Re: [dspace-tech] Collection getParentCommunityList()

Wed, 18 May 2016 15:04:14 -0700 

Hi Monika,
Those are good questions. To clarify, I'm not recommending we add a new "map collections" feature. I was just pointing out to Terry, that *at the Java API level*, DSpace has supported the idea of a Collection having multiple parents for some time. That is not a change, it's just how the Java API has worked. However, at the UI level, this feature has never been implemented because we never had a clear use case for it (and I'm not exactly sure myself why the API was built this way to begin with). 


When it comes to the REST API, we'd then have a decision. Do we let it 
act more like the Java API or do we just "hide" this feature of the Java 
API and make the REST API look more like the current UIs.  I think this 
is the basics of what Terry is asking in his #2.  I'm not sold on the 
fact that we need to let the REST API even support this feature (it's 
definitely not a high priority).



I think the real issue here is just finding a solution to 
https://jira.duraspace.org/browse/DS-2766, which is more about just 
figuring out what "parentCommunityList" was meant to do.


- Tim


On 5/18/2016 3:08 PM, Monika Mevenkamp wrote:

Right now DSpace has a conceptually clean structure, an almost perfect 
hierarchy, except where items are mapped to multiple collections.  So 
for example: it is clear what it means to show a collection in the UI. 
For a mapped item that is not necessarily true. Image styling 
different collections in different ways in a future flexible UI  - 
what style should be picked for a mapped item ? In other words - 
mapping things - means moving away from a hierarchy - means life will 
be more complicated.



My question here: Mapping Collection to multiple communities  — Is it 
worth it ?


What is the use case for mapping collections to multiple communities   ?


Can the same be achieved with solr and ‘virtual’ collections which 
could be defined as whatever matches some kind of query ?



What is the implication in terms of getting rid of the distinction 
between communities and collections ?
That is a feature I am looking forward to: we have several communities 
with a single collection with few items.



Where does that position the DSPACE model in relation to the Portland 
Data Model ?



My gut tells me to not to map collections. I don’t have a good 
overview of the wider DSPace world though.

But it would be  worthwhile discussing before hacking …


Monika
—
Monika Mevenkamp
Digital Repository Infrastructure Developer
Princeton University
Phone: 609-258-4161
Skype: mo-meven




On May 18, 2016, at 12:33 PM, Terry Brady <[email protected] 
<mailto:[email protected]>> wrote:


Tim,

Thanks for the explanation.


To implement #1, I recommend that we add the necessary hibernate 
configuration logic to recursively traverse community2community.  Who 
could advise on that change?



To implement #2, we would probably want to change the method return 
type to return a list of lists: one list for each immediate community 
parent.


Terry


On Wed, May 18, 2016 at 7:39 AM, Tim Donohue <[email protected] 
<mailto:[email protected]>> wrote:


    Hi Terry,

    Some quick answers...

    I'm not sure of the correct answer to #1 myself (Peter Dietz, did
    you create this behavior?). Since it's called a "List" though, it
    sounds to me like the behavior in DSpace 5.x is more correct
    (that the intension may be to locate the full location of the
    collection, similar to breadcrumbs).

    As for #2, the API / database has always supported the "idea" of
    a Collection existing in multiple locations (i.e. a "linked"
    Collection). However, we've never found a reason to fully build
    this out with unit tests, etc. So, it's a partially created
    concept, and it's never really been proven to "work".  In
    addition, the UIs have never supported this idea...at the UI
    level, a Collection only ever belongs to a single Community.

    So, essentially, #2 would/should be treated as a new feature. The
    groundwork is there in the API / database layer. But, it has
    never been fully built out. It'd need a volunteer to dig in and

    implement this concept so that it's actually usable in the UIs. 
    It also may require some refactoring at the REST API layer, as

    you've noted.

    - Tim

    On 5/17/2016 1:03 PM, Terry Brady wrote:

    I am investigating the following ticket:
    https://jira.duraspace.org/browse/DS-2766

    Here are my questions.
    1. In the collections endpoint, of the REST api, what is the
    intended behavior of expand=parentCommunityList?
    2. In DSpace, can a collection exist in multiple communities?

    Question 1. expand=parentCommunityList

    In DSpace5x, the expand=parentCommunityList option returns the
    full hierarchy of owing communities for a collection (all the
    way to the top level community).

    In DSpace 6x, this option returns the subcommunity that is an
    immediate parent of the collection.

    Assuming that this behavior is incorrect in DSpace 6, the
    following configuration will need to be updated to follow the
    community2community hierarchy:
    
https://github.com/DSpace/DSpace/blob/master/dspace-api/src/main/java/org/dspace/content/Collection.java#L81-L86

    Question 2: Can a collection exist in multiple communities?

    The following method in DSpace 5x could imply that a collection
    can exist in multiple communities:
    
https://github.com/DSpace/DSpace/blob/dspace-5_x/dspace-api/src/main/java/org/dspace/content/Collection.java#L1402

    But, the REST API implies that there is a single "parentCommunity".
    
https://github.com/DSpace/DSpace/blob/dspace-5_x/dspace-rest/src/main/java/org/dspace/rest/common/Collection.java#L136

    and a separate parentCommunityList
    
https://github.com/DSpace/DSpace/blob/dspace-5_x/dspace-rest/src/main/java/org/dspace/rest/common/Collection.java#L156

    What is the intended set of relationships to be supported?

    If a collection can exist in multiple communities, how should
    the REST api respond to "expand=parentCommunityList" option?

    If a collection can exist in multiple communities, how can this
    relationship be created in our UIs?

    Terry


    -- 
    Terry Brady

    Applications Programmer Analyst
    Georgetown University Library Information Technology
    https://www.library.georgetown.edu/lit/code
    425-298-5498 <tel:425-298-5498> (Seattle, WA)

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    -- 
    Tim Donohue

    Technical Lead for DSpace & DSpaceDirect
    DuraSpace.org <http://DuraSpace.org>  |DSpace.org <http://DSpace.org>  
|DSpaceDirect.org <http://DSpaceDirect.org>



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--
Terry Brady
Applications Programmer Analyst
Georgetown University Library Information Technology
https://www.library.georgetown.edu/lit/code
425-298-5498 (Seattle, WA)

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Tim Donohue
Technical Lead for DSpace & DSpaceDirect
DuraSpace.org | DSpace.org | DSpaceDirect.org

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