1 SA Capstone Requirements and Design Week 6 SYST36367 - Winter 2015 Some slides adapted from:...

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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

Agenda

• Schedule Reminder– Requirements Deliverable Due next week– Remainder of the schedule remains intact

• Next Deliverable – Design Document Due Week 10• Worth 30%

• Review Design Document • Mandatory Team Meetings Today

Design Document (Deliverable 3)

• Worth 30%

Systems Analysis and Design in a Changing World, 6th Edition 4

Analysis Objectives versus Design Objectives

Understand WHAT is required

Design HOW to meet requirements


Analysis vs. Design Models


UML Requirements vs. Design Models

Diagrams are enhanced and extended


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

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


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



Hosting Alternatives for Internet Deployment Hosting:

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

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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.


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


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


Controller Pattern

First step toward multilayer architecture

More design patterns are at the end of the chapter


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


Start with Domain ClassDiagram

RMO Sales Subsystem


Create First Cut Design ClassDiagram

Use Case Create phone sale with controller added


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


Start with System Sequence Diagram (SSD)

Use case Create customer account


Sequence Diagram to show View Layer and Part of Problem Domain Layer


Create Customer Account Use Case

Start with domain model for Customer Account Subsystem



First cut design class diagram for use case

Select needed classes, elaborate attributes, add controller, and add navigation visibility



First cut sequence diagram expanding SSD, adding controller, and adding needed classes



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


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


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.


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.

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Group Meetings We will be meeting with each group today to assess

your progress and provide some advice

1 SA Capstone Requirements and Design Week 6 SYST36367 - Winter 2015 Some slides adapted from:...

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