Web service behaviour is currently specified in a mixture of ways, often using methods that are only partially complete. These range from static functional specifications, based on interfaces in WSDL and preconditions in RIF, to business process simulations using executable process-based models such as BPEL, to detailed quality of service (QoS) agreements laid down in a service level agreement (SLA). This paper recognises that something similar to a SLA is required at the higher business level to govern the contract between service producers, brokers and consumers. We call this a business level agreement (BLA) and within this framework, seek to unify disparate aspects of functional specification, QoS and run-time verification. We propose that the method for validating a web service with respect to its advertised BLA should be based on run-time service monitoring. This is a position paper towards defining these goals

A. Lazovik

D. Ameller

F. Barbon

H. Kreger

J. Simmonds

K. Mahbub

L. Baresi

S. Eilenberg

Y. Gan

Z. Li

English

Bratanis, K.

Dranidis, D.

Simons, A.J. H.

White Rose Research Online

promoting access to White Rose research papers    White Rose Research Online eprints@whiterose.ac.uk    Universities of Leeds, Sheffield and York http://eprints.whiterose.ac.uk/    This is an author produced version of a paper published in Lecture Notes in Computer Science.    White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/43422     Published paper  Bratanis, K., Dranidis, D., Simons, A.J.H. (2010) Towards run-time monitoring of web services conformance to business-level agreements, In; Bottaci, L., Fraser, G. (ed.) Testing – Practice and Research Techniques, 5th International Academic and Industrial Conference, TAIC PART Sept. 3rd - 5th 2010, Windsor, UK, Lecture Notes in Computer Science, (6303) http://dx.doi.org/10.1007/978-3-642-15585-7_22     Towards Run-time Monitoring of Web ServicesConformance to Business-Level AgreementsKonstantinos Bratanis1, Dimitris Dranidis2, and Anthony J.H. Simons31 South East European Research Centre (SEERC),Research Centre of the University of Sheffield and CITY College,Mitropoleos 17, 54624,Thessaloniki, Greece,kobratanis@seerc.org,http://www.seerc.org/2 Computer Science Department, CITY College,International Faculty of the University of Sheffield,Tsimiski 13, 54624, Thessaloniki, Greece,dranidis@city.academic.gr,http://www.city.academic.gr/3 Department of Computer Science, University of Sheffield,Regent Court, 211 Portobello Street, Sheffield S1 4DP, UK,a.simons@dcs.shef.ac.uk,http://www.sheffield.ac.uk/Abstract. Web service behaviour is currently specified in a mixture ofways, often using methods that are only partially complete. These rangefrom static functional specifications, based on interfaces in WSDL andpreconditions in RIF, to business process simulations using executableprocess-based models such as BPEL, to detailed quality of service (QoS)agreements laid down in a service level agreement (SLA). This paperrecognises that something similar to a SLA is required at the higherbusiness level to govern the contract between service producers, brokersand consumers. We call this a business level agreement (BLA) and withinthis framework, seek to unify disparate aspects of functional specifica-tion, QoS and run-time verification. We propose that the method forvalidating a web service with respect to its advertised BLA should bebased on run-time service monitoring. This is a position paper towardsdefining these goals.Key words: run-time verification, business-level agreements, QoS, Webservices, Stream X-Machines1 Business-Level AgreementWeb services enable the outsourcing of business processes to different serviceproviders. Each provider may offer a similar service with different behaviour, i.e.different functional or non-functional characteristics. Before the service provisionthe service provider and the service consumer will have to agree on the concretebehaviour of the service.2 Konstantinos Bratanis, Dimitris Dranidis, and Anthony J.H. SimonsThe functional characteristics concern the implementation of the individualoperations in a Web service and the allowed sequence of messages. For examplehow a payment is being handled and what are the preconditions for performinga payment. The non-functional characteristics concern quality attributes froma technical perspective such as accessibility, responsiveness and throughput, aswell as quality attributes from a business perspective such as orders fulfilled ina day and payments handled per hour. For the quality of the technical aspectof the service provisioning a service-level agreement (SLA) is often established.For the business aspect, however, we believe that another type of agreementis required that captures both the functional and the non-functional businesscharacteristics of the service provisioning.Inspired from what already exists in the real business world, we call this newtype of agreement a business-level agreement (BLA). Another inspiration for theterm is [14], according to whom, the term BLA describes an agreement betweentwo business partners who will be participating in business processes using Webservices. To clarify the need and the contents of BLA, we discuss an example inthe next paragraph.As an example, in a pharmaceutical industry pharmacies order the medicalsupplies from a pharmaceutical company. The pharmaceutical company uses athird-party logistics (3PL) provider to handle the inventory and the shipment ofmedical supplies. A pharmacy places an order using the OrderManagmentServiceprovided by the pharmaceutical company. After the necessary validations and inorder for the ordered items to be shipped to the pharmacy, the pharmaceuticalcompany uses the WarehouseService provided by the 3PL.Both the pharmaceutical company and 3PL have signed BLA that states thefollowing: (i) In the case that for a particular item, contained in the pharmacy’sorder, there is not enough reserve in the 3PL’s warehouse, 3PL should not with-hold the pharmacy’s order, but partially execute the order by shipping the restof the items, while at the same time 3PL should notify the pharmaceutical com-pany for producing the item that is out of stock. Thus, the item that was notavailable remains as an outstanding order that will be fulfilled when the itemwill be available from the pharmaceutical company. (ii) 3PL should fulfil at least5 orders for each pharmacy on a daily basis, and (iii) 3PL should complete thefulfilment of an order within 3 hours. It is evident that the first clause concernsthe functional aspect in terms how 3PL should handle the fulfilment of an order,whereas the other two clauses concern the non-functional aspect in terms of timeconstraints that have to be respected to impose a specific quality level for theoutsourced service.2 Run-time Monitoring of Conformance to BLAsA BLA is a contract between a service provider and a service consumer that de-scribes the agreed functional and non-functional characteristics of a Web service.In order to assure conformance of a service to BLA, it is necessary to performmonitoring during the execution of a Web service for a number of reasons: (i)Towards Run-time Monitoring of Web Services Conformance to BLA 3Dynamic changes/upgrades in implementation may unwittingly break previouscontracts after testing is formally over; (ii) Conditions at run-time may introducenon-determinism (particularly when sharing resources) that requires monitoringand compensation at run-time; (iii) The existence of a conformance monitoringcapability is a kind of guarantee for the consumer that redress is possible if theBLA is not honoured.To support run-time monitoring, a representation of the BLA is requiredwhich allows to express both functional and non-functional characteristics in amachine-readable way. This representation should be abstract enough to hidethe actual implementation of a service, while exposing the steps, rules and de-pendencies that comprise the workflow of a business process, together with thequalitative characteristic of this workflow. Additionally, it should be complemen-tary and separated from existing descriptions for Web services.For addressing the verification of functional characteristics we use the methodpresented in [15], which employs the Stream X-Machines (SXM) formalism [16]for modelling the Web services. The animation of the SXM model is supportedby the JSXM tool [17] and serves as an oracle for the run-time monitoring of theservice. For implementing a prototype of the run-time infrastructure for verifyingthe conformance of Web service to BLA, we use the JBoss application server forthe deployment of Web services. We utilize SOAP message handlers provided inJAX-WS API [18] for intercepting SOAP messages. Handlers are classes that actas pre-processors and post-processors for SOAP messages. A handler forwardsSOAP request/response messages to an external monitoring component. Themonitoring component is a Web service itself, which transforms the forwardedmessages to SXM inputs/outputs, and then it uses them to perform animationof the SXM with the JSXM tool.The run-time conformance monitoring of Web service to BLA has been in-spired by the fragmented work that exists for the run-time monitoring of Webservices. For instance, [1–4] address the run-time monitoring of functional char-acteristics of composed Web services, as well as for individual services [5–8].Additionally, there are existing methodologies for verifying the non-functionalcharacteristics of atomic Web services [9, 10], and approaches concerning com-posed services [11, 12]. Each of the aforementioned works manage to solve a smallfragment of the problem, and it is therefore suggested to combine the existingapproaches, in order to tackle more complex monitoring of Web services [13].3 Future WorkAs future work we plan to devise an abstract and machine-readable represen-tation for BLAs, which will be able to express business agreements that wouldhave to exist between providers, brokers and consumers. Furthermore, while theSXM approach can address the verification of the functional aspect of a BLA, thegreat amount of monitoring methods available inspires us to consider an openarchitecture, which will facilitate the utilization of different monitoring methodsunder a common framework.4 Konstantinos Bratanis, Dimitris Dranidis, and Anthony J.H. SimonsReferences1. Baresi, L., Ghezzi, C., Guinea, S.: Smart monitors for composed services. Proceed-ings of the 2nd international conference on Service oriented computing. pp. 193-202.ACM, New York, NY, USA (2004).2. Lazovik, A., Aiello, M., Papazoglou, M.: Associating assertions with business pro-cesses and monitoring their execution. Proceedings of the 2nd international confer-ence on Service oriented computing. pp. 94-104. ACM, New York, NY, USA (2004).3. Mahbub, K., Spanoudakis, G.: A framework for requirents monitoring of servicebased systems. Proceedings of the 2nd international conference on Service orientedcomputing. pp. 84-93. ACM, New York, NY, USA (2004).4. Kallel, S., Charfi, A., Dinkelaker, T., Mezini, M., Jmaiel, M.: Specifying and Mon-itoring Temporal Properties in Web services Compositions. Proceedings of the 7thIEEE European Conference on Web Services (ECOWS). (2009).5. Li, Z., Jin, Y., Han, J.: A Runtime Monitoring and Validation Framework for WebService Interactions. Proceedings of the Australian Software Engineering Conference.pp.70-79. IEEE Computer Society (2006).6. Gan, Y., Chechik, M., Nejati, S., Bennett, J., O’Farrell, B., Waterhouse, J.: Runtimemonitoring of web service conversations. Proceedings of the 2007 conference of thecenter for advanced studies on Collaborative research. pp. 42-57. ACM, RichmondHill, Ontario, Canada (2007).7. YuYu Yin, Y.L.: Verifying Consistency of Web Services Behavior. Presented at the2008 IEEE Asia-Pacific Services Computing Conference December 9 (2008).8. Simmonds, J., Gan, Y., Chechik, M., Nejati, S., O’Farrell, B., Litani, E., Water-house, J.: Runtime Monitoring of Web Service Conversations. IEEE Transactions onServices Computing. 99, 223-244 (2009).9. Ameller, D., Franch, X.: Service Level Agreement Monitor (SALMon). Proceedingsof the Seventh International Conference on Composition-Based Software Systems(ICCBSS 2008). pp. 224-227. IEEE Computer Society (2008).10. Kotsokalis, C., Yahyapour, R., Rojas Gonzalez, M.: Modeling Service Level Agree-ments with Binary Decision Diagrams. Service-Oriented Computing. pp. 190-204(2009).11. Barbon, F., Traverso, P., Pistore, M., Trainotti, M.: Run-Time Monitoring of In-stances and Classes of Web Service Compositions. Proceedings of the IEEE Interna-tional Conference on Web Services. pp. 63-71. IEEE Computer Society (2006).12. Xiao, H., Chan, B., Zou, Y., Benayon, J.W., O’Farrell, B., Litani, E., Hawkins,J.: A Framework for Verifying SLA Compliance in Composed Services. 2008 IEEEInternational Conference on Web Services. pp. 457-464, Beijing, China (2008).13. Baresi, L., Guinea, S., Pistore, M., Trainotti, M.: Dynamo + Astro: An IntegratedApproach for BPEL Monitoring. Web Services, IEEE International Conference on.pp. 230-237. IEEE Computer Society, Los Alamitos, CA, USA (2009).14. Kreger, H.: Fulfilling the Web services promise. Communications of the ACM. 46,29 (2003).15. Dranidis, D., Ramollari, E., Kourtesis, D.: Run-time Verification of BehaviouralConformance for Conversational Web Services. Proceedings of the 7th IEEE Euro-pean Conference on Web Services (ECOWS). (2009).16. Eilenberg, S.: Automata, Languages, and Machines.Academic Press, Inc. (1974).17. D. Dranidis, JSXM: A Suite of Tools for Model-Based Automated Test Generation:User Manual. Technical Report WP-CS01-09, CITY College, 2009.18. JSR 224: JavaTM API for XML-Based Web Services (JAX-WS) 2.0. Java Com-munity Process, http://jcp.org/en/jsr/detail?id=224 (2009).

Towards run-time monitoring of web services conformance to business-level agreements

Konstantinos Bratanis

Dimitris Dranidis

Anthony J. H. Simons

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Towards Run-Time Monitoring of Web Services Conformance to Business-Level Agreements

Abstract. Web service behaviour is currently specified in a mixture of ways, often using methods that are only partially complete. These range from static functional specifications, based on interfaces in WSDL and preconditions in RIF, to business process simulations using executable state-based models such as BPEL, to detailed quality of service (QoS) agreements laid down in a service level agreement (SLA). This paper recognises that something similar to a SLA is required at the higher business level to govern the contract between service producers, brokers and consumers. We call this a business level agreement (BLA) and within this framework, seek to unify disparate aspects of functional specifica-tion, QoS and run-time compensation. We propose that the method for validating a web service with respect to its advertised BLA should be based on run-time service monitoring. This paper reports progress to-wards defining these goals. Key words: run-time verification, business-level agreements, Web ser

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Abstract. Web service behaviour is currently specified in a mixture of ways, often using methods that are only partially complete. These range from static functional specifications, based on interfaces in WSDL and preconditions in RIF, to business process simulations using executable process-based models such as BPEL, to detailed quality of service (QoS) agreements laid down in a service level agreement (SLA). This paper recognises that something similar to a SLA is required at the higher business level to govern the contract between service producers, brokers and consumers. We call this a business level agreement (BLA) and within this framework, seek to unify disparate aspects of functional specifica-tion, QoS and run-time verification. We propose that the method for validating a web service with respect to its advertised BLA should be based on run-time service monitoring. This paper reports progress to-wards defining these goals

http://staffwww.dcs.shef.ac.uk/people/A.Simons/research/papers/towardsmonitoring.pdf

Towards run-time monitoring of web services conformance to business-level agreements

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