EENG 1920 Chapter 6 System Design II: Behavioral Models 1

Models Models - what do you think of? 2

Definitions Model – A standardized representation of a syst em Modeling Language – Letters and words – Graphical symbols Object Type – Blue prints – Diagram of a football play – Knitting instructions – Electrical schematics – Mathematical formulas 3

Properties of Models Abstract – Independent of final implementation – Multiple ways of implementing the design Unambiguous – A single clear meaning of intended behavior Allow for innovation Standardized – Common language that can be understood Facilitate good communication Modifiable 4

Properties of Models Remove unnecessary details – Show important features – Keep it simple Break system into sub-problems. Substitute sequence of actions by a single action Assist in verification – Model aiding in showing that the design met specifications 5

Flowchart Symbols 6

Example: Light Monitoring System 7

Example: Security Robot Requirements (loosely) 1.Must roam randomly around facility 2.Detect intruders by recognizing sound 3.Set-off an alarm if detects noise, transmit position, and wait. 4.Must regularly conduct a self-test to determine if it is working properly. Design Details 1.Has the three ultrasonic sensors and can measure distance to objects to the left, forward, and right. 2.Has a microphone that it uses to monitor sounds. 8

Data Flow Diagrams (DFD) Process – Describes a useful task – Performs a transformation on data Data flow – An arrow that represents a data relationship between two processes. Data stores: a data repository Interfaces – Sources – Sinks 9

Example: Video Browsing System 10

DFD – The Event Ta ble 11 EventTriggerProcessSource Annotate Video New Video Arrival Shot Boundary Detection System View Storyboa rd Browse Request Storyboard Preview User View ShotShot Preview Request Shot Preview User

Entity Relationship Diagrams (College Database ERD) 12

Unified Modeling Language (UML) (Scenario) Pretty popular idea – web ordering of groceries followed by home delivery. The “v-Grocer” system. User has a barcode scanner connected to home computer. They can scan a used item an automatically order it from the grocery store. Place the order and groceries delivered at pre-arranged time. 13

Static View (Class Diagram Notation) Object view of software. Classes represent – Data – Methods (functions) that operate on the data Objects are Can allow for different security levels. 14

Class Diagram 15

Use-Case View Captures overall behavior of the system from the user’s view Describes cases in which the system will be used 16

Use-Case Description 17 Use-Case Web-Order Actors Customer, Database, and WebServer DescriptionThis use-case occurs when a customer submits an order via the Web-Server. If it is a new customer, the Web-Server prompts them to establish an account and their customer information is stored in the Database as a new entry. If they are an existing customer, they have the opportunity to update their personal information. StimulusCustomer order via the Grocery-Cart. ResponseVerify payment, availability of order items, and if successful trigger the Assemble-Order use-case.

State Machine View 18

Activity View Intention = describe a sequence of activities needed to complete a task. 19

Interaction View Intention = to show interaction between objects (when they must cooperate to do something useful). Use either a collaboration or sequence diagram. This example is for the Web-Order use-case. 20

Physical View Show the physical components that constitute the system. Can think of this much more generally than presentation in UML. 21

Project Application: Selecting Models See Table 6.4 of book. Gives guidance on how to select models based upon behavior to describe. 22

Chapter 6 Homework 1. What is the definition of a model? 2. Name five Object Types of Models. 3. What is UML? 23