1. Software Architecture
Chris “Big horn” Horne,
Nolan “N-thug” kelly,
Nairn “BAker” Tsang,
dave “chocolate milk” ryan,
sean “whacky hat” boyd,
Mark “The whopper” D’Adamo

2. Table of Contents Introduction Message Bus Architecture
Client Server Architecture
Object Oriented Architecture
N-Tier Architecture
Component Based Architecture
Layered Architecture

3. What is Software Architecture?
High level structures of a software system.
Also denotes the set of practices used to select, define or design a software architecture.
WOW

4. Message Bus Architecture

5. Message Bus Architecture – The Problem
Maintaining point to point links between an increasing number of nodes
Complex
Expensive
Decentralized

6. Message Bus Architecture – The Solution
Message Oriented Middleware
Extra component to handle inter-nodal communication
Publish and Subscribe
List Based
Message bus filters subscribers
Broadcast Based
Subscribers filter messages

7. Message Bus Architecture - Advantages
Reduced Application Complexity
Communication complexity localized in bus
Modules need only follow protocol
Improved Modifiability
Adding messages or components is simple
Improved Performance
Removal of intermediaries
Improved Scalability
New components have no impact on older ones

8. Message Bus Architecture – Disadvantages
Increased Complexity
All connected parties must follow bus conventions
Lowered Modifiability when breaking bus interface
Changing the bus interface requires changes to every component that uses it
Lowered Security
Broadcast based pub / sub sends messages indiscriminately
Low Tolerance for downtime
The bus becomes a single point of failure

9. Message Bus Example – D-BUS
Open source IPC system for Unix
Also offers communication channel between user sessions and hardware
Communication through sockets
Implements pub/sub

10. Client Server Architecture

11. Overview Prevailing model in network programming Two roles
Client
Server
Clients and servers are physically
located on different machines
Require remote access to communicate

12. Server Manage a set of resources Ideally active at all times
Service many clients at a time

13. Client Single user host system Initiate contact with the server
Clients never communicate directly with other clients

14. Types of Client-Server Architecture
2-Tier
Presentation logic on client side
Data services on server side
Business logic location varies
3-Tier
Middleware introduced that handles business logic
N-Tier
More detailed
divisions of logic

15. Fat/Thin Clients Fat Client Thin Client
Client performs majority of data and processing operations
Client can perform many functions
without connection to server
Thin Client
Client does as little processing as possible
Relies on accessing server very often

16. Pros/Cons Pros Cons Centralization of data Congestion Security Cost
Not Robust

17. Example – Microsoft SQL Server
Database application
Servers are large computers stored at a centralized location
Many applications can connect to server and make requests for data

18. Object Oriented Architecture

19. Overview System as a group of interacting objects
Objects are defined by:
Class
Attributes (Data Fields)
Behaviour (Methods)
Objects interact with each other by passing messages

20. Fundamental Features Data hiding (Encapsulation) Inheritance
Abstraction
Polymorphism

21. Pros/Cons Pros Cons Closer to how we view real world problems
Requires planning
Reusable code
Not appropriate in all situations
Extensibility
Maintainability

22. Example – Cocoa Apple’s native API Objective C (OOP language)
Model-View-Controller

23. N-Tier Architecture

24. 3-Tier, The Most Common

25. Benefits
Maintainability
Scalability
Flexibility
Availability

26. Weaknesses
Bloat
Inflexibility

27. Examples
3-Tier Architecture suits e-commerce extremely well

28. Component Based Architecture
By: prof. Dr. Franz j. bilkingtonrobinowitzfredrickshaven

29. Overviews Focuses on decomposing software into logical components
Components are loosely coupled
Higher level of abstraction than OOP for example.
Does not focus on communication protocols and shared state
“Hand Crafting” vs. “Mass Production”
So what are components?
FUCK

30. I’m Glad You Asked!
Any software package/module that encapsulates a related set of functions/data
Want to encapsulate the component to where no knowledge of it’s internal workings is needed. Low Coupling
Provides functionality with a provided interface (specifies what a component can provide to other components in the system)
Example: A Button! Provides event-on-mouse-click, event-on-mouse- hover, etc. Without knowing how the button works!
Because buttons! How do they work?

31. Hand Crafted vs. Mass Produced
Time consuming. Each line of code is lovingly typed by the finest code-smiths for the singular purpose of the current project.
If you make a mistake(ex. wrong requirements, 471 amirite?!)…
…your project can be done for good (WWI guns)
…your project is going to be expensive to fix. (Lamborghini expensive)
Not time consuming. Each line of code may have been coded a long time ago but it still works as it needs to today.
Easy to fix…
Because of the low coupling of your modules, and the fact that they communicate via interfaces, a bad module can be substituted for a good one. Saves time and money.
Think Lego…

32. A Note About the Last Slide
The most important thing to take away from this is quality.
Hand crafting does not always yield a higher quality product
You can hand-craft a mess just as easily as you could mass-produce genius.
Quality will be determined… BY THE IRON TRIANGLE
CBA helps with the Schedule and Resources aspects

33. Exquisite Qualities And Abhorrent Attributes
Pros
Cons
Ease of Deployment
Reduced Cost
Ease of Development
Reusable
Mitigation of technical complexity
Message Handling
Reliance on Third Parties
Testing can be messy
Second System Syndrome

34. VIDEO GAMES - Then Games were comparatively simple back in the day
Name Dropping:
Games were comparatively simple back in the day
Programmed in an Inheritance based programming style
Good for smaller, more simple games
Adds tons of complexity as game content increases.
(Multiple Inheritance)

35. VIDEO GAMES - Now Games today are massive and extremely complex.
More Name Dropping:
Games today are massive and extremely complex.
Bigger focus on open world games where you can do whatever you want
Gamers always want more
This want creates the need for something better than IBP
Observe…

36. Inheritance Based Programming
Take this generic container for example:
Say we want to make it a chest…
But let’s say gamers demand that said chest become a witty sidekick that follows you around everywhere and makes sarcastic remarks as well…
Boom…
Multiple inheritance! OH NOES

37. VIDEO GAMES - Now CBA to the rescue!
Instead of creating a generic game object class with limited functionality and adding to it via class specialization…
Just make a generic game object class with the ability to add features as needed to reduce the complexity of the system.
Yay progress!!

38. Layered Architecture

39. What is it?

40. Advantages Abstraction Encapsulation High cohesion Reusable
Loose coupling
Design Pattern Support

41. Disadvantages Doesn’t work for all systems Start to lose advantages
Can end up with low cohesion and high coupling

42. Now go away or I shall taunt you a second time
FIN.
Now go away or I shall taunt you a second time