1. Introduction to Persistent Identifiers
Summary
Definition of persistent identifiers
Which objects – physical / digital
Proliferation of identifiers
What do identifiers allow us to do
The challenge of real persistence
Social contracts
Present, real examples
Course on persistent identifiers, Madrid (Spain)
Revolution and Web Services
Kevin Richards
Software Developer
Landcare Research
February 8th, 2012

2. Introduction
This presentation explains some standard web service protocols used when resolving persistent identifiers
This session is presented by Kevin Richards, Software Developer, at Land Research in New Zealand.

3. Summary
Resolution and Web Services
HTTP resolution
SOAP, WSDL, REST
LSID resolution
Linked Data and redirects

4. Actionability (associated services)
A desired property of Persistent Identifiers
Resolve
Get metadata
Get data
Other functions (eg generate ID)

5. HTTP Resolution Basic URI IDs
E.g.
Real example:
Uses well known, very stable HTTP protocol
HTTP GET
Headers eg content-type
Used by URI and PURL identifiers
Firebug/hurl.it demo here

6. SOAP, WSDL Simple Object Access Protocol XML based
Enables functional calls over HTTP, RPC (Remote Procedure Calls), analagous to HTTP verbs (eg GET)
Uses WSDL, Web Service Description Language, to describe functions and object types
Used by LSID resolution

7. SOAP example
<definitions xmlns:tns= <binding name="LSIDMetadataHTTPBinding" type="sns:LSIDMetadataServicePortType"> < verb="GET" /> <operation name="getMetadata"> < location="" /> <input> < </input> <output> <mime:multipartRelated> <mime:part> <mime:content part="metadata-attachment" type="application/octet-stream" /> </mime:part> </mime:multipartRelated> </output> </operation> </binding> </definitions>

8. REST Representational State Transfer
Uses built in HTTP functionality for simplicity
GET
POST
DELETE
PUT
Encouraged by Linked Data community for linked data URIs and functionality
c.f. SOAP – SOAP always uses GET and hides detail in the XML

9. LSID Resolution E.g. urn:lsid:indexfungorum.org:names:213645
3 step process
DNS lookup of LSID authority, SRV record (service record)
Get LSID functions available for the LSID
Retrieve the data, or metadata, for the LSID
lsid.indexfungorum.org:80
Authority WSDL file describing HTTP resolution endpoint
Show ipni example

10. Linked Data and Redirects
Linked data theory is that the URI is the ID for the physical object, so a redirect is done to obtain the data/metadata
303 redirect
E.g. redirects (HTTP 303 response) to
Show vapor example again, show diagram of specimen, what is on the specimen, different components, all possibly need different ids

11. Rewrites
A common way to redirect from the identifer to the location of the resource
Most web servers support it
Apache mod rewrite
IIS rewrites

12. Summary/conclusions Actionability of Persistent Identifiers
Basic HTTP resolution
SOAP, WSDL to implement RPC functionality for identifiers
REST for basic HTTP based functionality
LSID resolution
3 step process, DNS lookup, authority WSDL request, get data/metadata
Linked Data
HTTP 303 redirect to data / metadata for the physical object

13. Introduction to Persistent Identifiers
Summary
Definition of persistent identifiers
Which objects – physical / digital
Proliferation of identifiers
What do identifiers allow us to do
The challenge of real persistence
Social contracts
Present, real examples
Course on persistent identifiers, Madrid (Spain)
Revolution and Web Services
Kevin Richards
Software Developer
Landcare Research
February 8th, 2012