On Feb 8, 2008, at 2:03 PM, David Huynh wrote:

> Mark Diggory wrote:
>> A few more added comments...
>>
>> On Feb 7, 2008, at 4:44 PM, David Huynh wrote:
>>> ...
>>> here to address the case where the data at any one of those URLs is
>>> changed after the triple store is instantiated and loaded.
>>>
>> Are you using the Sesame "Context" in terms of the key you are
>> referring to above?
>>
> No, there are several separate triple stores, each instantiated and
> loaded on demand (whenever a user views an exhibit that no other users
> are currently viewing).

Certainly a valid approach that works as long as you have very  
separate "exhibits", In our case we want to provide a shared search/ 
discovery space across all our collections so it sounds like we would  
want a system that used one triple-store so that queries could be run  
across data coming from all collections, this is what Longwell is  
currently giving us.

Based on your comments to Neil and on comments Stefano and others  
have made about maybe refactoring Longwell into a "Service" and  
separate "Clients". I'd say the important use-case for those of us  
who are already running java enterprise / web-applications is that we  
would like to have flexibility and configurability on the server side  
as much as possible.  To be able to combine data-sets in one server  
and deliver multiple client configurations on that combined data.  
I.E. that managing the data and delivering a User experience on that  
are activities performed by separate but overlapping roles.

> Facets found in exhibits can actually be a lot more complicated than
> facets in Longwell instances. In Longwell, a facet can only be defined
> by a property (an RDF predicate). In Exhibit, it can be defined by an
> Exhibit expression.

That would be a very powerful capability and one I wish was present  
in Longwell, It would not only allow us greater control the inclusion  
of fields into a facet (and thus possibly improved performance) but  
also would allow us to make conditional decisions about the inclusion  
of a value based on the state of of items that have > one degree of  
separation.  To me this means less need to "shape" or "dumb down" the  
RDF going into the Longwell triple-store so that is renders in facets  
appropriately.

>>> ...
>>
>> When I think about our needs at MIT Libraries for Longwell and  
>> DSpace,
>> the data will always be local or its source very controlled on the
>> server side.  So the above cases would not be requirements for our
>> usage of the application. Though I'm sure such "dynamic loading"  
>> might
>> be of strong interest for others in the community.
>>
> Right. I think what you care about is the ability to customize the  
> site
> using just HTML rather than hacking Velocity templates, JSP pages,  
> etc.

I hope you can glean from what I've said above, that what we are  
working to accomplish is much more than theme and branding HTML/CSS,  
we are actually trying to give the user greater ability to explore a  
metadata space that is managed by more than one role...

For instance, with the following roles on a Digital Object (Admin,  
Manager, Submitter and Viewer) We may have one "Item" with statements  
made by the different users in those different roles, I.E. Users or  
Submitters may make a "Comment" about the "Item", while Managers and  
Admin would be able to change the "Item" more directly.  And even  
then, we might retain a "History" of those changes that did happen to  
the "Item".

After all these roles are creating statements in their various  
domains. We then need a expose the whole space in a way that can be  
both explored by both user choice and also have controlled access by  
users rights in the system.

> Note that a single DSpace instance might still have sub-communities  
> who
> want to customize their own front pages, or even users who want
> different pages for certain sub-collections. RDF lets users afford
> flexible data models, and Exhibit style of UI configuration lets users
> afford flexible UIs.
>
>
> Or even better, a user might want to combine some DSpace data with her
> own data (stored on her web site)...

Sure to allow more adventurous users to create their own exhibits. we  
might expose our backstage as a service that their externally  
maintained exhibit can connect to. But that well outside our current  
roadmap.

This is mostly just an exercise, our current push for a production  
prototype is Longwell focused. But its good to explore this other  
option and see if it may inform our final solution.  Anyways,  
Backstage looks like a great tool with a promising future.

Cheers,
Mark
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