1. Impact of Agile Methodology on Software Architecture
Hessam Modaberi | Software Architecture course

2. Agenda 01 | Agility through Scrum Framework 02 | Architectural Agility
03 | Dependency Injection

3. 01 | Agility through Scrum Framework

4. Why Agile? Two potential waterfall problems Freeze Requirements
Building an architecture for emergent problem space is difficult
Considerable effort before delivering any feature to user

5. What is Agile development ?
Agile SDLC model is a combination of iterative and incremental process model
Requirements

6. Definition of Scrum
Scrum (n): A framework within which people can address complex adaptive problems, while productively and creatively delivering products of the highest possible value.

7. Scrum Theory
Scrum is founded on empirical process control theory, or empiricism
Three pillars:
Transparency (definition of DONE)
Inspection
Adaptation

8. The Sprint
The heart of Scrum, a time-box of one month or less during which a “Done”, useable, and potentially releasable product Increment is created.
(Iteration)

9. Product Backlog and Spring Backlog
PBI
The Product Backlog lists all features, functions, requirements, enhancements, and fixes that constitute the changes to be made to the product in future releases.
The Sprint Backlog is the set of Product Backlog items selected for the Sprint.
Product Backlog

10. Scrum Team
Product Owner - is the sole person responsible for managing the Product Backlog
Development Team – 3 to 9 team members
Scrum Master - is responsible for ensuring Scrum is understood and enacted
Two Scrum team characteristics :
self-organizing
cross-functional

11. Scrum Events Sprint Retrospective All events are time-boxed events
Duration: 3 hours
All events are time-boxed events
One month sprint
Spring planning
Duration: 8 hours
Sprint Review
Duration: 4 hours
Daily Scrum
Duration: 15 min
Input to this meeting:
Product backlog
Latest product increment
Capacity of dev team
Any impediments?

12. 02 | Architectural Agility

13. The Challenge
The critical role of the underlying architecture is often overlooked
Enhancement Agility: the ability to keep adjusting the product to emerging needs through the addition of new features.
Agile approach has its shortfalls stemming mainly from dependency analysis:
Individual stories cannot be regarded in isolation
Stories have dependencies upon the architectural elements of the system.

14. Problem Demonstration (Example)
Authentication and Authorization with ACL, leads to change Security Arc component
Business need (Sprint 1): System users have different accesses based on their roles

15. Problem Demonstration (2)
Business need changes (Sprint 2): Users have access based-on their permissions

16. Result of preceding approach
Too-familiar situation
features gradually take longer and longer to implement
code becomes more and more buggy
Eventually, the system must be scrapped and rewritten “from scratch”

17. Architectural Agility
A Thesis from Carnegie Mellon University and Software Engineering Institute (SEI)
Architectural Agility allows architectural development to follow a “just-in-time” model.
A steady and consistent focus on continuing architectural evolution in support of emerging customer-facing features (instead of myopic focus on user stories).

18. Architectural Agility (2)
Without Architectural Agility, Enhancement Agility cannot be reliably sustained.
Truly optimizing user value requires teams to look ahead and anticipate future needs
The architecture should not over-anticipate emergent needs, delaying delivery of user value and risking development of overly complex and unneeded architectural constructs

19. Architectural Agility (3)
Architectural anticipation must be “informed.
“informed anticipation” can be achieved through:
Dependency Analysis
Real-option Analysis
Technical debt

20. Agile Release Planning
Architectural Elements in Agile Iteration planning

21. Architecture Dependency Management
Dependency Structure Matrix
(DSM)
Domain Mapping Matrices
(DMM)

22. Real-option Analysis and Technical debt Management
Technical debt: The extra development work that arises when code that is easy to implement in the short run is used instead of applying best overall solution.
In agile release planning, real options analysis is a way to look at the allocation of architectural elements to releases based on their dependencies from the perspective of future value.

23. Architecture Heuristics
while not required for the current release, should potentially be incorporated into the current release in anticipation of future stakeholder goals.

24. 03 | Dependency Injection

25. Why Dependency Injection?
Often, Agile projects are rapidly fielded!
Ward Cunningham:
“ Dependency injection is a key element of agile architecture”

26. Data Access Object (DAO)
Presentation
CostomerService addCustomre(..)
Has following dependencies :
createCustomer(..)
createAuthority(..)
doTask3(..)
doTask4(..)
Business Layer
Service
CustomerDao
createCustomer(..)
Data Layer
Data Access Object (DAO)
AuthorityDao
createAthority(..) DB

27. Dependent Classes Bridge Design Pattern Interface A Class 2 implements
Class 1 uses class 2 through Interface A
Class 1
Class 2
Class 1 depends on Class 2
Server
Client
These two classes are loosely coupled classes

28. Dependency Injection Explanation
public class TextEditor {
private SpellChecker spellChecker;
public TextEditor() {
spellChecker = new SpellChecker(); }

29. Dependency Injection Explanation (2)
public class TextEditor {
private SpellCheckerInterface spellChecker;
public TextEditor(SpellCheckerInterface spellChecker ) {
this.spellChecker = spellChecker; }

30. DI in Java Spring IoC Container
Context Dependency Injection (Oracle Standard)

31. Thank you!