1. Software Architecture & Design
6CCS3SAD / 7CCSMDAS
Dr Kevin Lano

2. Module Overview

3. What is an architecture?
Coarse grained view of a system:
Main components and component relations
Middleware decisions
Distribution structure
Heterogeneous
links to external systems running on different platforms/middleware are often present
Structure considered first class artefact
Not a fine-grained view of a system process
UML use-case or a statechart or pseudocode
 5CCS2OSD dealt with these
21/01/2016
(c) Steffen Zschaler

4. Why is it important? How architectural designs help:
Aid to project management
top-down development
components are assigned to different teams
Centralized coordination of how everything should fit together
Decisions about middleware, platforms, structure
Non-functional properties of systems
Performance, reliability, security, ...
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(c) Steffen Zschaler

5. Why is it important? (2) Many systems end in disaster because
Architecture is given a limited role
Architecture becomes a factor too late in development
Hacked up structures are difficult to maintain and scale
during and after development
Hacked up architectures often lead to functional and non-functional problems
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(c) Steffen Zschaler

6. Therefore...
Software architects some of the most important people in software projects
versus
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(c) Steffen Zschaler

7. Learning Objectives At the end of this module you should be able to
Function as a software architect
Explain a broad range of issues, techniques and processes involved in architecture design
Design medium to large size software systems
Use the UML2 effectively to design architectures
Work with and design metamodels and frameworks
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(c) Steffen Zschaler

8. Pet store example Online pet store sells animals to customers
A web site for customers
Different classes of other users
Admins, external businesses (e.g., suppliers), vets
Access to specific categories of functionality
Interact with application through specific interfaces
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(c) Steffen Zschaler

9. Pet Store Example Architecture
JSP
EJB
.NET web services
Pet Store Web Site (Front End)
Order Fulfilment
Supplier
Customer
Credit Card Services
Other Suppliers
Full architecture expands these components to define their structure
For example, order fulfilment involves several components encapsulating business logic
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(c) Steffen Zschaler

10. Bad Architecture  Poor Scalability, Maintenance
Customer
Petshop
website
(including
order fulfilment)
Database
Architecturally unsound
All business logic coded up in the website presentation tier
Difficult to maintain – concerns are all mixed together
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(c) Steffen Zschaler

11. Bad Architecture  Poor Performance
Web Site
Hotel Reservation
Credit Card Banking
Car Reservation
Air Reservation
Data Management (Server)
Direct connection of client component to multiple server components (several reasons why this style of architecture is flawed)
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(c) Steffen Zschaler

12. Good architecture  Better Performance
Holiday
Reservation
Session
Web Site
Hotel Reservation
Credit Card Banking
Car Reservation
Air Reservation
Data Management
Business Logic
Server
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(c) Steffen Zschaler

13. Beyond Boxes and Lines
Good architectural designs don’t solve all architectural issues
Role of software architect includes
Reuse of good architectural patterns
Domain-specific meta-modelling
Product lines – architectural families
Model-driven programming – programming through architectures
We will look at some of these, too
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(c) Steffen Zschaler

14. Course Details Prerequisites Lectures
Introductory UML, programming experience
Lectures
Mondays 10am to 12.00; room K4.U12
From 4th February, starts with 1 hour of tutorials from 9am–10am
exercises
discussions
group work
 Tasks and details on KEATS
21/01/2016
(c) Steffen Zschaler

15. Assessment Exam worth 100% of final grade Two parts – easy and hard
First part (40%) tests basic understanding of learning outcomes
Second part (60%) assesses deeper level of skills and understanding
Level 7 exam different from Level 6, also pass-mark is 50% instead of 40%
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(c) Steffen Zschaler

16. Questions All material is on KEATS Email: kevin.lano@kcl.ac.uk
Office hours,
Tuesdays 1.30pm–3.30pm,
BH N6.01
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(c) Steffen Zschaler

17. Recommended Reading
Mary Shaw and David Garlan: Software Architecture: Perspectives on an Emerging Discipline, Prentice Hall, 1996
Bass, Clements, and Kazman: Software Architecture in Practice, Addison-Wesley, 2003
Designing Software Architectures: A Practical Approach, 2016, Humberto Cervantes and Rick Kazman
John Cheesman and John Daniels: UML Components, Addison-Wesley, 2000
Warmer and Kleppe: The Object Constraint Language: Getting Your Models Ready for MDA, Addison-Wesley, 2003
Marco Brambilla, Jordi Cabot, Manuel Wimmer: Model-Driven Software Engineering in Practice, Morgan & Claypool, 2012
Kevin Lano, Agile Model-Based Development Using UML-RSDS , CRC Press, 2016.
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(c) Steffen Zschaler

18. Course Roadmap
Week 1: Overview, Basic Architecture Concepts Week 2: A Simple Process for Architecture Design Week 3: Compound Components, Basic Styles Week 4: More Styles, Complex Connectors Week 5/6: .NET Enterprise Services Week 7: Enterprise Styles + Deployment, Clouds, Containers Week 8: Object-Constraint Language (OCL) Week 9/10: Model-Driven Engineering Week 11: Revision
Abstract
Architecture
Concrete
Platforms
Physical Architecture
Using
Architectures