OntoWiki Application Framework & Erfurt API

Creating Knowledge out of Interlinked Data

LOD2 Presentation . 02.09.2010 . Page http://lod2.euAKSW, Universität Leipzig

Philipp Frischmuth

OntoWiki Application Framework & Erfurt API

Developing Linked Data Applications with the LOD2 Stack


http://lod2.euISSLOD 2011 . 2011-09-14 . Leipzig . Page

Semantic Wiki

OntoWiki• Differences

• Similarities

• Demo

Architecture• Erfurt

• OntoWiki AF

Use Cases

Agenda

2



Semantic Wiki

• Wiki with added semantics

• Goal: Wiki pages + background knowledge base

• Examples: Semantic MediaWiki, Rhizome, IkeWiki

• OntoWiki takes another approach


http://lod2.euISSLOD 2011 . 2011-09-14 . Leipzig . Page 4

OntoWiki

Semantic (Data-)Wiki



Conceptual Differences



Views over Articles

Resource views Wiki articles



Forms over Markup

Forms Wiki code



Why do you call that thing a Wiki?

Conceptual Similarities



© Andrew Laing

WikiWikiWeb



Wikiwiki Concepts

• Everyone can edit anything

• Content is edited in the same way as structure is

• Activity can be watched and reviewed by everyone

Ward Cunningham

10



Versioning

Everything can be undone

Philosophy: make it easy to correct mistakes

11



Vision

1.Generic data wiki for RDF models• No data model mismatch (structured vs.

unstructured)

2.Application framework:• Knowledge-intensive applications,

• Agile processes,

• Distributed user groups



Demo

http://localhost/dev/ontowiki.hg/

http://localhost/dev/ontowiki.hg/



Architecture

RDFauthor Extensions

OntoWiki Application Framework

Erfurt API

Zend Framework



Architecture



Erfurt API

Zend Framework



Zend Framework

• PHP Framework for web applications

• Extensive documentation

• Outstanding code quality

• BSD-licensed

• Flexibly usable



Zend Framework contd.

ControllerModel View

16

Provides MVC environment





• Business logic• SPARQL is here!

16







• Components• Controller's methods

are called actions• Accessible via URLs

16







• Components• Controller's methods

are called actions• Accessible via URLs

• OntoWiki_View class• Templates run in

View‘s context• View‘s variables

filled within the controller

16




Config

Controller

View

Auth Cache

Feed Log

OpenId Session Uri

XmlRpc ...




Config

Controller

View

Auth Cache

Feed Log

OpenId Session Uri

XmlRpc ...




Architecture

Erfurt API



Zend Framework



Architecture

Erfurt API



Zend Framework



Erfurt API

• Based on ZF

• Components:• Triple (Quad) Store abstraction

• Authentication + access control

• SPARQL support

• Caching

• Versioning

• ...



App

Erfurt Packages

Ac Auth

Event

Owl

Cache

Rdf

Rdfs

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



App

Erfurt Packages

Ac Auth

Event

Owl

Cache

Rdf

Rdfs

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



App package

• Contains only one class: Erfurt_App

• Base for every Erfurt application

• Singleton pattern

$config = new Zend_Config_Ini('/path/to/config.ini', 'default', true);

// initialize Erfurt application$app = Erfurt_App::start($config);

21



App package contd.

• Access Erfurt_App instance from everywhere

• Contains shortcut methods

22

$app = Erfurt_App::getInstance();

$app->authenticate();$app->addUser($username, $password, $email);$app->isActionAllowed($actionSpec);



• Grants access to required objects, e.g.:

App package contd.

23

// access the Zend_Auth instance$auth = $app->getAuth();

// access the Erfurt_Ac_Default instance$ac = $app getAc();

// access the Efurt_Store instance$store = $app->getStore();

// access the Erfurt_Cache object, if caching enabled$cache = $app->getCache();

// access the Erfurt_Log object, if logging is enabled$log = $app->getLog()



Ac AuthApp

Event

Owl

Cache

Rdf

Rdfs

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Ac AuthApp

Event

Owl

Cache

Rdf

Rdfs

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Auth & Ac packages

• RDF based authentication and access control

• Model, action (and statement) based

• Users & groups

• Built-in system ontology contains vocabulary

• Configurable

25



Auth & Ac packages contd.

26

<sioc:User rdf:about="Admin" rdfs:label="Admin"> <rdfs:comment>This is the pre-configured Admin User.</rdfs:comment> <foaf:accountName rdf:datatype="&xsd;string">Admin</foaf:accountName></sioc:User>

<sioc:Usergroup rdf:about="AdminGroup" rdfs:label="AdminGroup"> <sysont:denyModelEdit rdf:resource="&SysOnt;"/> <sysont:grantAccess rdf:resource="&SysOnt;AnyAction"/> <sysont:grantModelEdit rdf:resource="&SysOnt;AnyModel"/> <sysont:grantModelView rdf:resource="&SysOnt;AnyModel"/> <rdfs:comment>The group of all admins. If not changed, they can trigger all actions and can edit all models but the system ontology.</rdfs:comment> <sioc:has_member rdf:resource="Admin"/></sioc:Usergroup>




• Authenticate a user

• Logout

• Gather user information

• Add a new user

27

$app->authenticate('Admin', 'secretpassword');

$app->getAuth()->clearIdentity();

$user = $app->getAuth()->getIdentity();

$app->addUser($username, $password, $email);




• Model based access control

• Action based access control

28

$app->getAc()->isModelAllowed('view', $modelUri);$app->getAc()->isAnyModelAllowed('view');$app->getAc()->getAllowedModels('view');$app->getAc()->getDeniedModels('edit');

$app->getAc()->isActionAllowed('RegisterNewUser');$app->getAc()->isAnyActionAllowed();$app->getAc()->getAllowedActions();$app->getAc()->getDeniedActions();



Store

Ac AuthApp

Event

Owl

Cache

Rdf

Rdfs

Plugin

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Store

Ac AuthApp

Event

Owl

Cache

Rdf

Rdfs

Plugin

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Store package

• Developers use Erfurt_Store class

• Represents a triple (quad) store

• Abstracts different backends

• Adapter pattern

30



Zend_Db

VirtuosoMySQ

L

Oracle

SQLite

MS SQ

L

PostgreSQL

...

...

Erfurt_Store

Erfurt_App $app->getStore();

31

Store package contd.



Store package contd.

• Obtain new and existing models

• Remove models from store

• Executes the tasks of Model classes, e.g. SPARQL, adding and removing triples

• Imports and exports RDF in different formats, e.g. RDF/XML, N3, RDF/JSON

32

$app->getStore()->getModel($modelUri);$app->getStore()->getNewModel($modelUri, $baseUri, 'owl');

$app->getStore()->deleteModel($modelUri);



Owl Rdf

Rdfs

Ac AuthApp

EventCache

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Owl Rdf

Rdfs

Ac AuthApp

EventCache

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



inheritanceRdf, Rdfs & Owl packages

Erfurt_Rdf_Node

Erfurt_Rdf_Resource Erfurt_Rdf_Literal

Erfurt_Rdfs_Resource

Erfurt_Rdfs_Property Erfurt_Rdfs_Instance Erfurt_Rdfs_Class

Erfurt_Owl_Property Erfurt_ Owl_Instance Erfurt_ Owl_Class

Erfurt_Rdf_Model

Erfurt_Rdfs_Model

Erfurt_Owl_Model

34



Rdf, Rdfs & Owl packages contd.

• Add and delete statements through model class

• Simple way to execute SPARQL queries through model class

35

$model->addStatement($s, $p, $o, $options);$model->deleteStatement($s, $p, $o, $options);$model->deleteMatchingStatements($s, null, null, $options);



Sparql

Ac AuthApp

Event

Owl

Cache

Rdf

Rdfs

Plugin

Store

Syntax

Namespaces

Uri Utils

WrapperVersioning



Sparql

Ac AuthApp

Event

Owl

Cache

Rdf

Rdfs

Plugin

Store

Syntax

Namespaces

Uri Utils

WrapperVersioning



Sparql package

• Derived from rdfapi-php (RAP)

• Transforms SPARQL Queries to SQL Queries

• Result renderers

• Improvements and bug fixes

37



Sparql package contd.

• Execute a SPARQL Query

• Result is an array containing s, p and o as keys

• Values are strings

38

$model->sparqlQueryWithPlainResult('SELECT ?s ?p ?o WHERE {?s ?p ?o}');



Sparql package contd.

• More flexible way through store class

39

$queryObj = Erfurt_Sparql_SimpleQuery::initWithString('SELECT...{ ?s ?p ?o }');

$app->getStore()->sparqlQuery($queryObj, 'xml');



Event

Plugin

Ac AuthApp

Owl

Cache

Rdf

Rdfs Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Event

Plugin

Ac AuthApp

Owl

Cache

Rdf

Rdfs Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Event & Plugin packages

• Event dispatcher

• Plugin manager

• Base for Erfurt and OntoWiki plugins

41



Cache

Ac AuthApp

Event

Owl Rdf

Rdfs

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Cache

Ac AuthApp

Event

Owl Rdf

Rdfs

Plugin

Store

Syntax

Sparql

Namespaces

Uri Utils

WrapperVersioning



Cache package

• Caching of exspensive SPARQL queries

• Uses triple patterns for invalidation

• Object cache for complex/expensive results

43



• Erfurt is open source

• Github: https://github.com/AKSW/Erfurt

44

Erfurt on Github

https://github.com/AKSW/Erfurt

https://github.com/AKSW/Erfurt



Architecture



Erfurt API

Zend Framework



Architecture



Erfurt API

Zend Framework



Interfaces

• SPARQL Endpoint

• Linked Data Endpoint

• WebDAV

• REST API

• Command Line Interface

• LDAP

46



Extensibility

• Components, Plugins, Modules, Wrapper

• Views/Templates

• Themes

• Localizations

47



Access Control

• Model-based

• Action-based

• (Statement-based)

48



RDFauthor

Architecture

Extensions


Erfurt API

Zend Framework



RDFauthor

Architecture

Extensions


Erfurt API

Zend Framework



RDFa

RDFauthor

• Automatically generates forms from RDFa annoated content

• JavaScript library

• Used within OntoWiki but independent

• „Save to OntoWiki“ functionality



Architecture

ExtensionsRDFauthor


Erfurt API

Zend Framework



Architecture

ExtensionsRDFauthor


Erfurt API

Zend Framework



Components

• Provide controller

• Access via URL

• Custom views (optional)

• Map, OpenId, Community



Modules

• „Little Boxes“

• Provide additional GUI-elements

• Navigation, Login



Plugins

• Register for events

• Execution of arbitrary code

• Manipulation of input data

• Versioning, image links



Wrapper

• Generate RDF data for arbitrary resources

• Examples:

• Linked Data

• Exif

• Geodata

• Twitter



Extension mechanisms

• Components

• Modules

• Plugins

• Wrapper

• Additional: Themes, Localizations



Use Cases



SoftWiki Platform

• Collaborative requirements engineering

• OntoWiki base system

• Custom views

58





Caucasian Spiders

• Faunistic database on spiders of the Caucasus

• Taxonomy

• Localities

• 240k triples

60





Vakantieland.nl

• Dutch tourism portal

• Independent application based on Erfurt

• OntoWiki for data management





Catalogus Professorum

• Knowledge base with historical data

• Teaching staff of Universität Leipzig

• Generic OntoWiki with Virtuoso backend for data management

• Generation of HTML pages from RDF content







• OntoWiki is open source

• Google Code:

• http://code.google.com/p/ontowiki/

67

OntoWiki on Google Code

http://code.google.com/p/ontowiki/

http://code.google.com/p/ontowiki/


LOD2 Presentation . 02.09.2010 . Page http://lod2.eu

Thank you for your attention!


LOD2 Presentation . 02.09.2010 . Page http://lod2.eu

Thank you for your attention!

Questions?

Technology

OntoWiki Application Framework & Erfurt API