On the aggregation problem for synthesized Web services

The paper introduces and investigates the aggregation problem for synthesized mediators of Web services (SWMs). An SWM is a deterministic finite-state transducer defined in terms of templates for component services. Upon receiving an artifact, an SWM selects a set of available services from a library to realize its templates, and invokes those services to operate on the artifact, in parallel; it produces a numeric value as output (e.g., the total price of a package) by applying synthesis rules. Given an SWM, a library and an input artifact, the aggregation problem is to find a mapping from the component templates of the SWM to available services in the library that maximizes (or minimizes) the output. As opposed to the composition syntheses of Web services, the aggregation problem aims to optimize the realization of a given mediator, to best serve the [email protected]? need. We analyze this problem, and show that its complexity depends on the underlying graph of the mediator: while it is undecidable when such graphs contain even very simple cycles, it is solvable in single-exponential time in the size of the specification (i.e., the total size of the input SWM, library and artifact) for SWMs whose underlying graphs are acyclic. We prove several results of this kind, with matching lower bounds (NP and PSPACE), and analyze restrictions that lead to polynomial-time solutions. In addition, we study the aggregation problem for nondeterministic SWMs (NSWMs). We show that the aggregation problem for NSWMs with various underlying graphs retains the same complexity as its deterministic counterparts. We also provide complexity bounds for determining whether SWMs and NSWMs terminate.

[1]  Manish Parashar,et al.  A Peer-to-Peer Approach to Web Service Discovery , 2004, World Wide Web.

[2]  Anca Muscholl,et al.  A Lower Bound on Web Services Composition , 2007, FoSSaCS.

[3]  Alin Deutsch,et al.  Verification of communicating data-driven web services , 2006, PODS '06.

[4]  Yu. V. Matijasevič.  Some Purely Mathematical Results Inspired by Mathematical Logic , 1977 .

[5]  Daniel Deutch,et al.  Optimal top-k query evaluation for weighted business processes , 2010, Proc. VLDB Endow..

[6]  Anil Nigam,et al.  Business artifacts: An approach to operational specification , 2003, IBM Syst. J..

[7]  Daniel Deutch,et al.  Evaluating TOP-K Queries over Business Processes , 2009, 2009 IEEE 25th International Conference on Data Engineering.

[8]  Mohand-Said Hacid,et al.  On automating Web services discovery , 2003, The VLDB Journal.

[9]  Alin Deutsch,et al.  Artifact systems with data dependencies and arithmetic , 2011, ICDT '11.

[10]  Piero A. Bonatti,et al.  On optimal service selection , 2005, WWW '05.

[11]  Jianwen Su,et al.  Automatic construction of simple artifact-based business processes , 2009, ICDT '09.

[12]  Huajun Chen,et al.  Extending Online Travel Agency with Adaptive Reservations , 2007, OTM Conferences.

[13]  Serge Abiteboul,et al.  Relational transducers for electronic commerce , 1998, J. Comput. Syst. Sci..

[14]  Kevin Wilkinson,et al.  QoX-driven ETL design: reducing the cost of ETL consulting engagements , 2009, SIGMOD Conference.

[15]  Jianwen Su,et al.  Towards Formal Analysis of Artifact-Centric Business Process Models , 2007, BPM.

[16]  James P. Jones.  Undecidable diophantine equations , 1980 .

[17]  Serge Abiteboul,et al.  Static analysis of active XML systems , 2008, PODS.

[18]  Oscar H. Ibarra,et al.  Automated composition of e-services: lookaheads , 2004, ICSOC '04.

[19]  Diego Calvanese,et al.  Automatic Service Composition Based on Behavioral Descriptions , 2005, Int. J. Cooperative Inf. Syst..

[20]  Marc Spielmann,et al.  Verification of relational transducers for electronic commerce , 2003, J. Comput. Syst. Sci..

[21]  Yoad Lustig,et al.  Synthesis from Component Libraries , 2009, FoSSaCS.

[22]  S. Nakajima,et al.  Verification of Web service flows with model-checking techniques , 2002, First International Symposium on Cyber Worlds, 2002. Proceedings..

[23]  Frank Neven,et al.  Complexity and composition of synthesized web services , 2008, PODS.

[24]  Diego Calvanese,et al.  Automatic Composition of Transition-based Semantic Web Services with Messaging , 2005, VLDB.

[25]  Xiang Fu,et al.  Conversation protocols: a formalism for specification and verification of reactive electronic services , 2003, Theor. Comput. Sci..

[26]  Giorgio Gambosi,et al.  Complexity and approximation: combinatorial optimization problems and their approximability properties , 1999 .

[27]  Edmund M. Clarke,et al.  Model Checking , 1999, Handbook of Automated Reasoning.

[28]  Jaideep Srivastava,et al.  A probabilistic approach to modeling and estimating the QoS of web-services-based workflows , 2007, Inf. Sci..

[29]  Alin Deutsch,et al.  Specification and verification of data-driven Web applications , 2007, J. Comput. Syst. Sci..

[30]  Marco Pistore,et al.  Process-Level Composition of Executable Web Services: "On-the-fly" Versus "Once-for-all" Composition , 2005, ESWC.

[31]  Yinghui Wu,et al.  On the aggregation problem for synthesized web services , 2010, ICDT '10.

[32]  Tao Yu,et al.  Service selection algorithms for Web services with end-to-end QoS constraints , 2004, Proceedings. IEEE International Conference on e-Commerce Technology, 2004. CEC 2004..

[33]  Diego Calvanese,et al.  ComposingWeb Services with Nondeterministic Behavior , 2006, 2006 IEEE International Conference on Web Services (ICWS'06).

[34]  Alin Deutsch,et al.  Automatic verification of data-centric business processes , 2009, ICDT '09.

[35]  Xiang Fu,et al.  Analysis of interacting BPEL web services , 2004, WWW '04.

[36]  Richard Hull,et al.  Artifact-Centric Business Process Models: Brief Survey of Research Results and Challenges , 2008, OTM Conferences.

[37]  Anne H. H. Ngu,et al.  QoS-aware middleware for Web services composition , 2004, IEEE Transactions on Software Engineering.