Using the Semantic Web to Construct an Ontology- Based Repository for Software Patterns Scott Henninger Computer Science and Engineering University of Nebraska-Lincoln

June 28, 2002 ASE PC Workshop 2 Overview Patterns as a knowledge representation and dissemination medium problem: very informal problem: no formal way to represent between patterns pattern language is lacking using Semantic Web concepts to organize patterns Combining rule-based and semantic web representations rules used to choose appropriate patterns pattern relationships make inferences on related patterns, other artifacts developer may need/want Community-based ontology construction building collective knowledge structures

June 28, 2002 ASE PC Workshop 3 Pattern Proliferation Many different types of patterns design patterns (well beyond original GOF) usability patterns (growing following) organizational patterns (projects, etc.) Alexander would be pleased original vision was that patterns are combined to construct a complete solution hence a pattern “language” Which one to use when?

June 28, 2002 ASE PC Workshop 4 Our Approach Many researchers have created usability patterns, few focus on how to make patterns usable …for software developers generalized for repeatability, reaching a widespread audience do abstract patterns really help? an unexplored empirical question Weak vs. Strong Methods [Vessey, Glass, CACM, 98] specific examples shown to be most useful for Guideline usability General hypothesis: Need to support a range of conceptual levels brings a new set of challenges How do we keep track of all those patterns? How do we find the “right” one (or more)? How do we know what the software developer’s needs are?

June 28, 2002 ASE PC Workshop 5 Our Approach (con’t) Knowledge delivery (part 1) developers don’t always know an applicable pattern exists create “applicability rules” for patterns integrate with a workflow/software process tool related to agent-based approaches Knowledge Delivery (part 2) patterns are delivered to user use semantic relationships to suggest/require other patterns where implementations exist, use them Capture experience-based knowledge capture the context in which resources are applicable part of the design and development process

June 28, 2002 ASE PC Workshop 6 BORE Building an Organizational Repository of Experiences rule-based tailoring of software development activities deliver knowledge through process

June 28, 2002 ASE PC Workshop 7 Tailoring Rules Add tasks resources to project, including patterns

June 28, 2002 ASE PC Workshop 8 Situated Process Evolution rule modification resource modification external sources of modification rule modification resource modification

June 28, 2002 ASE PC Workshop 9 Displaying Patterns

June 28, 2002 ASE PC Workshop 10 Patterns Trigger Semantic Web Search for related patterns

June 28, 2002 ASE PC Workshop 11 Semantic Web Really a concept machine interpretable representations define “semantic” content many competing languages, techniques mostly in the research stage in terms of both ontology languages and agents Semantic Web architecture

June 28, 2002 ASE PC Workshop 12 Operational View of Semantic Web Ontology Construction Tool Ontologies Annotated Web Pages XSL File Web Page Rendering Agents Meta-Data (RDFS) Decision Support System

June 28, 2002 ASE PC Workshop 13 RDF and RDFS RDF (Resource Description Framework) based on XML model for representing things (objects) on the Web RDF description is a list of triples consisting of an object (resource in RDF terminology) an attribute (property in RDF terminology) a value (a resource or text) RDFS (RDF Schema) defines meta-data primitives for creating ontologies concepts and relationships between them allows creation of a hierarchy of classes allows multiple inheritance instances of classes are placed on the Web

June 28, 2002 ASE PC Workshop 14 Example RDF File

June 28, 2002 ASE PC Workshop 15 Ontology Meta-Data (RDFS)

June 28, 2002 ASE PC Workshop 16 Instances (RDF)

June 28, 2002 ASE PC Workshop 17 Knowledge Representation Using Semantic Web to create ontologies Web-based languages for describing taxonomies, relationships people choose the appropriate class for their pattern use “semantic” tags to markup the pattern agents are created to make inferences about patterns our agent is BORE – you can create your own technology still a bit immature but usable with some effort Use the Web as a dissemination medium world-wide accessibility can facilitate group discussion especially when geographically dispersed (such as this group) open source frameworks “drawing on collective intelligence”

June 28, 2002 ASE PC Workshop 18 Adding New Instances Flyover shows RDFS attributes

June 28, 2002 ASE PC Workshop 19 Assign Values to Attributes Based on schema values interface to avoid RDF syntax…

June 28, 2002 ASE PC Workshop 20 Current Status Still in early phases of development technology and tools are not mature Beta version by end of summer seed with some existing patterns on Web author permission or pointer to book/paper invite people to add/modify patterns establish a community of usability pattern developers …that start using the Semantic Web proof-of-concept prototype for researching pattern issues analyze what patterns are needed for better coverage, etc. broaden to other pattern communities

June 28, 2002 ASE PC Workshop 21 Next Steps DAML+OIL will replace RDF using Protégé – an ontology building tool plug-in for many languages, including RDF and DAML Construct a validation process experts in usability areas validate structure and instances ala Answer Garden, Experts Exchange, etc. mechanisms for argumentation and consensus argumentation: defines context Darwinian natural selection (use in project activities)