A Framework for Contract-Based Collaborative ... - Semantic Scholar

A Framework for Contract-Based Collaborative Verification and Validation of Web Services Xiaoying Bai Department of Computer Science and Technology Tsinghua University [email protected] 2007.7

Outline  Research motivation and background  The test broker architecture for Decentralized Collaborative Verification and Validation (DCV&V)  DCV&V contracts  Contract-Based test generation  Conclusion 10/7/2007

CBSE'07, July 9-12 2007

2

Motivation  Service-Oriented Architecture (SOA) and its implementation Web Services (WS) are redefining the entire process of software development. 

Software delivery, discovery, composition, collaboration

Organization A

Organization B

Organization C

+

t1 Setup

WS1 WS2 10/7/2007

+

t5 t2

t3

t4

Prepare Sample

Prepare Clones and Sequence

Assembly

WS3

t6

t7

Test Quality Get Sequences Sequence Processing

WS7

WS4 July 9-12 2007 CBSE'07,

WS5

WS9

t8 Process Report

WS8

WS6

3

Motivation  Standard-based dynamic collaboration is a key feature of WS systems.

10/7/2007

CBSE'07, July 9-12 2007

4

Motivation  Trustworthiness is a big challenge for dynamic collaboration. 

The success of WS depends on its capability to resolve the testing issues. (Bloomberg 2002)

"Web services are not yet widely used because of security concerns. But there's an even bigger roadblock waiting just down the road -- it's called trust. The big issue is 'Will the service work correctly every time when I need it?' As yet few are thinking about the issues of testing and certification. We suggest that testing and certification of Web services is not business as usual and that new solutions are needed to provide assurance that services can really be trusted." -- In CBDi Forum, 11 Jul 2002 10/7/2007

CBSE'07, July 9-12 2007

5

Motivation  New challenges for WS testing 

Assessment of a large number of services  Large number of services meeting the same specification could be

available over the open Internet platform 

Dynamic testing and automated testing  The dynamically constructed application has to be tested

dynamically at runtime automatically without human intervention following the specification-based approach. 

Cooperative testing  The distributed architecture requires cooperation and collaboration

among different testing activities and stakeholders including service provider, service consumer, and service brokers. 10/7/2007

CBSE'07, July 9-12 2007

6

WS Collaborative Verification and Validation (CV&V)

WebStrar Infrastructure

Service brokers: Service developers/providers:  To enable the collaboration anddatabase, cooperation Access tools, and composeof newall WS the Submit WS + test cases + test case oracle parties involved in SOA to perform WS testing. Test case Model  WebStrar testing services and WS Testing Infrastructure Master Test for case database generators checking service-based applications WSDL WS Reliability Test case Oracle Test case OWL-S models ranking models generators validation  TheReliability trustworthy service broker DAML-S database



Extend UDDI by adding just-in-time WS testing, Service WSserver ranking models Local or remote composition evaluation, and ranking capabilities. WS directory

Service Requestors/ Clients 10/7/2007

Policy & Standards

Trustworthy WS repository

Composite WS

Validation

Researchers and regulators: Analyze data, monitor quality, and dynamically replace models and tools CBSE'07, July 9-12 2007

7

The Test Broker Architecture for CV&V Test Provider

7

4

Tester 6

1

3

2 8 Test Broker

5

Service Broker

9

10

10/7/2007

Service User

CBSE'07, July 9-12 2007

Service Provider

8

The Test Broker Architecture for CV&V  The test provider can be Service provider  Service requester  Independent tester 

10/7/2007

 The tester can be Service provider  Service requester  Service broker  Certification organization  Independent tester 

CBSE'07, July 9-12 2007

9

The Test Broker Data Structure Test Broker

Service Broker

TestEntity

BusinessEntity

TestCase TestBinding

BusinessService TestModel

ServiceLinking

tModel

BindingTemplate

tModel

BindingTemplate BusinessService

TestCase TestBinding

TestModel

tModel

BindingTemplate

tModel

BindingTemplate

ServiceLinking

10/7/2007

CBSE'07, July 9-12 2007

10

The Test Broker Services Test Broker Test Submission

Test Repository 10/7/2007

Test Case Management

Test Query

Defect Management

Test Generation

Test Profile Management Evaluation Management

Test Collaboration Test Evaluation

CheckInTest CheckOutTest GenerateTest QueryTest RunTest ServiceEvaluation TestEvaluation

Service Evaluation CBSE'07, July 9-12 2007

11

Decentralized Test Brokers  Multiple loosely coupled test brokers distributed in the Internet environment.  Each test broker may be dedicated to different V&V tasks or target domains.  Enable scalable and flexible collaboration among test participants.  A broker can flexibly join or quit the collaboration. Collaborations can be established at runtime through negotiation. 10/7/2007

CBSE'07, July 9-12 2007

12

DCV&V Contracts  TSC: Testing Service Contracts – Collaboration between test and service under test Test designers get service specification for test generation.  Test executors exercise the test on the service interface.  Test evaluators evaluate the service based on test results and defect reports. 

 TCC: Test Collaboration Contracts – Collaboration among test participants 

10/7/2007

Protocols for collaborative test design, execution, and evaluation. CBSE'07, July 9-12 2007

13

Test Collaboration Contract  Test Design  Test Case  Test Scenario

 Test Scheduling  Test Plan  Test Run

 Test Execution

) 5 !"#$ -.)

6

!"#$ '()&*+, )

5

5

6 6 5 5

5 ) )

) )

)

 Test Result

6

 Defect

!"#$ 7/&)

 Test Evaluation

)

!"#$ %&#"

)

) ) !"#$ -"#./$

0"1"($ 6

5

) 6

)

-"/+&2 3+/+$4

 Reliability 10/7/2007

CBSE'07, July 9-12 2007

14

Contract-Based Test Generation  OWL-S specification  OWL-S introduces Ontology into service

representation to improve the mutual comprehension of the operation semantics.  ServiceModel models the service composition as a workflow of processes.  A composite process holds a Control Construct  An atomic process represents a service with IOPE (Input, Output, Precondition, Effect) 10/7/2007

CBSE'07, July 9-12 2007

15

Contract-Based Test Generation  Test Process generation based on Petri-Net model Petri-Net model has a strong capability to model events and states in a distributed system and to capture sequential, concurrency and event-based control.  OWL-S processes are mapped to a Petri-Net model.  Petri-Net provides powerful support for analyzing and verifying certain properties such like reachability, liveness, and deadlocks.  Based on the Petri-Net topology, test processes are generated to cover various execution paths. 

10/7/2007

CBSE'07, July 9-12 2007

16

Contract-Based Test Generation  Constraint-guided test generation  WSDL data constraints based on XML schema  E.g. {length = ”5”, pattern = ”[A − Z]{2}[0 − 9]{3}”}.  OWL-S preconditions

10/7/2007

CBSE'07, July 9-12 2007

17

Contract-Based Test Generation  Process constraints

10/7/2007

CBSE'07, July 9-12 2007

18

The Prototype System Service Spec WSDL

Spec Analysis

Modeling

BPEL Model Checking

OWL-S

Test Agent

Test Generation

Adaptive Strategy Selection

Controller

Result Analysis

测试驱动 Driver

Service & Service Composition 10/7/2007

测试监控 Monitor CBSE'07, July 9-12 2007

19

The Prototype System

10/7/2007

CBSE'07, July 9-12 2007

20

Conclusion  A test broker architecture is proposed and the prototype system is being developed. The test broker enables collaborations among test participants  The test broker collaborates with the service broker to enforce runtime service testing and evaluation  The test brokers are loosely coupled and decentralized to enhance scalability. They can dynamically establish collaboration. 

 The contracts for broker-based test collaboration is analyzed including TCC and TSC.  The contract-based automatic testing is discussed. 10/7/2007

CBSE'07, July 9-12 2007

21