Winter Term 2011/12 Prof. Dr. Dr. h. c. Dieter Rombach ......Winter Term 2011/12 Prof. Dr. Dr. h. c. Dieter Rombach Chapter 5.4: Software System Engineering - Software Product Line

Software Engineering Research Group: Processes and MeasurementFachbereich InformatikTU Kaiserslautern

Last update: 10/01/2012

Grundlagen des Software EngineeringFundamentals of Software Engineering

Winter Term 2011/12

Prof. Dr. Dr. h. c. Dieter Rombach

Chapter 5.4: Software System Engineering -Software Product Line Architecture

� SW Product Line Engineering (SPLE)�Motivation

�Defintion

�Life cycle

�Goals

� SPL Architecture� Introduction

�Usage

�Process

� Variation Modeling�Modeling in UML

�Feature Model

�Decision Model

� Kobra� Introduction

�Comp. Specification

�Comp. Realization

© Prof. Dr. Dr. h. c. Dieter Rombach, Fundamentals of Software Engineering, Winter Term 2011/12 1

SW Product Line Architecture Goals

� The goals of this chapter are to be able to:

– Define product line engineering

– Understand the concept of commonalities and variabilities

– Understand SPL architectural concepts

– Understand variation modeling

– Characterize Kobra development approach

� Literature

– C. Atkinson, J. Bayer, C. Bunse, O. Laitenberger, R. Laqua, E. Kamsties, D. Muthig, B. Paech, J. Wüst, and J. Zettel. Component-based Product Line Engineering with UML, Component Series, Addison-Wesley, 2001

– I. John and M. Eisenbarth, "A decade of scoping: a survey," in Proceedings of the 13th International Software Product Line Conference, ser. SPLC '09. Pittsburgh, PA, USA: Carnegie Mellon University, 2009, pp. 31-40.

– J. Lee and D. Muthig, "Feature-oriented variability management in product line engineering," Commun. ACM, vol. 49, no. 12, pp. 55-59, Dec. 2006.

– D. Muthig and C. Atkinson, "Model-Driven product line architectures," in Software Product Lines, ser. Lecture Notes in Computer Science, G. Chastek, Ed. Berlin, Heidelberg: Springer Berlin / Heidelberg, Jul. 2002, vol. 2379, ch. 8, pp. 79-90.

– K. Pohl, G. Böckle, and F. J. Linden, Software Product Line Engineering: Foundations, Principles and Techniques. Secaucus, NJ, USA: Springer-Verlag New York, Inc., 2005.

– D. Weiss and C. Lai. Software Product Line Engineering - A Family-Based Software Development Process, Addison-Wesley, 1999


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Motivation: Typical Challenges

� For System-Developing Organizations

– Series of development projects (leverage on commonalities, reuse)

– Increasing complexity of systems (avoid complexity explosion)

– Need for reducing cost, effort, and time-to-market (can be reduced via reuse)

– Increasing request for quality solutions (certification hard w/o reuse)

– Increasing demand for customized products (easy adaptation if anticipated)


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Variability in Time vs. Variability in Space [bachmann+05]

� Variability

– the ability of a core asset to adapt to usages in the different product contexts that are within the product line scope

� Variability in Time ( releases, dominant in IS )

– the existence of different versions of an artifact that are valid at different times

� Variability in Space ( variants, dominant in ES )

– the existence of an artifact in different shapes at the same time


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture What is "Software Product Line Engineering" (SPLE)?

� Software Product Line Engineering

– a paradigm to develop software applications using platforms and mass customization. [Pohl+05]

� Family/Domain Engineering (creating reusable artifacts)

– the process of software product line engineering in which the commonality and the variability of the product line are defined and realized. [Pohl+05]

� Application Engineering (creating customer applications from reusable artif acts)

– the process of software product line engineering in which the applications of the product line are built by reusing domain artifacts and exploiting the product line variability. [Pohl+05]

= +

SPLE

P2

Family Engineering

P2

Application Engineering

P2P1 P3


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Life Cycle of a Software Product Line


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture

Product Line Infrastructure

Domain

Product Line Life Cycle

Domain

Family Engineering

ProductLine

Artifact Base

Feedback

Documentation

Identification

Classification Evolution

Coordination

Evaluation

Integration

Adaptation

Application Engineering

ProductRequirementsProduct

Requirements

Requirements CRequirements B

Product Requirements A


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Scoping

� Product Line Scoping is the process of identifying and bounding capabilities(products, features) and areas (subdomains, existing assets) of the product line where investment into reuse is economically useful and beneficial to product development. [John+09]

[John+09]


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Scoping Example

� Product Feature Matrix


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Variation in Space x Time x Lifecycle

[Biglever: The Systems and Software Product Line Li fecycle Framework ]


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Goals of Software Product Line Engineering

� Reduction in the time to market required for indivi dual products

� Reduction in required development effort per applic ation (product)

� Reduction in overall development effort per product line

� Increase in quality

� etc. [Weiss+ 99]


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Product Line Economics – Development Effort

# Delivered System1 2 3 4 5 6

Effort

SingleSystem

Investment

PL Instance

Single System Development

Product LineApproach

Rule of thumb: Savings begin between 2nd

and 3rd product.Rule of thumb:

Investment ranges

between development efforts for 1

and 2 systems.

[Weiss/Lai], [Fraunhofer PuLSE™], etc.


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture

# Delivered Products1 2 3 4 5 6

Single-systemDevelopment (independent)

PL Engineering(proactive)

PL Engineering(reactive)

Single-systemDevelopment

(clone-and-own)

SuccessfulProduct Lines

Product Line Strategy – Product Line Economics (Revi sited)

Effort(~ TTM-1

~Cost)


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture SW Architecture

� Architecture is the first artifact that translates the problem into in the solution space

� Provides an overview on the system

� Enables early discussion and assessment of design a lternatives

� Architecture is the output of the software design p rocess


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture PL System Architecture as a Mediator

� Specification & decomposition of a whole family of systems

– covering the most important common design decisions

– supporting SW variations for system customization

� Constraints & guidance of PL Implementation

– allowing parallelization of work in family and application engineering

– ensuring that the quality attributes can be achieved in all members of the PL


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture What offers a product line architecture?

� Enables making considerations about variability early on

� Product Line Architecture enables encapsulating the variability

[Mann+ 09]


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Architectural Drivers

� Business goals

– Customer organization

– Developing organization

� Quality attributes

– System in use

– System under development

� Key functional requirements

– Unique properties

– Make system viable

� Constraints

– Organizational and technical

– Cost and time


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Architecture Usage Scenarios

and who are the stakeholders?


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Architecture stakeholders

General Architecturestakeholders

Additional Architecturestakeholders in a PL


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Fraunhofer Architecture Process


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Planning

� Incremental definition of an architecture

– Align with project plan

→ System increments

→ Availability of necessary non-software components or artifacts

– First iteration typically addresses complete systems at a high level of abstraction (conceptual view)

� Scope of Iterations

– Document all required decisions (revisit if backtracking is necessary)

– Constrain decisions as little as possible (but as much as necessary)


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Realization

� Refining quality requirements

– Define main qualities

– Identify categories of requirements

– Identify and apply architectural scenarios

� Identifying subsystems, components, and connectors

– Check consistency, conformity, and completeness with respect to quality requirements

– Handling of constraints and alternatives

� Analyzing and mitigating risks

– Prototyping

– Reverse Engineering

� Recording of design decisions and rationales


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Documentation: Views, Models, Diagrams

� Architectural View

– A representation of a system from the perspective of a related set of concerns

� Benefits

– Separation of Concerns

– Complexity reduction

– Communication with stakeholders

Idea: View-based Design and Analyses


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Variation Modeling in UML

� Unified Modeling Language (UML) is commonly used to describe software architectures — at least for object-oriented systems

� UML does not support the description of PLAs

– UML tools do not support it, either

– some UML tools support UML extensibility mechanisms

→ Stereotypes

→ Tagged Values (Properties)

→ Constraints

→ Find a workaround using UML extensibility options

– allows to use existing tools

– product line architectures comply to the UML standard


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Typical variant elements in UML


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Feature Modeling

� Feature modeling

– is the activity of identifying externally visible characteristics of products in a product line and organizing them into a feature model. [Lee+06]

� Features

– can be services, operations, non-functional characteristics, and technologies of a particular product line. [Lee+06]

Type

Car

[1..1]

Truck

Engine

DieselElectricity

[1..1]

Petrol

WheelTrunk Seat

Vehicle

Mandatory

Optional

Alternative [min..max]

Variability Dependencies

requiresexcludes

Constraint Dependenciesrequires

excludes


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Decision Modeling

� Decisions

– are variation points that typically constrain the resolution of other variation points. [Muthig+02]

� Each Decision defines a question that capture s the essence of the related variability

� A Decision Model includes

– id

– decision name

– question

– variation point

– resolution & default


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture KobrA – Generic Component Model Suite

� KobrA

– a systematic method that integrates component-based development with product line engineering [Atkinson+01]

– makes use of the extension mechanisms of the UML [Muthig+02]


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Basic Goals [Atkinson+01]

� Simple

– a method with separate concerns

� Systematic

– concepts and guidelines defined in the method should be precise and unambiguous

– tell developers what they should do, rather than what they may do

� Scalable

– be able to accommodate large-scale and small-scale problems in the same manner

– the method should be applicable incrementally

� Practical

– compatible with commonly used technologies


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Role of a Component Specification

� To describe the externally visible properties of a component

� Defines a component’s

– supplied services (supplied interface)

– acquired services (components)

� Provides the basis for the contract between the com ponent and its clients

� Is defined in the context of the parent component’s realization (or the context realization if the root)


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Primary Specification Models

� Structural model

– data manipulated by the component, its environment, and any externally visible structure

– one or more class diagrams

– zero or more object diagrams

� Functional model

– computations performed by the component

– one operation specification for each operation

� Behavioral model

– states exhibited by the component and the events that change them

– zero or more state chart diagrams


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Example: Structural Model


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Example: Functional Model


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Example: Behavioral Model


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Role of a Component Realization

� To describe the way in which a component realizes t he services specified in the specification

� Defines a component’s

– private subcomponents

– architecture and design

� Is defined in the context of the component’s speci fication

– the realization models expand upon the information in the specification model


�Defintion

�Life cycle

�Goals


�Usage

�Process


�Feature Model

�Decision Model





SW Product Line Architecture Example: Phone Component

Documents

Winter Term 2011/12 Prof. Dr. Dr. h. c. Dieter Rombach ......Winter Term 2011/12 Prof. Dr. Dr. h. c. Dieter Rombach Chapter 5.4: Software System Engineering - Software Product Line