Hi Alan,
Because you are running the AIP import in "-s" mode, this acts as a *new
submission* and will assign *new handles* to Items, Collections and
Communities.
The reason this is important to note is that in AIPs, *handles are the
unique identifier used to maintain relationships between objects*.
Let's repeat that: *In AIPs, handles are the unique identifier used to
maintain relationships between objects* :)
What this means is the following:
* Suppose you a "DSpaceInstance#1" containing an Item with Handle
"1234/10" which is in a Collection with Handle "1234/2" and mapped to
another Collection with Handle "1234/5"
* When you export this Item to an AIP, it with generate an AIP named
"ITEM@1234/10.zip". Instead this AIP (in a METS file) will be recorded
that this Item is "owned" by a Collection with Handle "1234/2" and
mapped to a Collection with Handle "1234/5".
* When you *import* this Item's AIP into another DSpace
("DSpaceInstance#2") using "-s" option, here's what happens. By default,
"-s" will import the Item to whatever Collection you specify (i.e. it
ignores the "parent object handle" specified in the AIP). So, the Item
will end up under the Collection you expect.
* HOWEVER, Item Mappings are an entirely different issue. When it comes
to Item Mappings, DSpace will just map the Item to the Collection(s)
specified in the AIP, as unfortunately DSpace has no way to determine if
the Handle of the "mapped" Collections has changed or not. DSpace also
has no way to 100% verify that the Collection with Handle "1234/5" in
"DSpaceInstance#2" is the SAME AS the Collection with Handle "1234/5" in
"DSpaceInstance#1".
So, the problem here may be that you are using the "-s" option to import
Communities/Collections. When using the -s option, DSpace is going to
assign a *brand new handle* to each Community/Collection during the
import process (unless you specify "--o ignoreHandle=true" to keep the
existing handle). Although DSpace will retain the hierarchy of newly
submitted Communities/Collections/Items (because the "--o
ignoreParent=true" is default), it may have difficulty in maintaining
the *Item Mappings* between collections (as mappings are always recorded
by Collection Handle, and Collection Handles may have changed when you
moved this content between DSpace instances).
This is one of the big differences between "-r" (restore) and "-s"
(submit) modes. The former (-r) ensures that Handles are
maintained/restored (therefore item mappings & everything else will be
restored properly). The latter (-s) specifically assigns *new Handles*
to all objects. This has the potential to cause issues with Item
Mapping, though a Community->Collection->Item hierarchy will work fine.
Not sure if that helps, but I think this is what you are seeing. It's
essentially a "known issue", because unfortunately the only "unique
external identifier" DSpace has is Handles. Therefore, when an object's
Handle *changes*, attempting to maintain all mappings becomes extremely
complex.
- Tim
On 1/22/2014 10:04 AM, Alan Orth wrote:
> Hi,
>
> I'm trying to migrate a community hierarchy between two different DSpace
> instances using AIP Import (in -s mode), and I'm seeing unpredictable
> behavior with mapped items.
>
> I've been trying to identify a pattern, but so far have only identified
> the following cases:
>
> * Some item views show only some of the collections they are mapped
> to, but if you navigate to another collection you can see it there
> * Some items are mapped to incorrect collections entirely
>
> Has anyone else noticed this? Both DSpaces are 3.1 with PostgreSQL 9.1,
> on Linux of course.
>
> Thanks,
>
> --
> Alan Orth
> [email protected]
> http://alaninkenya.org
> http://mjanja.co.ke
> "I have always wished for my computer to be as easy to use as my telephone;
> my wish has come true because I can no longer figure out how to use my
> telephone." -Bjarne Stroustrup, inventor of C++
> GPG Public Key: 0xf92c4bd91084bb5de14e20be9470dd588dd1026c
>
>
>
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