Technical Highlights

25th August 2011

Sebastian PetersGerman National Library of Science and Technology

DevCoreGroup

• Developer Core Group was founded in September 2010 to build a central registration infrastructure for DataCite

• Implementation of services in cooperation with DataCite’s Service Group

• Developers from BL, CDL, CISTI, TIB

• All projects are open source

• Source Code is hosted on GitHub

https://github.com/datacite

Services

Production state:

• Metadata Store (MDS, DOI/Metadata management)

Beta state:

• Metadata Export (OAI)

• Search

Future development:

• Content Negotiation

Metadata Store (MDS)

MDS is DataCite’s central infrastructure for DOI Management:

• Minting/Updating of DOIs

• Storing of metadata

Releases:

• December 2010 (public beta)

• June 1st 2011 (v2, production state)

MDS is only accessible by DataCite members (and their datacentres):

https://mds.datacite.org

Overview I

Metadata Store (MDS)

User Roles:

• Allocators (=DataCite Member) can create and manage accounts for associated datacentres

• Datacentres can mint/update DOIs and store metadata

Interfaces:

• User interface (UI)

• Programmatic interface (API)

Overview II

Metadata Store (MDS)Infrastructure

Metadata Store (MDS)

• We only accept XML

• Metadata must validate to one of DataCite Metadata Schemas (http://schema.datacite.org)

• Every single version is stored (a dataset can have multiple versions of metadata – the last one is the „real” one)

• XML is stored as it comes (no transformation)

Metadata Handling

Metadata Store (MDS)

• Restrictions per datacentre:

• List of valid domain names of landing pages

• DOI prefix(es)

• Metadata must be valid

• Periodically checking if landing pages exists (coming soon)

Quality Assurance

Metadata Store (MDS)

• Best for low volume operations

• Maintain DOIs and metadata with simple web forms

• Optimal for datacentres with only a small amount of DOIs

User Interface

Metadata Store (MDS)

• Best for bulk operations

• Can be integrated in existing infrastructures

• Simple RESTful API

• All the traffic goes via HTTPS

• All requests require HTTP Basic authentication

• API documentation: https://mds.datacite.org/static/apidoc

API

PUT /metadata/10.5072/TEST HTTP/1.1Host: mds.datacite.orgAuthorization: Basic Rk9PLkJBUjoxMjM0NTY3OA==Content-Type: application/xml;charset=UTF-8

<?xml version=“1.0“ encoding=“UTF-8“>…

Metadata Store (MDS)

•Datacentres can access MDS directly if allowed by its allocator

•Favored e.g. by BL,TIB

•Allocator can use MDS via API and develop custom frontend for datacentres•Favored e.g. by CDL

Direct Access or Custom Frontend?

Metadata Export (OAI)

• Service for 3rd parties to harvest metadata stored in the DataCite Metadata Store (MDS)

• using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH).

• Metadata formats so far: Dublin Core, DataCite Metadata Schema

• Sets for each allocator and datacentre for easy harvesting

• Beta version is available at

http://oai.datacite.org

OAI-PMH

Metadata Export (OAI)Example

Metadata Search

• Open service to search metadata stored in the DataCite Metadata Store (MDS)

• Based on Lucene Solr

• User Interface

• Complex boolean query language

• Facets (Drilldown)

• API

• Beta version available at

http://search.datacite.org

Overview

Metadata SearchHome Page

Metadata SearchResult List

Metadata SearchDrilldown

Metadata Search

• Special form for advanced search

• We also support complex lucene query syntax, e.g.

• title:laser OR subject:laser

• publicationYear:[1990 TO 1995]

Advanced Search

Content Negotiation for DOIs

• Service for getting metadata of a DOI

• Uses DOI proxy (http://dx.doi.org)

• First implemented by CNRI and CrossRef:

“but the beauty of the setup is that from now on, any DOI registration agency can enable content negotiation for their constituencies as well. DataCite- we're looking at you ;-) .”

(Geoffrey Bilder on CrossTech blog)

• Prototype (for some selective prefixes) is running at

http://data.datacite.org

Inspired By CrossRef

Content Negotiation for DOIs

• HTTP Content Negotiation is a simple way for HTTP clients to get different representations of the same resource.

• Client only needs to know the internet media type (MIME type)

• We will expose metadata in DataCite Format viaapplication/x-datacite+xml

• Other media types will follow (Dublin Core, RDF, BibTex, etc.)

• Could also be used to link directly to the dataset

What is Conneg?

Getting Metadata:

GET /10.5072/TEST HTTP/1.1Host: dx.doi.orgAccept: application/x-datacite+xml

Resolving DOI:

GET /10.5072/TEST HTTP/1.1Host: dx.doi.org

Thank you for your attention!