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Re: [higgins-dev] new IdASRegistry

Yes, if multiple factories are used for one context, they must share one configuration. I don't see any easy way of having multiple configurations for one context.

However, if it is impractical to agree on some format for the config, it could simply be the union what the individual factories need. Factory A could ignore the config elements of factory B, and vice versa, hoping that there are no name collisions :)

Also, just to remind of this, it IS possible to have factory-specific configuration in the registry XRDS file. However, this configuration is only fed into the context factories when they are first instantiated and has nothing to do with instantiating/opening/configuring contexts.

Markus

On 8/7/07, Jim Sermersheim <jimse@xxxxxxxxxx> wrote:
I agree that this is an issue.  As long as the definition of a ContextId (see http://wiki.eclipse.org/ContextId ) is in accordance with Greg's #2 below (which it is), then we'll need to ensure that the context-specific config info is standardized.
 
Another option is to say that a ContextId is only used against a single context factory to produce a context.
 
A middle-ground options is to say that yes, multiple factories can be used to instatiate a context from a given ContextId, but in those cases, some bilateral agreement on the format/language of the context config must occur between those multiple factories.
 
Jim

>>> Greg Byrd <gbyrd@xxxxxxxx> 8/7/07 12:59 PM >>>

OK, I'm trying to think this through.   See if you agree with the following:

(1) We want a Context, as identified by a particular ContextID, to be this abstract notion of a particular set of identity information (DigitalSubjects and their relationships).

(2) A particular context provider (via a particular ContextFactory) implements this abstraction in a particular concrete way.  The details of this concrete implementation can differ, even if the abstract Context is the same -- e.g., residents of Boston.  (Even if the underlying data store is LDAP, even with the same HOWL-based data model, different CPs have different implementations of how that LDAP directory is exposed via IdAS.)

(3) A particular ContextFactory needs some configuration information to provide access to (open/create) a Context.  The details of this configuration information can be different from factory to factory, depending on the implementation.  At the very least, there's been no attempt to standardize this information across CPs, has there?

(4) So, what goes in the XRDS file for a particular context?  If the info is factory-specific, then it doesn't make sense (perhaps) to allow multiple factories to be named.  If it's not factory-specific, then who decide what configuration stuff is specified for a particular context, and how is this published, so that someone else can write a CP that consumes this information?


It seems to me that if we expect multiple ContextFactories to be able to create a Context, then we need to standardize the language used to describe how the Context is configured.  I'm talking about really detailed, mundane stuff -- like the names of settings, etc.  The factory has to consume this stuff in order to do createContext().

...Greg



Paul Trevithick wrote:

I'd rather not have the IdAS registry remember the binding.  As long as IdAS consumer can, for a given ContextId, (a) get the list of potential factories and (b) choose which one it wishes to use, that should be good enough.

 



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