WSMO - revisited SWSL phone conference, Dieter Fensel Digital Enterprise Research Institute

Dieter Fensel 2 Outline The new structure and main deliverables: –WSMO Working Group –WSML Working Group –WSMX Working Group Links to SWSL –Rule language –Choreography/Orchestration language

Dieter Fensel 3 Working Groups – general overview WSMO WG WSMX WGWSML WG A Conceptual Model for SWS A Formal Language for WSMO A Rule-based Language for SW An Execution Environment for WSMO

Dieter Fensel 4 WSMO WG Web site at Chairs: Christoph Bussler and Dieter Fensel. Mailing list for group members: Mailing list for technical discussions: Contact: Activity sheet: Around 14 deliverables with defined editors and deadlines. Members: Currently 58 members. Presentations: Currently more than 45 presentations on related aspects. Current working drafts:

Dieter Fensel 5 WSMO – main deliverables Conceptual model for Semantic Web Services –WSMO Standard (D2) –WSMO Lite (D11) –WSMO Full (D12) Choreography (D14) and Orchestration (D15) –Not yet clearly defined. –Intention: use ASMs. Showcasing: WSMO Primer (D3.1) and Case Studies (D3.2) Conceptual Comparison WSMO/OWL-S (D4.1) WSMO Tutorial (D17) WSMO in DIP(D19.1), KW(D19.2) and SEKT(D19.3)

Dieter Fensel 6 WSML WG Web site at Chair: Dieter Fensel. Mailing list for group members: Mailing list for technical discussions: Contact: Activity sheet: Around 18 deliverables with defined editors and deadlines. Members: Currently 16 members. Presentations: Currently 13 presentations on related aspectshttp:// Current working drafts:

Dieter Fensel 7 WSML – main deliverables WSML language –WSML User language (D16.1) –WSML/XML (An XML Syntax for WSML) (D16.3) F-logic/XML (An XML Syntax for F-logic) (D16.2) –WSML OWL Syntax (D16.5) – not yet defined Inferencing with WSML –Inferencing support for SWS: Proof Obligations (D5.1) –Inferencing Support for Semantic Web Services: Tools for Semantic Support (D5.2) Language Evaluation and Comparison (D8) Mapping to OWL-S (D4.3) – not yet defined. Ontology Language API (D18) OWL-Lite¯ (D20)

Dieter Fensel 8 WSMX WG Web site at Chair: Christoph Bussler. Mailing list for group members: Mailing list for technical discussions: Contact: Activity sheet: Around 12 deliverables with defined editors and deadlines. Members: Currently 33 members. Current working drafts:

Dieter Fensel 9 WSMX – main deliverables WSMO Editor (D9) WSMO Registry (D10) Overview and Scope of WSMX (D13.0) –WSMX Conceptual Model (D13.1) –WSMX Execution Semantics (D13.2) –WSMX Mediation (D13.3) –WSMX Architecture (D13.4) –WSMX Implementation (D13.5) – first version expected end of June, 2004.

Dieter Fensel 10 Links to SWSL Rule language effort Choreography and orchestration language

Dieter Fensel 11 Rule language effort Six points I want to make: DL is an interesting subset of 1st order logic HL is an interesting subset of 1st order logic Full 1st order logic is an interesting language Pure logics are cumbersome tools for modeling SWRL is crap A useful rule language for the semantic web must follow a DL-minimalistic approach

Dieter Fensel 12 (1) DL is interesting because of its decidability/tractability properties spoken for the man on the street it is the fragment of logic that can be computationally explored around the existential quantifier. it is therefore worth to become standardized in OWL besides the fact that I do not like at all OWL-Lite which is an overkill, a smooth extension of RDFS would have been much more appropriate. Therefore we develope OWL-Flight (restricting OWL-Lite to DLP and extend it by RDF features).

Dieter Fensel 13 (2) HL is interesting because of its decidability/tractability properties Spoken for the man on the street it is the fragment of logic that can be computationally explored around the all quantifier without function symbols it is decidable and with minimal-model semantics function symbols, non- monotinicity of negation, and even transitive closure (an extension of first order logic) can be expressed. It is therefore worth to become standardized by W3C, however, not in a way that destroy all features of rule languages by mixing it up too much with DL type of expressions. Therefore we develope OWL-Flight (restricting OWL-Lite to DLP and extend it by rule features).

Dieter Fensel 14 (3) First order logic is interesting In oposition to DLs and HLs it provides significant more flexibility in writing down required axioms. This language is not fully mechanizable in terms of reasoning support, however, many interesting theorems can be proven and the theorem prover community has made significant progress over the last years. First order language could define the common umbrella, where DLs and HLs are sublanguages and unified. Therefore, we will redefine OWL-Full.

Dieter Fensel 15 (4) Pure logic is cumbersom Pure logics is a cumbersome tool for modeling Therefore, extensions like Flogic that allow quantification over classes and attributes are that helpful. W3C recommendations should care for this if they want to make their languages widely adopted. OWL-Flight provide these features.

Dieter Fensel 16 (5) I strongly dislike SWRL since it spoils the nice properties of rule languages for the price of defining the rule language as an extension of DLs. SWRL is meaningless since it defines a syntactical restriction of 1st order logic without any computational justification. SWRL is as undecidable and untractable as first order logic. Therefore, it is meaningless to syntactically restrict first order logic in that way.

Dieter Fensel 17 (6) A useful rule language for the semantic web must follow a different approach It should emply the full power of the HL fragment and include DL features only in case they do not harm this language type. Therefore, a HL language should be defined as an extension of RDFS and/or OWL-Lite (where OWL Lite is reduced to an actual lite subset of DL). That is the rationale underlying OWL-Flight.

Dieter Fensel 18 Choreography and orchestration Choreography is about communication Orchestration is about task decomposition Both elements require the specification of dynamics We are using Abstract State Machines as a point of departure to formalize the basic principles for these languages. And we are very eager to learn from you!