A Reference Architecture for

Component-Based

Self-Adaptive Software Systems

Lorena Castañeda Bueno

Advisor: Gabriel Tamura

• Today’s software applications face

unpredictable context changes, including

business goals changes in organizations

• Software systems must fulfill these

changes in requirements in a very short

time, and especially at runtime.

• Software adaptation is expensive and

takes a lot of time and effort.

2

Motivation

Lets see an example…

Motivation

Mobile Banking Service

�Manage Accounts

�Payments

�Transfers

new

Secure and Fast

Too much time!

�Security protocols

�Cryptography

3

THIS REQUIRES SYSTEMS THAT CAN BE MORE

SELF-MANAGEABLE

• Software engineering for Self-Adaptive Systems

community have made significant efforts to propose

self-adaptive systems, however:

– Not general enough to fit the different systems to build

self-adaptive software

– Adaptation mechanisms merged with the target system.

– Feedback loops are not explicit in most of these

proposals.

Motivation

4

1. Background

2. The Problem

3. Solution and Contributions

4. Evaluation

5. Conclusions and Future Work

5

Presentation outline

Knowledge Areas:

1. Autonomic Computing and Software Adaptation

2. Self-adaptive Software System Approaches

3. Component-Based Software Engineering

4. Software Architecture, Reference Models and

Reference Architectures

6

Background

1. Autonomic Computing and Software

Adaptation

• Self-managed systems:

– The capability to run routine tasks and maintenance

without the intervention of the system administrator.

• Adaptation refers to the capability of changing the

software structure and behavior to meet the

changing business requirements.

• Feedback is the process to return an output of the

system to check if the control objectives are being

achieved

7

Control loop

• Control loop is the feedback

mechanism to control the dynamic

behavior of the system, supported in

four activities:

– Collect – Relevant data from

the system and environment

– Analyze – the collected data

– Decide – how to adapt in

order to reach a desirable

state

– Act – realize in the system the

decisions made by the control

8“Software engineering for self-adaptive systems: A research roadmap” B. H. Cheng et al.

2. Self-adaptive software system

approaches

1. IBM’s autonomic computing - ACRA

2. Kramer and Magee, three layer reference

architecture

3. Garlan, the Rainbow Framework based on

reusable architecture and external adaptation

4. Parra’s Cappucino architecture

5. Solomon’s autonomic system

6. DYNAMICO reference model

9

Autonomic computing reference

architecture (ACRA) - IBM

10

Level 1

Level 2

Level 3

Level 4

Level 5

An Architectural blueprint for autonomic computing, IBM, 2005

LEVEL 3 - Autonomic manager

• It is the component that

implements the control loop:

1. Monitor

2. Analyzer

3. Planner

4. Executer

5. These four elements

communicate to and

collaborate with each other

and exchange appropriate

Knowledge and information.

11

LEVEL 2 – Touchpoints

• Components that expose the state and management

operations for a managed resource

12

Managed Resources

Data sources Other systems

To effect

changes

(operations)

To sense

changes

(properties

and events)

Target System

DYNAMICO: A Reference Model for Governing Control

Objectives and Context Relevance in Self-Adaptive

Software Systems

13

Control

objectives

Adaptation

Control

Context

control

Villegas, N.M., Tamura, G., Müller, H.A., Duchien, L., Casallas, R, LNCS Vol.7475, 2012

3. Component-Based software engineering

� Software elements Independently

developed and deployed

� Hides all the complexity of the

software implementation

� Components reuse

� Permits easy replacement

14Component-based software engineering, George Heineman and William

Councill, 2007

SOFTWARE

COMPONENT

• An architecture in software defines the elements that

compose the system and the relationship between those

elements.

15

4. Software Architecture, Reference

Models and Reference Architectures

Software Architecture In Practice, Len Bass and Paul Clements and Rick Kazman, 2003

Decomposition of

a well known type

of problem

A set of elements in

component types and the

relationships among them

Mapping between a Reference

Model, Architectural Patterns and

the data flow among them

2. THE PROBLEM

16

Changing context and software adaptation

The Problem

Different systems, data types

configurations

Self-Adaptation merged

with the Target System

Feedback loops are

not explicit

To build self-adaptive systems

with heterogeneous available

systems

The necessity to

manage adaptation

mechanism

Measure the output

of the system and

evaluate adaptation

17

3. PROPOSED SOLUTION

18

Our Reference Architecture

PROJECT GOALS:

1. To design and implement a component-

based reference architecture for

component-based self-adaptive software

systems.

– Separation of concerns

– Distribution

– Extensibility

2. To evaluate our proposal In an specific

case of study

19

20

1. Pipes and Filters

2. Event-Based

3. Blackboard

An Introduction to software architecture, David Garlan and Mary Shaw, 1994

1. Control Feedback loop

2. DYNAMICO

+

++ Data Flow

Our high level goal is to

provide software engineers

with a guide to design

software architectures for

self-adaptive systems

21

Architecture Data Flow

Target SystemAdaptation

mechanism

THE INFORMATION IS

CONTEXT RELATED

Architecture Data Flow

CONTEXT METAMODEL

by Villegas et al.

Our reference

architecture context

metamodel

22

Context-Driven Adaptive Monitoring for Supporting SOA Governance, Villegas and Müller, 2010

Architecture Data Flow

CONTEXT METAMODEL subset

23Context-Driven Adaptive Monitoring for Supporting SOA Governance,

Villegas and Müller, 2010

Diagnosis

Context Data

Context Event

information

Adaptation

Actions

Commands

24

Our Architecture Data Flow Proposal

Architecture Data Flow

25

Registration

request

(Tx/min)

In the last minute

115 (Tx/min)

Current Tx/min is 115.

Desired Tx/min for today is 100

115 > 100 -> Adaptation is required

A SLO describes that for a given day, the Maximum

of Transactions per minute allowed is 100, if more

then adaptation is required

26

+

++ Data Flow

27

Our Reference Architecture for Component-Based

Self-Adaptive Software Systems Implementation

� Adaptation Mechanism

� Human Interaction

� Context Interaction

27

28

Registration

request

115 Registration

request in the last

minute

Monitoring

policies

Analyzing

Policies

SLO: Max 100

Current : 115

Desired: 100

Adaptation

Planning

policiesAdaptation

Actions

Commands

Our Reference Architecture for Component-Based

Self-Adaptive Software Systems Implementation

General Representation

29

An Interface to

expose services

An Abstract class to

define basic

behavior

A Specific

implementation

Java Implementation

3030

4. EVALUATION

31

Evaluate a concrete architecture derived from our Reference Architecture

�A Case of Study

� Explore its extensibility to support dynamic adaptation of SCA Software Applications

� Explore its distribution executing the components separately

Evaluation

32

Reliable Videoconference Service (RVCS)

33

Vid

eo

-Co

nfe

ren

ce S

yste

m

Vid

eo

-co

nfe

ren

ce c

lie

nt

Establishment of Service

Conditions (QoS)

Registers and Attends

A concrete SCA Architecture derivation

from our Reference Architectura

34

Service Component Architecture, Assembly Model Specification. Specification Version

1.0, Beisiegel, M. and Blohm, H. and Booz, D. and Edwards, M. and Hurley, O., 2007

Each component is

described in its

own composite

One composite file to

group all components

35

Testing Deployment Configuration

Not implemented

Test Cases and Results

36

Test Results

37

Amount of

Requests

Evaluation

criteriaSLO

Fulfillment

Adaptation

Requirement

Test 2 Results

38

Test 2 Results

39

Test 3 Results

40

�A Case of Study

� Extensibility: SCA Software Applications

�Distribution: Separating MAPE-K from Sensor and Effector

Evaluation Results

41

5. CONCLUSIONS AND FUTURE

WORK

42

Conclusions (I)

Our reference architecture provides a generic

framework to implement adaptation mechanisms for

software systems.

• Separation of concerns enabling the evaluation,

maintenance and analysis of the adaptation process in a self-

adaptive system.

• Data flow modeling using an extensive context metamodel

43

Conclusions (II)

Based on components, this reference architecture also

provides

– component reuse,

– the ability to be extensible and interoperable,

which can help software engineers to specialize,

extend and grow the functionalities of each

component, according to the necessities of the specific

target system.

44

Conclusions (III)

As an SCA-compliant implementation, our reference

architecture fulfills the goal of being extensible

Each SCA component of the reference architecture is

defined in its own composite file in order to fulfill

the distribution capability

45

Future Work

• Security between the Target System and the MAPE-K

• AMC development to assist humans in the definition

of SLOs.

• Include V&V modeling in the Reference Architecture

• V&V after adaptation

• Planner and Executer extensions

46

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