3-Analysis and Design Overview

12 Architect Software Architecture Document Reference Architecture Analysis Model Design Model Deployment Model Implementation Model... Designer’s Responsibilities.[r]

Analysis and Design Overview

 Review the key Analysis and Design terms and concepts

 Introduce the Analysis and Design process,

including roles, artifacts and workflow

 Explain the difference between Analysis and Design

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Analysis and Design in Context

The purposes of Analysis and

Design are to:

into a design of the

system-to-be

 Evolve a robust architecture

for the system

 Adapt the design to match

the implementation

environment, designing it for

performance.

The purposes of Analysis and

Design are to:

into a design of the

system-to-be

 Evolve a robust architecture

for the system

 Adapt the design to match

the implementation

environment, designing it for

performance.

Analysis and Design Overview

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Supplementary Specification

Data Model

Architecture Document

Analysis and Design

Glossary

Analysis Versus Design

Analysis and Design Are Not Top-Down

What Is Architecture?

 Software architecture encompasses a set of significant decisions about the organization of

a software system.

interfaces by which a system is composed

elements

elements into larger subsystems

Grady Booch, Philippe Kruchten, Rich Reitman, Kurt Bittner;

Rational (derived from Mary Shaw)

Architecture Constrains Design and

Architecture decisions are the most fundamental decisions,

and changing them will have significant effects

Architecture

Design Implementation

Code

Software Architecture:

The “4+1 View” Model

Process View Deployment View

Performance, scalability, throughput

System integrators System topology, delivery,

installation, communication

System engineering

Analysts/Designers

Structure

Analysis and Design Workflow

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Analysis

Design

[Early Elaboration Iteration]

[Inception Iteration (Optional)]

Define a Candidate Architecture ArchitecturalPerform

Synthesis

Analyze Behavior

Refine the Architecture

Design Components Design theDatabase

(Optional)

Analysis and Design Activity Overview

Architect

Designer

Software Architect’s Responsibilities

Reference Architecture

Analysis Model

Design Model

Deployment Model Implementation Model

Analysis and Design Is Use-Case Driven

 Use cases defined for a system are the basis for the entire development process.

 Benefits of use cases:

of stakeholders.

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Withdraw Money

Check Balance

Customer

What Is a Use-Case Realization?

Class Diagrams Use Case

Communication Diagrams Sequence

Diagrams

Analysis and Design

in an Iterative Process

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Iteration n Iteration n + 1

Use Case A Scenarios 1 & 2

Use-Case Realization A Start of iteration

End of iteration

Use Case B Scenario 1

Use-Case Realization A

Use Case A Scenario 3

Use-Case Realization B

 What is the purpose of the Analysis and

Design Discipline?

 What are the input and output artifacts?

 Name and briefly describe the 4+1 Views of Architecture.

 What is the difference between Analysis and Design?

 What is architecture?

Architectural Analysis

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Objectives: Architectural Analysis

 Explain the purpose of Architectural Analysis and where it is performed in the lifecycle.

 Describe a representative architectural

pattern and set of analysis mechanisms, and how they affect the architecture.

 Describe the rationale and considerations

that support the architectural decisions.

 Show how to read and interpret the results of Architectural Analysis:

Architectural Analysis in Context

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[Early Elaboration Iteration] Iteration (Optional)][Inception

Define a Candidate Architecture ArchitecturalPerform

Synthesis

Analyze Behavior

Refine the Architecture

Design Components Design theDatabase

(Optional)

Architecture

Analysis

Architect

Architectural Analysis Overview

Design Model

Reference Architecture

Deployment Model

Vision Document

Software Architecture Doc

Project-Specific

Guidelines

Architectural Analysis Steps

 Key Concepts

model

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The “4+1 View” Model

Process View Deployment View

Performance, scalability, throughput

installation, communication

System engineering

Analysts/Designers

Structure

Review: What Is a Package?

 A package is a general-purpose

mechanism for organizing

elements into groups.

 It is a model element that can

contain other model elements.

 A package can be used

Package Relationships: Dependency

Hierarchy should be acyclic

Circular dependencies make it impossible

to reuse one package

without the other.

Avoiding Circular Dependencies

A

B

C

A' C

A

B

A

B

Architectural Analysis Steps

 Define the High-Level Organization of the

model

Patterns and Frameworks

details may be Analysis/Design patterns

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What Is a Design Pattern?

 A design pattern is a solution to a common design problem.

 Describes a common design problem

 Describes the solution to the problem

 Discusses the results and trade-offs of applying the

What Is an Architectural Pattern?

 An architectural pattern expresses a

fundamental structural organization schema for software systems It provides a set of predefined subsystems, specifies their responsibilities, and includes rules and guidelines for organizing the relationships between them – Buschman et al,

“Pattern-Oriented Software Architecture — A

Typical Layering Approach

General

functionality

Specific

an application — contains the value adding software developed by the organization.

Business specific — contains a number of reusable subsystems specific to the type of business.

Middleware — offers subsystems for utility classes and platform-independent services for distributed object computing in heterogeneous environments and so on.

System software — contains the software for the actual infrastructure such as operating systems, interfaces to specific hardware, device drivers, and so on.

Application

Business-Specific

Middleware

System Software

Detects and corrects errors in bit sequences Transmits bits: velocity, bit-code, connection, etc.

Layering Considerations

 Group elements at the same level of abstraction

 Group like things together

 Separate disparate things

 Application vs domain model elements

 Loose coupling

 Concentrate on encapsulating change

 User interface, business rules, and retained data tend to have

a high potential for change

Modeling Architectural Layers

 Architectural layers can be modeled using

What Are Stereotypes?

 Stereotypes define a new model element

in terms of another model element.

 Sometimes you need to introduce new

things that speak the language of your

domain and look like primitive building

blocks.

Class

<<stereotypename>> Stereotype

High-Level Organization of the Model

Architectural Analysis Steps

model

 Identify Analysis mechanisms

What Are Architectural Mechanisms?

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Required

Functionality

Implementation Environment

Architect

Supplementary

Specification

Use-Case Model

Mechanisms COTS Products Databases

IPC Technology, etc.

“realized by client classes using”

“responsible for”

“constrained by”

Architectural Mechanisms: Three Categories

 Architectural Mechanism Categories

Why Use Analysis Mechanisms?

That is why we have a persistence analysis mechanism We don’t know enough yet, so we can bookmark it and come back to it later.

Analysis mechanisms are used during analysis to reduce the

complexity of analysis and to improve its consistency by providing

designers with a shorthand representation for complex behavior.

Sample Analysis Mechanisms

Examples of Analysis Mechanism Characteristics

Example: Analysis Mechanism Characteristics

 Legacy interface mechanism

Describing Analysis Mechanisms

 Collect all analysis

Analysis Mechanisms

Example: Course Registration Analysis

Mechanisms

Persistence Distribution

Architectural Analysis Steps

model

 Identify Key Abstractions

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What Are Key Abstractions?

 A key abstraction is a concept, normally

uncovered in Requirements, that the system must be able to handle

 Sources for key abstractions

Defining Key Abstractions

 Define analysis classes

 Model analysis classes and relationships on

Example: Key Abstractions

Student Professor

Schedule

Architectural Analysis Steps

model

 Create Use-Case Realizations

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What Is a Use-Case Realization?

Use-Case Model Design Model

Class Diagrams Use Case

Communication Diagrams Sequence

Diagrams

The Value of Use-Case Realizations

 Provides traceability from Analysis and Design back to Requirements

 The Architect creates the Use-Case

Architectural Analysis Steps

model

 Checkpoints

 General

done in a logically consistent way?

been identified?

 Packages

picture of the services of the packages in

upper-level layers?

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Checkpoints (continued)

 Classes

relationships been identified and

accurately modeled?

reflect the role it plays?

their relationships consistent with the

Business Model, Domain Model,

Requirements, Glossary, etc.?

Review: Architectural Analysis

typical layers.

Architectural Analysis? Why are they identified

here?

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Exercise: Architectural Analysis

 Given the following:

discipline: (Exercise Workbook: Payroll

Requirements)

Workbook: Payroll Architecture

Handbook, Logical View, Architectural

Analysis)

layers and their dependencies

Exercise: Architectural Analysis

(continued)

 Identify the following:

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Exercise: Architectural Analysis

(continued)

 Produce the following:

architectural layers and their dependencies

Exercise: Review

 Compare your key abstractions

with the rest of the class

identified?

the role it plays?

 Compare your class diagram

showing the upper-level layers

the Payroll System architecture?

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