1 / 35

Leveraging Semantic Web Service Descriptions for Validation by Automated Functional Testing

Leveraging Semantic Web Service Descriptions for Validation by Automated Functional Testing. Ervin Ramollari 1 , Dimitrios Kourtesis 1 , Dimitris Dranidis 2 , and Anthony Simons 3 1 SEERC – South East European Research Centre 2 Computer Science Department – CITY College

fadhila
Télécharger la présentation

Leveraging Semantic Web Service Descriptions for Validation by Automated Functional Testing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Leveraging Semantic Web Service Descriptions for Validation by Automated Functional Testing Ervin Ramollari1, Dimitrios Kourtesis1, Dimitris Dranidis2, and Anthony Simons3 1 SEERC – South East European Research Centre 2 Computer Science Department – CITY College 3 Department of Computer Science – University of Sheffield SEERC - Research Centre of the University of Sheffield and CITY College 1

  2. Presentation outline • Background and motivation • The starting point: semantic descriptions of Web service behaviour • The destination: Stream X-Machine model of Web service behaviour • The derivation method: from IOPE descriptions to an SXM model • Test case generation and execution • Summary and future work SEERC - Research Centre of the University of Sheffield and CITY College 2

  3. Background and motivation SEERC - Research Centre of the University of Sheffield and CITY College 3

  4. Testing and validation of Web services • A service-oriented environment can be open • Integration of third-party Web services • Dependability is a major challenge • Service validation is crucial for engineering dependable service-based systems • Web service implementation should conform to given functional/behavioural specifications • Validation done through functional testing • Manual Web service testing is highly laborious • Definition of test cases, execution and evaluation SEERC - Research Centre of the University of Sheffield and CITY College 4

  5. Leveraging SWS descriptions for automating testing • Semantic Web Service descriptions are utilised for automating a range of activities • Service discovery, composition, mediation… • Less attention has been paid to using them for service testing and validation • Information in SWS descriptions could be exploited for automating test case generation and execution • This information should be represented in a formalism amenable to processing by existing algorithms and tools for test case generation and execution SEERC - Research Centre of the University of Sheffield and CITY College 5

  6. Our background work • Functional testing of Web services • Automated generation and execution of test cases (with completeness guarantees) • Stream X-Machine (SXM) formalism • Used for modelling the behaviour of stateful and conversational Web services • Associated with proven testing method revealing all inconsistencies between implementation and model • Tool support • SXM modelling, model animation, test case generation, test case execution on WS SEERC - Research Centre of the University of Sheffield and CITY College 6

  7. Aim of this work • Could we derive a SXM model from a Semantic Web Service description for the purposes of automated testing and validation? • The derivation approach should be: • Automatable to the greatest extent possible • Independent of any particular SWS framework • Using Semantic Web technology standards SEERC - Research Centre of the University of Sheffield and CITY College 7

  8. The starting point:semantic descriptions of Web service behaviour SEERC - Research Centre of the University of Sheffield and CITY College 8

  9. Semantic descriptions of Web service behaviour • SWS frameworks like OWL-S, WSMO (and ad-hoc SA-WSDL combinations) are heterogeneous • A commonality is describing service operations in terms of inputs, outputs, preconditions, and effects (IOPE) • Transformation of inputs to outputs • Conditional effects on the internal state • All SWS frameworks support IOPE in some form • OWL-S: Inputs, Outputs, Preconditions, Results • WSMO: Preconditions, Postconditions, Assumptions, Effects • SAWSDL: ModelReference annotations on operations SEERC - Research Centre of the University of Sheffield and CITY College 9

  10. IOPE-based descriptions • IOPE is useful for describing stateful and conversational Web services • E.g. shopping cart, e-banking, order management… • IOPE representation requires a combination of • Production rules for expressing: • Conditions for execution (preconditions) • Actions of execution (effects in terms of assertions and retractions) • Ontology for expressing: • Structure of inputs and outputs • Internal state-related variables (i.e. not visible in WSDL) SEERC - Research Centre of the University of Sheffield and CITY College 10

  11. IOPE-based descriptions with RIF-PRD + OWL • In this paper we adopt RIF-PRD and OWL as a possible combination • Why RIF-PRD? • RIF as rule language for the Semantic Web • Production Rule Dialect has operational semantics (specified as an LTS) • RIF-PRD forthcoming W3C recommendation • Why OWL? • W3C recommendation SEERC - Research Centre of the University of Sheffield and CITY College 11

  12. The destination:Stream X-machine model of Web service behaviour SEERC - Research Centre of the University of Sheffield and CITY College 12

  13. Stream X-machines • Stream X-Machines, specialisation of the X-machine model (Eilenberg 1974) • 8-tuple (Σ, Γ, Q, M, Φ, F, q0, m0) • Extend Finite State Machines (FSM) with: • Memory • Processing functions labelling transitions • Complete functional testing method • Proven to reveal all faults in an implementation given that certain design for test conditions are satisfied SEERC - Research Centre of the University of Sheffield and CITY College 13

  14. Bank account service example • Service operations • open • deposit • withdraw • getBalance • close • Operations are invoked according to a protocol (choreography) SEERC - Research Centre of the University of Sheffield and CITY College 14

  15. Bank account service SXM Model SEERC - Research Centre of the University of Sheffield and CITY College 15

  16. SXM processing functions for operation withdraw <function name="withdraw" input="withdraw" output="withdrawOut">   <precondition>withdraw.amount > 0 && balance > withdraw.amount</precondition>   <effect>balance = balance - withdraw.amount; withdrawOut.amount = withdraw.amount;</effect>   </function> <function name="withdrawAll" input="withdraw" output="withdrawOut">   <precondition>withdraw.amount > 0 && balance == withdraw.amount</precondition>   <effect>balance = balance - withdraw.amount; withdrawOut.amount = withdraw.amount;</effect>   </function> SEERC - Research Centre of the University of Sheffield and CITY College 16

  17. The derivation method:from IOPE descriptions to an SXM model SEERC - Research Centre of the University of Sheffield and CITY College 17

  18. Identifying state variables (* wsdl:operation withdraw *) Forall ?account ?status ?balance ?request ?withdrawAmount ( And ( ?account#Account ?account[hasStatus->?status] ?account[hasBalance->?balance] ?request#WithdrawRequest ?request[hasAmount->?withdrawAmount] ) If And (External (pred:string-equal(?status "ACTIVE") External (pred:numeric-greater-than-or-equal(?balance ?withdrawAmount) ) Then Do(Retract (?account[hasBalance->?balance]) Assert(?account[hasBalance->External(func:numeric-subtract(?balance?withdrawAmount))]) Retract (?request) (?response New(?response#WithdrawResponse)) (?newBalance ?account[hasBalance->?newBalance]) Assert (?response[hasAmount->?newBalance) ) ) • Two state variables: • hasBalance • hasStatus SEERC - Research Centre of the University of Sheffield and CITY College 18

  19. Partition analysis • The domains of state variables are determined by consulting their respective ranges in the OWL ontology. <owl:DatatypeProperty rdf:about="#hasBalance"> <rdf:type rdf:resource="&owl;FunctionalProperty"/> <rdfs:domain rdf:resource="#Account"/> <rdfs:range rdf:resource="&xsd;nonNegativeInteger"/> </owl:DatatypeProperty> • hasBalance :== 0…∞ • hasStatus :== {INITIAL, ACTIVE, CLOSED} SEERC - Research Centre of the University of Sheffield and CITY College 19

  20. Partition analysis • State :== hasStatus x hasBalance • E.g. (INITIAL, 0), (INITIAL, 1), …, (ACTIVE, 0), (ACTIVE, 1), … • Examine the preconditions to partition ranges of state variables If And(External (pred:string-equal(?status "ACTIVE") External (pred:numeric-greater-than-or-equal(?balance?withdrawAmount) ) • hasStatus: • ?status = INITIAL • ?status = ACTIVE • hasBalance: • ?balance = 0 • ?balance ≥ ?withdrawAmount AND ?withdrawAmount > 0 • Result • hasStatus: {INITIAL}, {ACTIVE}, {CLOSED} • hasBalance: {0}, {x | x>0} SEERC - Research Centre of the University of Sheffield and CITY College 20

  21. Identifying preliminary states • The preliminary state space is defined as the product of the state variable partitions. • Six states SEERC - Research Centre of the University of Sheffield and CITY College 21

  22. Determining transition pre-states • An input is accepted at a state (pre-state) iff the preconditions are satisfied at the pre-state • E.g. the preconditions of the withdraw operation triggered WithdrawRequest are (hasStatus=ACTIVE and hasBalance>0) . SEERC - Research Centre of the University of Sheffield and CITY College 22

  23. Merging states • Preliminary states in which the same set of inputs is accepted are merged • Cannot be distinguished SEERC - Research Centre of the University of Sheffield and CITY College 23

  24. Determining transition post-states • Apply the effects of the invoked operation on the pre-state to determine the possible post-states. • WithdrawRequest leads to two possible post-states • Two different transitions labelled by different processing functions • Isolated states are removed. SEERC - Research Centre of the University of Sheffield and CITY College 24

  25. Determining guard conditions for processing functions • The guard conditions are the same as the corresponding rule preconditions • Any predicates already satisfied in the pre-state are omitted. SEERC - Research Centre of the University of Sheffield and CITY College 25

  26. Determining memory updates for processing functions • The memory updates of each processing function consist only of the effects which update the memory (M) variables. SEERC - Research Centre of the University of Sheffield and CITY College 26

  27. Test case generation and execution SEERC - Research Centre of the University of Sheffield and CITY College 27

  28. Generation of test cases • SXM test generation based on Chow’s W-method for FSMs • X = S(Φk+1U Φk U… U Φ U{ϵ})W, where • Φ is the set of processing functions (type of the machine) • W is the characterisation set • S is the state cover • k is an estimate of maximum path length between redundant states in the implementation • Supported by tools SEERC - Research Centre of the University of Sheffield and CITY College 28

  29. From abstract to concrete test cases • The generated test cases are at the same level of abstraction as the specification and cannot be executed directly • Abstract test cases are transformed to JUnit test cases • Generation of Java clients with libraries such as WSDL2Java SEERC - Research Centre of the University of Sheffield and CITY College 29

  30. Execution of Test Cases SEERC - Research Centre of the University of Sheffield and CITY College 30

  31. Summary and future work SEERC - Research Centre of the University of Sheffield and CITY College 31

  32. Summary of the approach • Leveraging SWS descriptions for the added-value of testing and validation of services • Strengths of the approach: • SWS framework-independent • Testing supported by existing tools • Uses proven SXM functional testing method SEERC - Research Centre of the University of Sheffield and CITY College 32

  33. Related work • Sinha and Paradkar 2006 • OWL and SWRL rules to describe IOPE • Single-state EFSM • No prescribed test generation method • Keum et al. 2006 • Derive multi-state EFSM from plain WSDL + user-supplied information • Only derivation of states is described SEERC - Research Centre of the University of Sheffield and CITY College 33

  34. Future work • Investigate the decidability of the algorithm and the automation of all steps • Implement tools supporting the transformation • Prove equivalence relationship among original specification and derived SXM model • Utilise SWS grounding information to automate the transformation of abstract test cases to concrete (SA-WSDL annotations pointing to RIF-PRD and OWL) SEERC - Research Centre of the University of Sheffield and CITY College 34

  35. Thank you for your attention! SEERC - Research Centre of the University of Sheffield and CITY College 35

More Related