*An Integrated Self-Testing Framework for Autonomic Computing Systems

Tariq M. King, Alain E. Ramirez, Rodolfo Cruz, Peter J. Clarke

School of Computing and Information Sciences

Florida International University

07/14/2007

FIU-SCIS Departmental Colloquium

* To appear in Issue 8 2007 of the Journal of Computers * Supported in part by the National Science Foundation under grants IIS-0552555 and HRD-0317692

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Introduction o Continual growth in size and complexity of

computing systems has led to a need for support tasks to be shifted from people to technology

o Movement towards self-managing systems that can dynamically configure, heal, protect, and optimize themselves – Autonomic Computing.

o There is a lack of techniques to dynamically validate such systems.

o How can we be sure that AC systems behave correctly after a change at runtime?

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Introduction (cont’d)o This work presents a methodology which

dynamically validates changes resulting from self-management in autonomic systems.

o Applies the concepts of autonomic managers, knowledge sources and manual management facilities to testing activities.

o Provides two general strategies based on system constraints and feasibility of use.

o Elaborates on a prototype that uses a generic design for autonomic systems that supports runtime testing.

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Outlineo Background

o Overview of Testing Approach

o Test Managers

o Test Support Components

o Challenges

o Prototype

o Related Work

o Conclusion & Future Work

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Autonomic Computing (1)o IBM’s solution to the problems of integrating and

managing highly complex computing systems

oHuman Body – ANS regulates vital bodily functions without conscious human involvement (homeostasis)

o Applied to Computing Systems – automation of low-level tasks, and high-level goal specification.

oMain CharacteristicsSelf-Configuration: configuring existing / new components

Self-Optimization: balancing workloads, tuning efficiency

Self-Protection: safeguarding from attacks or failures

Self-Healing: diagnosing and repairing problems

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Autonomic Computing (2)

Layered Architecture of Autonomic ComputingSource: An Architectural Blueprint for Autonomic Computing, Fourth Ed., IBM Corporation, June 2006.

o Management console to facilitate human activity

o Coordinates Touchpoint AMs (within or across)

o Manages resources directly through touchpoint layer

o Implements sensor and effector interface for MR

o H/W or S/W entities being managed

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Autonomic Computing (3)o Monitor: collects state

information from MR

o Analyze: determines if and when self-* is needed

o Plan: formulates a plan to address change request

o Execute: executes the change plan on the MR

o Knowledge: stores data shared by the MAPE functions

MAPE Structure of Autonomic ManagersSource: An Architectural Blueprint for Autonomic Computing, Fourth Ed., IBM Corporation, June 2006.

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Software Testing - Categorieso Two broad types of testing:

o Blackbox – specification-based, focuses on functionality, i.e., inputs → expected outputs.

o Whitebox – implementation-based, focuses on whether or not the program has been thoroughly (adequately) exercised.

o Regression Testing – determines whether or not modifications to software have introduced new errors into previously tested code.o Retest-all – retest the entire test suite

o Selective – only retest a strict subset

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Software Testing - Automationo Automating the testing process involves:

1) Designing test cases

2) Developing test scripts

3) Setting up a test harness for automatically: Setting up the test environment

Executing test cases

Logging the test results

Evaluating the test log

o What happens when the post-test evaluation passes or fails?

o Whitebox – implementation-based, focuses on whether or not the program has been thoroughly (adequately) exercised.

o Regression Testing – determines whether or not modifications to software have introduced new errors into previously tested code.o Retest-all – retest the entire test suite

o Selective – only retest a strict subset

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Safe AdaptationZhang et al. (WADS 2004)

Source: J. Zhang, B. H. C. Cheng, Z. Yang, and P. K. McKinley. Enabling safe dynamic component-based software adaptation. In WADS, pages 194–211, 2004.

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Testing Approach – Overviewo Idea: Develop an implicit self-test characteristic

for autonomic computing systems

o Integrate activities of a self-testing framework into the workflow autonomic managers (AMs)

o Test Managers interface with the autonomic system and coordinate the testing activity

o Framework consistent with grand vision of AC

o Based on two strategies: Safe Adaptation with Validation

Replication with Validation

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Testing Approach - Architecture

Integrated Self-Testing Framework for AC Systems Extends the dynamic test model by King et. al, “Towards Self-Testing in Autonomic Computing Systems”Based on two general approaches: Safe Adaptation with Validation, and Replication with Validation

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Test Managers (TMs)o Extend the concept of autonomic managers to

testing activities, i.e., Self-Testing via MAPE

o Responsible for:Test Coordination

Test Planning and Execution

Test Suite Management

Pre- and Post-test Setup

Post-test Evaluation

Storage of Test Artifacts

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High-Level Test Coordination1a,1b) Monitors OAM & TKS for state changes

2) Uploads new validation policy to Touchpoint TM

3) Touchpoint TM needs support tools to be setup

4) Invokes effector of ATS to configure support tool

5) Support tool configured successfully for TTM

6) TTM notified that it can begin test execution

Orchestrating TM Interactions Manages multiple components in the self-testing framework for high-level test coordination

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Low-Level Testing Tasks

Touchpoint TM Interactions Performs testing on managed resources of the autonomic system via two control loops (a) and (b)

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Test Support Componentso Auxiliary Test Services (ATS) allows TMs to

configure external or third-party testing tools, code profilers, performance analyzers, etc.

o Provides mechanisms for accessing information in the test knowledge sources. updating validation policies, test suites, test logs/histories

o Implements facilities for administrative functions related to manual test management, interactive test management, defect tracking, scenarios

o Administrative functions will be integrated with the console of the autonomic system

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Challengeso V&V techniques for offline systems not scalable;

and still heavily dependent on human tester.

o Drawbacks magnified for adaptive systems.

o Testing adaptive nature requires dynamic:Regression test case selection

Test suite analysis to:– generate new test cases when necessary.– identify test cases that are no longer applicable.

o Testing autonomic systems in the presence of unforeseen conditions

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Overcoming Challengeso Using proposed framework as the focal point for

research directions to support QA in AC systems

o Some Directions:Use of formal specifications to generate test

sequences, test oracles, and test data

Executable formal specifications also support visualization systems (grand challenge of AC)

Mechanisms for policy-based risk analysis and trust can support testing in unforeseen circumstances

Risk-based strategies for regression test case selection

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Prototype - Featureso Autonomic Container – Data structure with

autonomic capabilities and implicit self-testo Version 1 – Stack with self-configuration and self-

test. 80% full, reconfigure by increasing capacity

o Version 2 – Implemented as a remote stack and added self-protection. Users stack exceptions > 3, protect by disabling user

o Implemented Replication with Validation Validation required 100% pass rate for test cases,

75% for both branch and statement coverage Test suite: 24 test cases, using boundary,

random, and equivalence partitioning.

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Prototype – Setup Environmento Developed in Java 5.0 using Eclipse 3.3 SDK

with required test support plugins and libraries.o Design Tools:

StarUML – class, activity, package diagrams

OribeXML – creating and modifying XML policies

o Test Support Tools:JUnit – a Java unit testing tool from the xUnit family

of testing frameworks

Cobertura – a Java code coverage analysis tool that calculates the percentage of source code exercised by unit tests.

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Prototype – Top-Level Design

Top-Level Design of Autonomic Container

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Prototype – Manager Design

Generic Design of Autonomic Managers

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Prototype – Policy Design

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Prototype – Self-Test Classes

Minimal Class Diagram of Self-Test Subsystem

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Prototype – Evaluationo Used a mutation testing technique to evaluate

the fault detecting ability of the prototypeo Strategy: simulate faulty change requests to the

managed resource (stack) under SC and SP:SC – created mutant stack by modifying the

resize method to cause decreased capacitySP – created mutant stack by altering disable

account method to enable the usero Analyzed the results of executing the self-testing

framework on original stack and the mutants

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Prototype – Resultso Correct change scenarios:

o Incorrect change scenarios:Two TC failures each, coverage omitted

o Mutation analysis produced favorable results as testing would have prevented potentially harmful changes to the managed resource

Feature TC Pass Rate Branch Statement

Self-Config 100% 85% 100%

Self-Protect 100% 88% 100%

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Prototype – Lessons Learnedo Provided us with insight on the scope of the self-

testing subsystem w.r.t responsibilities.o Synchronization of AMs and intelligent control

loops are a major challenge.o Limitations:

Dynamic test planning (current: static lookup)

Need to implement Safe Adaptation with Validation Strategy

Code-based changes

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Related Worko Towards Self-Testing in Autonomic

Computing Systems, King et al., ISADS ‘07.

o A Self-Testing Autonomic Container, Stevens et al., ACMSE ‘07.

o Synthesizing assertions from observed behavior, Denaro et al., ACC ’05. Embeds assertions into the communication

infrastructure.Assertions are checked at runtime.

o Making components self-testable, Le Troan et al., TOOLS ’99.

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Conclusion and Future Worko Proposed a framework that dynamically

validate change requests in AC systems.

o Approach extends the current structure of AC systems to include self-testing.

o Supports two validation strategies.

o Developed a prototype to show their feasibility.

o Future work calls for: Extending the capabilities of the prototype Implementing safe adaptation with validation Evaluating efficiency of the two approaches

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Summer ’07 and Ongoing Worko REU Program 2007 – Alain E. Ramirez and

Barbara Morales; Autonomic Job Schedulero A Generic O-O Design to Support Self-Testable

Autonomic Systems (SAC ‘07)

o Student Paper to ACMSE 2008

o Fall 2007 – Gonzalo Argote-Garciao Embedding Formal Specifications into Autonomic

Components

o ? – Alain E. Ramirezo Applying Design Patterns to AC systems

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Acknowledgements

Djuradj Babich

Jonatan Alava

Ronald Stevens

Brittany Parsons

Mitul Patel

Dr. S.M. Sadjadi

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Thank You

Questions?

This work has been supported in part by the National Science Foundation under grant IIS-0552555