[oslc-core] programmatic selection of creation factories

[Jim des Rivieres]

ref: http://open-services.net/bin/view/Main/OSLCCoreSpecDRAFT (r95, May 
27) 

Architecturally, it makes sense for a particular Service to have multiple 
occurrences of creationFactory. Take the example OSLC Blog Service as a 
concrete instance: Blog Entry and Blog Comment each have a 
creationFactory. The CreationFactory inline local resource carries a 
mandatory dc:title that helps a user in choosing among them. However, I 
don't see anything that would allow a programmatic client to make an 
analogous choice. For instance, if my client needs to create a Blog Entry, 
how would it discover which creationFactory to use? 

In general, OSLC domains must support the needs of programmatic clients as 
well as ui clients. Adding a mandatory identifier to CreationFactory would 
do the trick. The identifier could be a URI. Well-known URIs could be 
defined in the OSLC domain spec; i.e., OSLC Blog Service could declare the 
identifiers "http://open-services.net/bogus/blog/createEntry" and "
http://open-services.net/bogus/blog/createComment" for distinguishing its 
primary creation factories. All clients would be told to tolerate and 
ignore entries with identifiers that they do not recognize; this allows 
new identifiers can be introduced at any time without affecting 
programmatic clients. And the mechanism can be opened up to individual 
providers by allowing a provider to define additional provider-specific 
identifiers.

I would make the exact same argument for queryCapability, selectionDialog, 
and creationDialog as for creationFactory. Any OSLC domain that has 
multiple major resource types might decide to provide separate query 
capabilities, pickers, and creation uis for each type. Adding an 
identifier to QueryCapability and Dialog would address the needs of 
programmatic clients.

Regards, 
Jim