[Standards] Pubsub extension idea

Brett Zamir brettz9 at yahoo.com
Fri Dec 26 05:35:35 UTC 2008


Along the lines of how Data Forms types and Data Forms Validation can 
influence display of forms, I'd like to see some standard way in which 
Pubsub payloads could be similarly extensible, not only by allowing 
different namespaces (as is now allowable within Atom extension elements 
or for a wholly different root namespace), but by some extensible 
standardization which could give more hints than either of these at 
input and display type. Data Forms & Data Forms validation might 
themselves be used as a payload, but I can see a need for more types 
targeting display of different types of GUI elements. For example, it 
would be nice to know whether an uploaded file (which could use 
sipub:file-transfer as the datatype) should be suggested as an image, an 
iframe, a link for download, etc.. This would allow:

1) As with DF, a uniform way to know how to display payloads
2) Allow semantic extensibility while also being able to suggest a 
display mode when the semantic namespace is not recognized.

However, even with DF + DFV, there would need to be some way to indicate 
that DFV was also supported (if these are kept as separate specs), since 
Pubsub only allows for specification of one payload namespace--this 
might, I imagine, be done by requiring that both namespaces be supported 
if used as a Pubsub payload or, even better, by adding an option to 
Pubsub to indicate additional sub-namespace(s) that are required/supported).

While Atom is extensible, there is no way to make a meta-data query to 
know what inner namespaces are supported (or to specify which ones 
during Node configuration), so DF+DFV (or any other option) is not so 
suitable as an Atom extension. DF + DFV could be used as the root, even 
indicating Atom namespaces+type within <field var>, but again, there 
would be no way to detect ahead of time which semantic namespaces (such 
as Atom) were being used within DF+DFV without first accepting the payload.

Thus I'd like to suggest
1) a list-multi option be added to Pubsub to allow additional supported 
sub-namespaces to be indicated (whatever the top-level namespace).
2) Data Forms and DFV be extended to offer greater specificity in types 
suggesting various input and display elements. (Maybe some existing GUI 
kit could be used as the basis for such a namespace.)

Also, I think it might be nice to have an option to be able to indicate 
whether the namespaces (or subnamespaces) were required for proper 
viewing, or just supplementary.


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