Managing ontology versions with a distributed blackboard architecture Ernesto Compatangelo, Wamberto Vasconcelos and Bruce Scharlau

AI 2004 Compatangelo, Vasconcelos and Scharlau Overview zVersioning Context zArchitecture zFramework zRepresentation zScenarios zConclusions and future work

AI 2004 Compatangelo, Vasconcelos and Scharlau Software versioning zConcurrent versioning system (CVS) and Subversion used for software engineering compare versions line-by-line zDoesnt work in ontologies where there are multiple ways to write the ontology zNeed something else…

AI 2004 Compatangelo, Vasconcelos and Scharlau Context of ontology versioning z Ontology versioning y supports the evolution of a conceptualisation y formally represents this evolution as a set of transformations between ontology versions y involves recording, analysing, deriving, classifying, and combining changes between ontology versions y often occurs in a distributed environment

AI 2004 Compatangelo, Vasconcelos and Scharlau Why ontology versioning? z Keeping track of ontology versions is useful to y evaluate the different context- dependent consequences of changes on the knowledge repositories and y query the knowledge-based applications that use the evolving ontology y ensure that the applications using the ontology are not broken by changes

AI 2004 Compatangelo, Vasconcelos and Scharlau What else? zNeed to keep track of more than ontology versioning information zAlso need… yProfiling team members xHow often and how much each member contributes xQuality of contributions yRecording responsibilities – who did what yRecording justification for changes

AI 2004 Compatangelo, Vasconcelos and Scharlau Architecture JavaSpace Reports Notification Other functions Other functions Changes Forminteraction Forminteraction Distillchanges Distillchanges Alternativeviews Alternativeviews Ontology Editors Ontology Editors Web Browsers Web Browsers Reasoning Tools Reasoning Tools Visualisation Tools Visualisation Tools Agent 1 Agent 2 Agent n …. Blackboard

AI 2004 Compatangelo, Vasconcelos and Scharlau ConcepTool Example Local Filespace Local Filespace

AI 2004 Compatangelo, Vasconcelos and Scharlau Framework: I-MOMS and OVM zInferential Multiple Ontology Management System (I-MOMS) yencompasses ontology elicitation, modelling, validation, interoperability, integration, and versioning in the semantic grid zOntology Versioning Manifold (OVM) yEvolutionary history documentation of each concept across different ontology versions yReconstruction of each concept in the ontology using the versioning information yEnable virtual versioning hierarchy with set of overlapping ontologies

AI 2004 Compatangelo, Vasconcelos and Scharlau Representation of changes zGiven an ontology we want to represent the changes at the end of the editing session that end in the variant ontology version [i,1] zResult of each operation f k must be a variant ontology [i,1] of [i] zAllow for the reconstruction of development history of the ontology from course-grain to fine-grain

AI 2004 Compatangelo, Vasconcelos and Scharlau Versioning Scenarios Rewriting rules yCreation of a concept yRenaming of a concept Addition of attribute/value pair to a concept zThe rewriting rules should accommodate means for user-interaction, allowing engineers to experiment with distinct combinations. A graph may be better represention as different sequences of operations may result in the same ontology.

AI 2004 Compatangelo, Vasconcelos and Scharlau Example - Various paths

AI 2004 Compatangelo, Vasconcelos and Scharlau Conclusions and the road ahead zOntology building demands tools that support distributed team work zOurs is a knowledge-rich approach to versioning deployed in an open, pluggable, lightweight and scalable architecture zThe justifications of design and changes allows for formal reasoning about the design activity

AI 2004 Compatangelo, Vasconcelos and Scharlau Thanks for your time. Any questions?

AI 2004 Compatangelo, Vasconcelos and Scharlau Related versioning work zThere are yFrameworks for versioning evolution yModelling and representing change details ySpecifying change operations and their implications yDeveloping algorithms and tools for comparing versions zTools to do each (and some) of these, but nothing to do all of these zNone of the others address the reasoning with and about the versioning space issue

AI 2004 Compatangelo, Vasconcelos and Scharlau Architecture Features zAgents ymonitor the space yprepare reports ysearch for components zOntology editors yperform changes in the versioning space and yadd extra knowledge on the operations carried out zWeb browsers yinteract with the shared space via forms zReasoners ydistill complex ontology changes from a log of yediting changes, including ystructural, and lexical differences between ontology versions zVisualisation tools zallow the inspection and retrieval of the shared space along different dimensions and in alternative formats

AI 2004 Compatangelo, Vasconcelos and Scharlau JavaSpaces: what are they? zJavaSpaces applications: collections of processes cooperating by exchanging objects using one or more spaces

AI 2004 Compatangelo, Vasconcelos and Scharlau JavaSpaces: what are they? zJava implementation of space-based distributed computing zImplementation consists of: ySpaces yPrimitive operations to allow processes to use spaces zWhat is a space? yShared, network-accessible repository for objects zWhat are the operations? yMeans to store & exchange objects in spaces zNo direct (point-to-point) communication

AI 2004 Compatangelo, Vasconcelos and Scharlau JavaSpaces: what are they? zProcesses perform simple operations to: yWrite objects onto space yTake (remove) objects from space yRead (copy) objects from space zWhen taking/reading objects, processes yUse a simple lookup to find objects yMay be blocked if no such object exists (if we want…) zIn order to modify an object, processes must yRemove object from space, yAlter it and then yReinsert it onto space

AI 2004 Compatangelo, Vasconcelos and Scharlau JavaSpaces: what are they? zSpace-based applications require yDistributed data structures and yDistributed protocols zDistributed data structures: yMultiple objects stored in different spaces yData structures held in a space can be concurrently accessed and modified by different processes zDistributed protocols: yDefine the way processes share and modify data structures in a coordinated way.

AI 2004 Compatangelo, Vasconcelos and Scharlau JavaSpaces: what are they? zDistributed protocols are loosely coupled: ySenders and receivers do not need to know each other ySenders and receivers do not need to be active simultaneously zUsing a shared space, we write an object with the expectation that ySomeone, Sometime, Somewhere Will take the object and use it according to the distributed protocol zDesigners/Programmers yDefine distribute protocol AND yEnsure that processes follow it

AI 2004 Compatangelo, Vasconcelos and Scharlau JavaSpaces: key features zSpaces are shared: yNetwork-accessible shared memories yMany remote processes can interact concurrently ySpace itself handles concurrent accesses zSpaces are persistent: yReliable storage for objects. yOnce stored in a space, an object will stay there until a process removes it. yProcesses may specify a time after which the object will be destroyed.

AI 2004 Compatangelo, Vasconcelos and Scharlau JavaSpaces: key features zSpaces are associative: yObjects are located via associative lookups yWe use a template to match against objects. A template is an object with some/all of its fields set to specific values or null (wildcard). zSpaces are transactionally secure: yAn operation on a space is an atomic affair zSpaces allow us to exchange executable content: yWhen a process gets an object from a space a local copy is created; yAs a local object, we can modify its public fields and invoke its methods; yWe can extend the behaviour of our applications

AI 2004 Compatangelo, Vasconcelos and Scharlau Architecture JavaSpace Reports Notification Other functions Other functions Changes Forminteraction Forminteraction Distillchanges Distillchanges Alternativeviews Alternativeviews