1 SA Capstone Requirements and Design Week 6 SYST 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

Systems Analysis and Design in a Changing World, 6th Edition 5 Analysis vs. Design Models

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 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 Systems Analysis and Design in a Changing World, 6th Edition 8

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Systems Analysis and Design in a Changing World, 6th Edition 11

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 12

Systems Analysis and Design in a Changing World, 6th Edition 13 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

14 Software Components and Frameworks F Time to Market is paramount in today’s competitive marketplace F Selecting powerful and tested frameworks and components can save lots of development time F Systems Analysts often need to participate in “Buy versus Build” decisions regarding components and frameworks F 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! F 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.

Systems Analysis and Design in a Changing World, 6th Edition 15 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 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 Controller Pattern First step toward multilayer architecture More design patterns are at the end of the chapter

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

Systems Analysis and Design in a Changing World, 6th Edition 20 Create First Cut Design Class Diagram Use Case Create phone sale with controller added

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 Start with System Sequence Diagram (SSD) Use case Create customer account

Systems Analysis and Design in a Changing World, 6th Edition 23 Sequence Diagram to show View Layer and Part of Problem Domain Layer

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

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

Systems Analysis and Design in a Changing World, 6th Edition 26 Create Customer Account Use Case First cut sequence diagram expanding SSD, adding controller, and adding needed classes

Systems Analysis and Design in a Changing World, 6th Edition 27 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

Systems Analysis and Design in a Changing World, 6th Edition 28 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.

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