Model-Based Self-Adaptation from Requirements to Architectures: A Decision- Making Process. Bihuan Chen

Transcription

1 Model-Based Self-Adaptation from Requirements to Architectures: A Decision- Making Process Bihuan Chen School of Computer Science, Fudan University, Shanghai, China bhchen@fudan.edu.cn

2 Real-Life Adaptation Scenarios An online shopping company launches a sales promotion Performance degradation Performance degradation Infos Runtime Architecture Switch to parallel Chief Architect Infos Business Manager Runtime Architecture No design solution Skip fraud ing and logging Remove components Chief Architect Chief Architect Credit Adapt Credit Adapt Infos Fraud Fraud Credit

3 Observations Adaptations often involve both requirements and architectural decisions, focusing on different concerns and requiring different knowledge Mappings from requirements to architectural elements often involve complex traceability and the knowledge about design decisions Model-based self-adaptation can be regarded as an automation of these adaptation processes at runtime

4 Adaptation Request (Quality preferences, Context Changes) A Framework of Self-Adaptation Requirements Adaptation Manager Adapted Goal Specification Design Decisions Adaptation Manager Adapted Design Solution Transformation Generator Planner Adaptation Request (Quality Preferences) Model Transformation Scripts Requirements Goal Model Requirements Layer Architecture Layer Design Decisions Model Architecture Transformer Current Model Runtime Architecture Model i Adapted Model Runtime Architecture Model i+1 Analyze Engine Runtime Data Running System Reconfigurations Execution Engine

5 Requirements Layer Adaptations Quality requirements tradeoffs Browsing response (t1) > Usability (t1) Usability (t2) > Browsing response (t2) Solution Tune the preferences of quality requirements using a feedback controller Switch among alternative goal specifications t1 Search product Product be chosen Details be viewed t4 Add to cart X. Peng, B. Chen, Y. Yu, and W. Zhao, Self-tuning of software systems through dynamic quality tradeoff and value-based feedback control loop, JSS, X t2 View in multimedia OR 0.9+ Browsing X response be quick OR 0.8+ X t3 View in text X Usability be good

6 Functional requirements tradeoffs Browsing (t) > Consultation (t) Solution Requirements Layer Adaptations X Make consultation 0.4 Product be chosen Products be sold Order be ed out Annotate a value between 0 and Order be verified Make Review Distinguish between critical goals and desired goals Bind/unbind desired goals B. Chen, X. Peng, Y. Yu, and W. Zhao, Are your sites down? Requirements-driven self-tuning for the survivability of web systems, RE, X

7 Architecture Layer Adaptations Architecture: functionalities + design decisions Hard Goal Goal Soft Goal Task Motivation Link rationale Design Issue problem Design Option solution Impact Link pros and cons Dependency Link dependency Architectural Modification realization pre-condition Context

8 Architecture Layer Adaptations 0.6+ t5 Place order Resources be low Order be ed out Synchro nous t6 Pay order Pay response be quick [requestamount > 80] Asynch ronous Products be sold Simple verification Simple OR Order be verified Cost be low 0.6+ Risk be low OR Order be strictly verified Order be simply verified t7 Check t8 Check info 0.8- credit Payment 0.7+ protocol Order verification Sequential t9 Check fraud Check response be quick Parallel 0.8+ Strict verification Strict

9 Architecture Layer Adaptations Simple architectural adaptations Adding, removing, replacing architectural elements Complex architectural adaptations Crosscutting and restructuring architectural elements Achieve the model adaptations by incremental and generative model transformations Architecture model i -> Architecture model i+1 Automatically generate scripts using template engine

10 Conclusions A model-based self-adaptation approach Combine requirements and architectural adaptations Consider structures and behaviors of architectures by design decision models Support crosscutting and restructuring architectural adaptations using incremental and generative model transformations

11 Thanks for your attention!