Towards an Automatic Non-Deterministic Web Service Composition Platform

1. Towards an Automatic Non-Deterministic Web Service Composition Platform Markou, G. & Refanidis, I. Dept. of Applied Informatics, University of Macedonia, Greece NWeSP 2012 - Poster Session

2. Related Work Literature for Web Service Composition (WSC) suggests that: • Most widespread method of choice: AI planning • Use of standards is diverse: • OWL-S / PDDL widely used • Other standards are also common(e.g., WSMO) • Proprietary formats • Very few cases of online WSC systems • Especially, currently active • Gap in the evaluation process of the current WSC systems • Many simply evaluate their methodology on a single case study, without referring to quantitative criteria • There are a few notable exceptions, especially in the past few years NWeSP 2012 - Poster Session

3. System Goals – Functionalities (1/2) Our work: • Makes use of AI planning as our method of choice • Uses OWL-S and PDDL*, the “de facto” WS /Planning standards • Able to cope with the domain’s non-determinism • Planner-independent • Rigorous evaluation process based on • Quantitative criteria • Use case scenarios • Additional manual WSC module as a comparison • Will be the 1st online system supporting various stages of WSC *Specifically, NuPDDL NWeSP 2012 - Poster Session

4. System Goals – Functionalities (2/2) Online (Sub)Modules: • Also: • Manual WSC module • WS descriptions’ editor Translator between AI and Web Service languages Registry / Advertisement / Semantic search of Web Services Automatic WSC module NWeSP 2012 - Poster Session

5. Proposed Approach - Application Web Service details Inline operations User email registration XML Editor with syntax highlighting Semantic search alternatives Pre-defined OWL-S templates Based on Google Web Toolkit (GWT): Initial screen NWeSP 2012 - Poster Session

6. Registry • Core of the application is based on iServe • Open platform for publishing and discovering services • WSs are semantically described in OWL-S, not Minimal Service Model • Used its web-based application for • Browsing • Querying • Uploading services • Populated with version 4.0 of OWL-S Test Collection (OWL-S TC) • Made several improvements to its interface and functionality NWeSP 2012 - Poster Session

7. Translation between AI & WS Languages • AI planning language: PDDL, the de facto planning language • Specifically, NuPDDL • Compatible with PDDL2.1, retaining most of it • Capable of modeling non-deterministic action effects (one of, unknown) • WS semantic description language: OWL-S, most widely used • Heavily influenced from planning languages, such as PDDL • Partial mapping from OWL-S to PDDL exists • Part of it straightforward • Conversion of non-physical knowledge from OWL-S to PDDL problematic  Introduction of new predicate in PDDL domain? NWeSP 2012 - Poster Session

8. Automatic WSC Module • Future work – Basic directions: • WSs may fail to execute correctly, e.g., • Unavailability of an atomic WS involved in the plan • Output of its successful execution is not the expected one • Generate plans tackling the most influential and likely contingencies • Proposed solution based on contingent planning • Produce seed plan • Examine for significant/ likely points of failure • Add conditional branches • Repeat until we reach a plateau or run out of time • Re-planning module will be integrated NWeSP 2012 - Poster Session

9. Evaluation • Currently based on the manual WSC module • Modification of an open source BPMN 2.0 editor (PetalsBPM) • Making use of OWL-S TC Semantic Web Services v. 4.0 • Each scenario uses a subset of descriptions of an OWL-S TC domain • Several semantic WS descriptions added/ modified for testing purposes • Each scenario with increasing non-determinism & complexity • Quantitative criteria to be considered: • Number of Web Services considered for WSC • Preprocessing time (parsing of ontologies’ concepts, etc) • Transformation time (of WS domain to PDDL one) • Planning time (to output a successful plan) • Optimality of the outputted plans NWeSP 2012 - Poster Session

10. Use Case Scenario 1/3: Movie Database • Movie database search using a (partial) movie title • Based on Communication domain: 58 semantic WSs in total • Fully deterministic - Serialized composite WS output • Retrieve comedy films with titles similar to user input • Output: • Movie titles • Pricing information (tax-free price, recommended price, etc) Graphical workflow representing the movie database use case scenario NWeSP 2012 - Poster Session

11. Use Case Scenario 2/3: Online Bookstore • Online bookstore product purchase • User wants to purchase a book from an specific online bookstore with a preferred method of payment • Preferences regarding method of payment • Based on Education domain: 285 semantic WSs in total • Non-deterministic output • Different outcomes: • Output if book in stock: • Addition of book in shopping cart • Purchase with the specified method of payment • Output information regarding it, such as its author • No output if book not in stock Graphical workflow representing the online bookstore use case scenario NWeSP 2012 - Poster Session

12. Use Case Scenario 3/3: Camera Search • Camera search and purchase • User want to purchase an analog SLR model; willing to settle for other ones if it is not in stock • User preference towards specific model • More than one sellers exist • Based on Economy domain: 359 semantic WSs in total • Possible iteration in output Web Service • Since more than one sellers exist, if product not available at one, check another • If product not found in any of the sellers, try with other versions (digital SLR, simple compact cameras) Graphical workflow representing the camera search use case scenario NWeSP 2012 - Poster Session