think at an extension of the current spec to support
it?

Two issues to be discussed are:
- usefulness (what you think?)
- feasibility and concrete bindings (do we need to use SIP as a concrete
binding for this purpose? Maybe we can rely on the RSS protocol?
Etc.)

(It is even trivial to say that in case of positive reactions we'll be
more than happy to take the task of writing a (more or less formal)
document to propose such an extension!)

Your comments will be welcome!!! (unfortunately I'll be out of office
next week, so time of reaction will be not elevated; however, I've just
given the kick-off :-)

Thanks,
Giovanni