Generating test cases specifications for BPEL compositions of web services using SPIN José García-Fanjul, Javier Tuya, and Claudio de la Riva Pointner

AK Softwaretechnologie 1 WS 2013/14 1

Generating test cases specifications for BPEL

compositions of web services using SPIN

José García-Fanjul, Javier Tuya, and Claudio de la Riva

Pointner Stefan13.01.2014

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Contents

• Introduction• Specification of web services compositions with BPEL• Overview of the generation of test cases specifications• Transforming BPEL specifications into PROMELA• Using SPIN to generate test case specifications• Conclusion

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Introduction

• Web as a Commercial Channel• Certain exchange protocol XML• Software with XML as Input and Output • XML based Web Services• Distributed• Asynchronous• Platform independent• Low coupled

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Introduction

• Compositions of Web Services• Business Process Execution Language (BPEL)

• Testing Web Services• Asynchronous behavior• Distribution• Availability• Lack of user Interface

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Specification of WS with BPEL

• XML-Documents• Declarations• Specifications

• Declarations• Partners• Variables

• Specification• Basic Activities (Assign, Invoke, Receive)• Structured Activities (Sequence, Flow, While)

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BPEL Example

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<process name="loanapproval" [...]><variables>

<variable name="riskAssessment"

messageType="asns:riskAssessmentMessage"/>[...]

</variables><partners>

<partner name="customer" [...]/><partner name="assessor" [...]/><partner name="approver" [...]/>

</partners><flow>

<links><link name="receive-to-assess"/><link name="assess-to-setMessage"/> [...]

</links><receive name="receive1" partner="customer" [...]>

[...]</receive>

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<invoke name="invokeAssessor" partner="assessor"portType="asns:riskAssessmentPT"operation="check"inputVariable="request"outputVariable="riskAssessment">

<target linkName="receive-to-assess"/><source linkName="assess-to-setMessage"transitionCondition="bpws:getVariableData(’riskAssessment’,’risk’)=’low’"/><source linkName="assess-to-approval"transitionCondition="bpws:getVariableData(’riskAssessment’,’risk’)!=’low’"/>

</invoke> [...]</flow>

</process>

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Business Process

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Test case specification generation

• Simple Promela Interpreter – SPIN• LTL Formulae used for Property-specification• How it works?

• SPIN searches all possible states within the model• Checks whether the properties hold• If not gives a Counter Example

• Generate Test Cases with SPIN• Transform Counter Example to Test Cases

• Process/Protocol Meta Language – PROMELA• Describes models of distributed Systems

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1. Composition Under Test (CUT) is transformed into PROMELA2. Transitions are identified3. Mapping Transitions onto the Model4. Transition expressed as LTL Property5. Run SPIN with the Model and the Input LTL-Properties6. Generate Test Cases with the produced Counter Example

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Transforming BPEL specifications into PROMELA• PROMELA also includes BPEL-partners• BPEL portTypes transformed to PROMELA message channels• chan loanassessor_riskPort_IN = [QLENGTH] of {byte, byte, byte};• Input and Output channel• Message Types are declared as typedefs

• Invoke Activity = !• Receive Activity = ?

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Transforming BPEL specifications into PROMELA - ExampleBPEL_loanApprovalPort_OUT! approvalInfo.accept

• Sends a message containing the variable approvalInfo.accept• to channel BPEL_loanApprovalPort_OUT

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Transforming BPEL specifications into PROMELA – Web Service• If the BPEL specification has no reference to the data, it will be given

an undefined value

• If the data is compared to a numerical constant, it will be given the value of the constant, a lower value and a higher third value

• If the data is discrete, it will be given each of the discrete constants in the BPEL specification and a value different from them, called other

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Transforming BPEL specifications into PROMELA – Transitions BPEL is modelled in PROMELA• transitions are identified in the specification and are mapped within

the model• Implicit Transitions• Invoke• Flow• While

• Explicit Transitions• Are identified from link constructs• Explicitly transitions between activities (with same source or target)

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• Transition expressed as LTL Property• Unique Boolean variables tran1, tran2, tran3, …• Variable will get true in case of the transition being exercised by the model

checker• The variable associated with a transition X is always false [] !tranX• Test Case stop if the property tranX is false• To get to end, change property to:

• [] ( !tranX || !bpel_ends)

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Using SPIN to generate test case specifications



• LTL property: [] ( !tran1 || !bpel_ends)• Example CounterExample for Transition 1, 3, 5:

customer: request.amount = 3customer: BPEL_loanApprovalPort_IN!requestbpel: request.amount<4bpel: tran1 = truebpel: loanassessor_riskAssessmentPort_IN!requestassessor: riskAssessment.risk = lowassessor: loanassessor_riskAssessmentPort_OUT! riskAssessmentbpel: tran3 = truebpel: approvalInfo.accept = yesbpel: tran5 = truebpel: BPEL_loanApprovalPort_OUT!approvalInfobpel: bpel_ends = true

• Transformed into TestCase:• Input: Customer requests for an amount of 3 (less than four)• Input: Assessor sets risk to low• Output: reply to Customer is affirmative

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Full transition coverage with three executions:• {1, 3, 5}• {1, 4, 6}• {2, 6}


Conclusion

• Generate test case specification from BPEL composition of web services• Method relies on SPIN Model Checker• Repeat execute to get a test suite for transition coverage

• Independence from the particular implementation, only BPEL specification as input needed

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Any Questions?

José García-Fanjul, Javier Tuya, and Claudio de la Riva. Generating test cases specifications for BPEL compositions of web services using SPIN. In Antonia Bertolino and Andrea Polini, editors, in Proceedings of International Workshop on Web Services Modeling and Testing (WS-MaTe2006), pages 83-94, Palermo, Sicily, ITALY, June 9th 2006.

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