LBSC 670

Information Organization

Today

• The web and automated information services

• Data, Ontologies and Web-services

• Protégé work time

Memex

Tim Berners-Lee

“data is the new killer app”

• Facebook developers kit

• Twitter API– Search, REST (CRUD), Stream

• The programmable web – Hundreds of API links

Three impacts of metadata

• Structured data use by Web-Services

• Metadata and software design

• Context-aware metadata

(1) Web-services

– “A service that is accessible by means of messages sent using standard web protocols, notations and naming conventions, including XML Protocol (or until XML protocol is standardized, SOAP).”(w3c)

– An approach to application design that uses structured data to invoke a request and subsequently returns structured data to the client

– Temp Convert: A quick example

ModelView

Controller

http://www.tonymarston.net/php-mysql/model-view-controller.html

(2) Software design

MVC RSS application

(3) Context-Aware Metadata

– Application Programming Interfaces

• A set of functions that can be called from an application program to access features of another program (studiodog)

• A means of allowing system to system data and service interchange

• Metadata in. . . .metadata out. . . .

Example - The Flickr API

• Flickr API– Types of actions– A basic RSS feed– A Search request & response

• http://api.flickr.com/services/rest/?method=flickr.photos.search&api_key=fb9f06d54e82609fce557cd3d4706a2d&tags=Terrapins

Example - API result

Flickr REST request

• A GET example:Key = value

– ?method=flickr.photos.search

– &api_key=fb9f06d54e82609fce557cd3d4706a2d

– &tags=Terrapins

– ? . . . The start of the Querystring– & . . . The Key=Value separator– = . . . Assignment operator

Web-services interoperate

• “SOA is an architectural style whose goal is to achieve loose coupling among interacting software agents”(xml.com)

– Focus on developing information services (spell-checking) rather than applications (word processing)

– Reusable, abstracted, formal, relevant, independent, structured, loosely coupled, documented, and discoverable(MSDN)

Web-Services use HTTP

• Get:– Request a resource (e.g. using a URL)

• Post:– “Submit data to be processed” (e.g. send an XML

document)

• Put– Update/Replace an existing resource

• Delete– Remove a resource

*Also Head, Trace, Options, Patch, Connect

Web-Services are RESTful

• Representational State Transfer: “Style of software architecture for distributed hypermedia” (wikipedia)

– Base URI:» http://api.flickr.com/services/rest/

– Internet Media Type (MIME!)» XML, JSON

– An operation mechanism» GET, PUT, POST, DELETE

– Capable of “Stateless” interaction

Libraries Love Web-services

• SWORD:• Simple Web-Service Offering Repository Deposit• Create, Replace, Update, Delete

• OAI / PHM• Open Archives Initiative Protocol for Metadata

Harvesting• Uses Dublin Core

• OAI / ORE• OAI / Object Reuse and Exchange• OAI for complex objects (METS)

SWORD

• Simple Web-Service Offering Repository Deposit

• Create, Replace, Update, Delete

• Atom Publishing Protocol

SWORD is METADATA

Get: Describe Post: Publish, Update Delete: Delete

OAI / PMH

• Open Archive Initiative – Protocol for Metadata Harvesting

• http://www.openarchives.org/pmh/

Oaister.worldcat.org

OAI/PMH sites

OAI/ORE

http://www.openarchives.org/ore/1.0/primer.html#Example

OAI/ORE is Ontological!

• Based on ATOM resource maps

• Encoded in RDF (Relational Data Framework)

RDF shows relationships

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#"> <contact:Person rdf:about="http://www.w3.org/People/EM/contact#me"> <contact:fullName>Eric Miller</contact:fullName> <contact:mailbox rdf:resource="mailto:em@w3.org"/> <contact:personalTitle>Dr.</contact:personalTitle> </contact:Person> </rdf:RDF>

ATOM Resource Map

• Similar to RSS

• RDF defines relationships between entries

• DC, DCTERMS describe items

http://www.openarchives.org/ore/1.0/primer.html#AtomReM

RDF can be coded in HTML

• RDFa– Half-way between HTML & RDF– Uses defined attributes to add context to

HTML elements• rel• property• typeOf

– Example

Ontological structures

• Ontological structures facilitate automation of services

• Highly structured data and knowledge create smarter services

• Context defines pathways to more information

Services | Ontologies | Data

APIs may not use ontologies

Recap: Three facets of services

• Application Programming Interfaces (flickr)– Provide standard interfaces to distributed data; may

include service or resource perspectives

• Web Services (SWORD, OAI/PMH OAI/ORE)– Include concepts of self-documentation, protocol definition,

standards focus, structured data

• Software Architecture (MVC, SOA, REST)– Focuses on decomposing business processes into discrete

services, uses concepts of documentation, standards basis but is not necessarily comparable with APIs or Web Services

The big ideas

“The next big thing is going to be what someone else does with your data”

Metadata is the language of the web - Data interoperability/automation/use

Create new uses of data, empower end-users

Open licensing agreements enable re-use of data

Remaining weeks

• Tonight – Protégé work time

• Week 12 - Dr. Jeffery Loo, Update on final projects

• Week 13 – Linked data, Ontologies due

• Week 14 – Final class