Old notes not yet moved to the above github repository

Bitstream

• name

• description

• format

• size

• download URL

• relationships

  • Bundle

  • Metadata

  • What with derived bitstreams?

    • thumbnails

      • would be best to keep the logic that determines bitstream X is the thumbnail of bitstream Y out of the UI.

      • andrea: rest is indeed better, but should we improve this in the datamodel?

      • tim: do it in rest, keep it based on the filename in dspace 7 fix it later

      • andrea: it is easy, using metadata for all

    • extracted texts

    • …

Bundle

• Name

• relationships

  • Bitstreams

  • PrimaryBitstream

    • tim: should primarybitstream be on bundle or item?

    • andrea: let’s just keep using the current implementation and keep it there

  • Item

  • Metadata

Item

• Name

• Handle

• lastModified

• isArchived

• isWithdrawn

• relationships

  • Bundle

  • Metadata

  • Collection(s)

Collection/Community

• Name

• Handle

• copyrightText

• introductoryText

• shortDescription

• sidebarText

• license

• number of items

• relationships

  • Parent(s)

  • Collections

  • Items

  • Logo

What are the “browse” endpoints?

• `/collections/65/items` or `/items?collection=65` (or `items?q=collection:65`, …)

• maybe both?

• andrea: items can be in multiple collections

• andrea: start with `/items` if we find a good use case to use `/collections/54/items` we can implement it later

General questions

Handle

• returns a reference to the proper endpoint?

• andrea: redirect, that way it can be the same for other persistent identifiers

Is there a use for a separate metadata endpoint in rest?

• where you could retrieve or query for metadata rather than items/collections

• as opposed to discovery, where the unit is the item.

• tim: wait until we identify a real use case

• andrea: don’t think so

• terry: the DSpace 6 rest query tools query on metadata from the perspective of an item.  It is possible that a metadata service could be useful as a query starting point.  Example: find all metadat with a URL to a DOI

JSON API or HAL

• Some references

  • HAL: Hypertext Application Language

  • Hypermedia as the Engine of Application State

• andrea: json api is more complete, but spring-data-rest works with HAL

• art: katharsis works with json api, but I have no experience with it

• art: and spring-data-rest looks like the bigger project so I would be ok with partial json api support due to that

How does pagination work?

• useful info

  • # results per page

  • total # of elements/pages

  • HATEOAS link to first/previous/next/last page

  • both agree

• Sorting?

  • direction

  • sort field(s)

Limiting the number of fields in the response

• profiles

  • minimal →

    • all DSO’s have this

    • for e.g. in the trail

    • fields

      • DSO name

      • id

  • list-summary

    • all

      • DSO name

      • id

    • Item specific

      • authors

      • date issued

    • for collections/communities it is identical to minimal

  • list-detailed

    • all

      • DSO name

      • id

    • collection/community specific

      • description

    • Item specific

      • authors

      • date issued

      • abstract

  • view

    • item

      • author

      • date issued

      • abstract

      • identifier.uri

    • collection/community

      • returns everything

  • omitting the profile returns everything

  • e.g. GET `/items?field-profile=list-summary`

  • andrea & tim: ok

  • andrea: should be configurable on the backend

• also retain the ability to specify a custom set of fields?

  • e.g. GET `/items?fields=handle,dc.contributor.creator,dc.identifier.doi`

  • maybe that should be: GET `/items?fields=handle&fields[metadata]=dc.contributor.creator,dc.identifier.doi` → because metadata is a relationship of item, not an attribute

  • andrea: not sure if necessary, if you have a rest endpoint that allows the creation a new profile

  • tim: let’s go with a limited set of profiles (with configurable fields), and leave configuring new profiles via the rest api until later

  • terry: I like the idea of a configurable profiles appropriate to an instance

How do we handle relationships for objects that have a lot of them?

• e.g. a collection can contain several thousand items

• but an item can also have more bitstreams that it may make sense to display at once.

• That problem is separate from regular pagination as the relation section should only return HATEOAS links, nothing else, unless you ask for it.

• However maybe we can use the same params, and first/previous/next/last links for relationships. e.g. see this forum post

  • andrea: we may avoid this problem by leaving out some relationships, for example, don’t specify all items in a collection objects

  • andrea: we can also mitigate this problem by using profiles that work on relationships as well as attributes, so you could specify a profile that leaves out certain relationships

  • tim: if all else fails we may need to look at pagination

How does inclusion of related resources work?

• often it will make sense to request related resources in the same request

• e.g. request an item, and get not only the bundles, but the bitstreams inside those bundles as well

• `include` param? e.g. GET `/items/15?include=bundles.bitstreams`

  • would return the item, it’s bundles and their bitstreams in a single response

  • multiple includes can be comma separated: GET `/collections/23?include=parents,logo`

• we’ll that the JSON API way

Every DSpace Object needs to show its location in the trail

• When showing an item page you don’t want to trigger a sequence of GETs to simply get the names of all its parent objects.

• Should we include the entire path to the root in the relationships section?

  • Maybe an includes option with a profile for the trail that only returns their name and an identifier (to be able to link to them)

    • That way we can cache the parent objects already, and just add extra information when we need it. 

• Andrea: we could also solve this by showing in the trail how you arrived there instead of where it is in the tree, but there will most likely be a use case where we need to show the item in the repository tree

Use UUIDs?

• Not easy to type or to memorize

• What if two items merge, or versioning is used. We need a persistent URI for an object.

• Maybe we should also have a shorter ID that’s only unique within one type of object?

• We could also use handles

  • In the UI I’d prefer to use `items/5123` instead of `handle/123456789/4561` → handle should redirect to the item url

  • But we could use `items/123456789/4561` or some kind of permutation or hash of the handle

  • Problem with versioned items perhaps?

• tim: we have to use UUIDs or handles. Not calling them handles may not be a bad idea