MD Store

Introduction

The MD Store is a triple store for medatada storage and management. It is part of the process for massive batch metadata update for eSciDoc objects.

Technologies

• The triple store technology is Jena SDB (TDB doesn't support transactions)
• eSciDoc: The MD Store uses eSciDoc security management (AA)
  • It should be generic to enable other services to log in into MDstore

Interface

• The MD Store has a REST interface. Methods can be grouped in two groups, such as:
  • CRUD-based methods
  • Task-oriented methods

• CRUD-based methods
  • GET: retrieves the requested resource
  • POST: create a new resource
  • PUT: Updates a resource
  • DELETE: Deletes a resource

• Task-oriented methods (to be discussed)
  • checkOrigin - to check the difference between the properties graph in MD-Store and origin repository ?
  • updateFromOrigin - to update the properties graph from the origin (input: single resource), shall it also try to e.g. delete a metadata graph in case when this is removed from the repository origin ?
  • CQL-enabled (SPARQL enabled) - search ?

URL definition

Base URL

• Base URL of the core-service instance is appended with the URL of the new-service

    <core-service-url>/md-store 

e.g.

    http://coreservice.mpdl.mpg.de/md-store

Interface Methods URL

• For retrieval of the complete resource from the MD store (properties + all metadata record graphs)

    <base-url>/<resource-id>

e.g.

     <base-url>/escidoc:1234

• For all metadata records graph (NOTE: there can be several metadata records managed in the MD Store for a resource)

    <base-url>/<resource-id>/md-records 

e.g.

     <base-url>/escidoc:1234/md-records

• For single metadata record graph

    <base-url>/<resource-id>/md-records/md-record/<md-record-id> 

e.g.

     <base-url>/escidoc:1234/md-records/md-record/escidoc

• For properties graph

    <base-url>/<resource-id>/properties

e.g.

     <base-url>/escidoc:1234/properties

Data Model

• The MD Store defines 2 rdf graphs:
  • Metadata graphs, where metadada triples are stored
  • Property graphs with following properties:
    • context-id
    • public-status
    • lock-status
    • content-model-id
    • last-modification-date
    • created-by
    • modified-by
    • version-status
  • Note: the names of the properties are same as in eSciDoc core. However, in case when eSciDoc Core is not used, these may be set-up by the external system

Questions

• shall the interface methods understand the resource version-id?
• three alternatives could be implemented:
  • content-stream
    • is indeed for binary content only (together with the item object, must be base-64 encoded, most probably not applicable)
  • md-record - good as in this case we could deal with items, containers ... even originally considered as cumbersome, may be good approach e.g.
    • create new MD-Profile (Externally-reference
  • externally-referenced component

Metadata

Enhanced Scientific Documentation

Representational State Transfer

Create, Retrieve, Update and Delete

Common Query Language

SPARQL Protocol And RDF Query Language

Uniform Resource Locator