1. SA Capstone Requirements and Design Week 6 SYST36367 - Winter 2015
Some slides adapted from:
Systems Analysis and Design in a Changing World, 6th Edition, Satzinger, Jackson, Burd, CENGAGE Learning, 2012

2. Agenda Schedule Reminder Review Design Document
Next Deliverable – Design Document Due Week 10
Worth 30%
Review Design Document
Optional Team Meetings Today

3. Design Document (Deliverable 3)
Worth 30%

4. Analysis Objectives versus Design Objectives
Understand WHAT is required
Design HOW to meet requirements
Systems Analysis and Design in a Changing World, 6th Edition

5. Analysis vs. Design Models
The outputs of the Analysis phase become the input for the design phase
Systems Analysis and Design in a Changing World, 6th Edition

6. UML Requirements vs. Design Models Diagrams are enhanced and extended
Systems Analysis and Design in a Changing World, 6th Edition

7. Systems Analysis and Design in a Changing World, 6th Edition
Two Levels of Design
Architectural Design
Broad design of the overall system structure
Also called General Design and Conceptual Design
Detailed Design
Low level design that includes the design of the specific program details
Design of each use case
Design of the database
Design of user and system interfaces
Design of controls and security
Goal is to build well structured and MAINTAINABLE code
Get away from spaghetti code
Systems Analysis and Design in a Changing World, 6th Edition

8. Three Layer Architecture
Three Layer Client-Server Architecture
a client/server architecture that divides an application into view layer, business logic layer, and data layer
View layer
the part of the three-layer architecture that contains the user interface
Business logic layer or domain layer
the part of a three-layer architecture that contains the programs that implement the business rules and processes
Data layer
the part of a three-layer architecture that interacts with the data store
Systems Analysis and Design in a Changing World, 6th Edition

9. Systems Analysis and Design in a Changing World, 6th Edition

10. Systems Analysis and Design in a Changing World, 6th Edition
Michael Angelos Software Architecture
Systems Analysis and Design in a Changing World, 6th Edition

11. Systems Analysis and Design in a Changing World, 6th Edition
PCIM System Architecture
Systems Analysis and Design in a Changing World, 6th Edition

12. Design Activities: Design the system interfaces
Information systems interact with many other systems, internal and external
Much more integration now
System interfaces connect with other systems in many different ways
Save data another system uses
Read data another system saved
Real time request for information
Software services
Systems Analysis and Design in a Changing World, 6th Edition

13. Hosting Alternatives for Internet Deployment
Running and maintaining a computer system on someone’s behalf where the application software and the database reside
The process of providing physical servers at a secure location and selling those services to other businesses that wish to deploy Web sites
Issues when considering hosting alternatives
Reliability, security, physical facilities, staff, potential for growth and cost
Consider making sure your hosting is done on Canadian servers to ensure your data is subject to Canadian laws
Systems Analysis and Design in a Changing World, 6th Edition

14. Software Components and Frameworks
Time to Market is paramount in today’s competitive marketplace
Selecting powerful and tested frameworks and components can save lots of development time
Systems Analysts often need to participate in “Buy versus Build” decisions regarding components and frameworks
Capstone is designed to reflect industry best practices. So your team should look for components and frameworks that can speed your development and improve your product!
Past groups have used several components and frameworks including:
CakePHP, Yii, jQuery, Bootstrap, HTML5, PhoneGap, Google Web Toolkit (GWT), Microsoft Entity Framework, ASP.NET MVC, ASP.NET AJAX Control Toolkit, Crystal Reports, etc.

15. Systems Analysis and Design in a Changing World, 6th Edition
Design Patterns
Design Pattern—standard design techniques and templates that are widely recognized as good practice
For common design/coding problems, the design pattern suggests the best way to handle the problem.
They are written up in design pattern catalogs/references. Include:
Pattern name
Problem that requires solution
The pattern that solves the problem
An example of the pattern
Benefits and consequences of the a pattern
Systems Analysis and Design in a Changing World, 6th Edition

16. Systems Analysis and Design in a Changing World, 6th Edition
Design Patterns
Design patterns became widely accepted after the publication of Elements of Reusable Object-Oriented Software,(1996) by Gamma et al (the “Gang of Four”)
There are architectural design patterns talked about already
Three layer or model-view-controller architecture
The first example of a programming design pattern shown is the Controller Pattern.
Problem is deciding how to handle all of the messages from the view layer to classes in the problem domain layer to reduce coupling
Solution is to assign one class between the view layer and the problem domain layer that receives all messages and acts as a switchboard directing messages to the problem domain
Systems Analysis and Design in a Changing World, 6th Edition

17. Systems Analysis and Design in a Changing World, 6th Edition
Controller Pattern First step toward multilayer architecture More design patterns are at the end of the chapter
Reduce coupling between view layer and problem domain/business layer classes
Acts as a intermediary between outside world and internal system
Acts as a switchboard
Systems Analysis and Design in a Changing World, 6th Edition

18. First Cut Design Class Diagram
Proceed use case by use case, adding to the diagram
Pick the domain classes that are involved in the use case (see preconditions and post conditions for ideas)
Add a controller class to be in charge of the use case
Determine the initial navigation visibility requirements using the guidelines and add to diagram
Elaborate the attributes of each class with visibility and type
Note that often the associations and multiplicity are removed from the design class diagram as in text to emphasize navigation, but they are often left on
Systems Analysis and Design in a Changing World, 6th Edition

19. Start with Domain Class Diagram RMO Sales Subsystem
Further elaborate the attributes
Systems Analysis and Design in a Changing World, 6th Edition

20. Systems Analysis and Design in a Changing World, 6th Edition
Create First Cut Design Class Diagram Use Case Create phone sale with controller added
Denotes Navigation Visibility
Navigability often modelled as attributes (example Customer could have a collection each representing a Sale)
Controller classes are utility classes that help in the processing of a use case
Systems Analysis and Design in a Changing World, 6th Edition

21. Use Case Realization with Sequence Diagrams
Use case realization—the process of elaborating the detailed design of a use case with interaction diagrams
Two types of interaction diagrams
UML sequence diagram (emphasized in text)
UML communication diagram (also introduced)
Sequence diagrams, aka use case realization sequence diagrams, extend the system sequence diagram (SSD) to show:
View layer objects
Domain layer objects (usually done first)
Data access layer objects
Systems Analysis and Design in a Changing World, 6th Edition

22. Systems Analysis and Design in a Changing World, 6th Edition
Start with System Sequence Diagram (SSD) Use case Create customer account
Return messages in this case are simply for customer to verify…
Systems Analysis and Design in a Changing World, 6th Edition

23. Sequence Diagram to show View Layer and Part of Problem Domain Layer
Messages are method calls
data passed in is the parameters
Systems Analysis and Design in a Changing World, 6th Edition

24. Systems Analysis and Design in a Changing World, 6th Edition
Create Customer Account Use Case Start with domain model for Customer Account Subsystem
Systems Analysis and Design in a Changing World, 6th Edition

25. Systems Analysis and Design in a Changing World, 6th Edition
Create Customer Account Use Case First cut design class diagram for use case Select needed classes, elaborate attributes, add controller, and add navigation visibility
Honing down on the attributes
Systems Analysis and Design in a Changing World, 6th Edition

26. Systems Analysis and Design in a Changing World, 6th Edition
Create Customer Account Use Case First cut sequence diagram expanding SSD, adding controller, and adding needed classes
Note that Customer must have navigability to Address and Account
Systems Analysis and Design in a Changing World, 6th Edition

27. Systems Analysis and Design in a Changing World, 6th Edition
Create Customer Account Use Case Add messages and activation to complete collaboration This is just the domain layer These domain classes handle data access, so this is a two layer architecture
Use case realization
Get a good idea of the methods (and params) that have to be exposed
Customer object takes on responsibility for
Saving itself to the database
creating Address and Account classes directly  customer “owns” these classes (composition)
Systems Analysis and Design in a Changing World, 6th Edition

28. Systems Analysis and Design in a Changing World, 6th Edition
Assumptions
Perfect technology assumption—First encountered for use cases. We don’t include messages such as the user having to log on.
Perfect memory assumption—We have assumed that the necessary objects were in memory and available for the use case. In multilayer design to follow, we do include the steps necessary to create objects in memory.
Perfect solution assumption—The first-cut sequence diagram assumes no exception conditions.
Separation of responsibilities—Design principle that recommends segregating classes into separate components based on the primary focus, such as user interface, domain, and data access
Systems Analysis and Design in a Changing World, 6th Edition

29. Implementation Issues Three Layer Design
View Layer Class Responsibilities
Display electronic forms and reports.
Capture such input events as clicks, rollovers, and key entries.
Display data fields.
Accept input data.
Edit and validate input data.
Forward input data to the domain layer classes.
Start and shut down the system.
Systems Analysis and Design in a Changing World, 6th Edition

30. Implementation Issues Three Layer Design
Domain Layer Class Responsibilities
Create problem domain (persistent) classes.
Process all business rules with appropriate logic.
Prepare persistent classes for storage to the database.
Data Access Layer Class Responsibilities
Establish and maintain connections to the database.
Contain all SQL statements.
Process result sets (the results of SQL executions) into appropriate domain objects.
Disconnect gracefully from the database.
Systems Analysis and Design in a Changing World, 6th Edition

31. Group Meetings
We will be meeting with each group today to assess your progress and provide some advice