1. Analysis Modeling (cont’d) CpSc 372: Introduction to Software Engineering Jason O. Hallstrom jasonoh@cs.clemson.edu Authorship Disclaimer. These slides are intended to serve as teaching instruments for an undergraduate course in Software Engineering. While the slides were formatted by Dr. Hallstrom, the content is compiled from other sources, including the readings listed on the course website, Dr. Pressman’s Software Engineering textbook, and various internet materials. In almost every case, the ideas belong to someone other than Dr. Hallstrom. Indeed, text is often quoted verbatim without an explicit citation (to improve the readability of the slides). The original authors retain all copyrights. If you are interested in citing any of the material in these slides, please contact Dr. Hallstrom for the original source(s). DO NOT CITE THIS PRESENTATION. THE CONTENT SHOULD NOT BE ATTRIBUTED TO DR. HALLSTROM. SEE DR. HALLSTROM IF YOU HAVE ANY QUESTIONS.

2. CpSc 372 A Roadmap Use-cases Use-case diagrams Activity diagrams Swimlane diagrams Data object diagrams ERD diagrams Data flow diagrams Process specifications We are going to examine some of the key tools used for creating an analysis model. General Structured AnalysisOO Analysis Class diagrams Packages CRC cards Sequence Diagrams These tools are not specific to either structured analysis or OO analysis.

3. CpSc 372 Data Flow Diagrams Models data elements  Attributes  Relationships Models processes that transform data Structured Analysis: Data object diagrams ERD diagrams modeled using Data flow diagram Process narrative modeled using A data flow diagram describes information flow among a set of processes and actors. A process narrative describes how a single process transforms input data to output data. Modeling Tools: 1 *

4. CpSc 372 Data Objects Plays a necessary role Characterized by attributes Uniquely identifiable (?) Roles Events Places A data object is a domain element that will be manipulated by the system. Characteristics:Examples: External entities Structures Other things Object: car Attributes: VIN # Make Model Price Modeling

5. CpSc 372 Relationships, Cardinality, Modality Cardinality  Defines the number of items on either end of a connection Relationships  Define connections between objects Modality  Defines the necessity of a connection Person Car ownsinsured 11 ** Trailer attached 1 1 Entity-Relationship Diagram (ERD)

6. CpSc 372 DFD: A Basic Example SafeHome software SafeHome software Control panel Control panel Sensors Panel display Panel display Alarm Telephone line Telephone line commands and data sensor status display information telephone tones alarm type External entities (squares) Data flows (directed edges) Processes (circles) Notice that the system is represented as a single bubble. This is known as a level 0 DFD, or a context diagram. (See Pressman Chapter 8, Section 8.6.1, pg. 195)

7. CpSc 372 DFDs and Progressive Refinement Each DFD reveals progressively more detail than the DFD that preceded it. Level 1 DFD: (See Pressman Chapter 8, Section 8.6.1, pg. 196) Interact with user Interact with user Control panel Control panel commands and data Configure system Configure system Configure request Activate / deactivate system Activate / deactivate system Start/stop request Process password Process password … … … Refinement continues until each bubble can be (easily) implemented as a program module.

8. CpSc 372 Process Narrative Process password Process password … … A process specification describes all of the flow processes in the final (most detailed) DFD. A process specification can be represented as a collection of process narratives. “The process password transform performs password validation at the control panel for the SafeHome security function. Process password receives a four-digit password from the interact with user function. The password is first compared to the master password stored within the system …” (See Pressman Chapter 8, Section 8.6.4, pg. 200)

9. CpSc 372 How are DFDs Constructed? Grammatical parse Develop process narratives Level 0 DFD Scope document Grammatical parse Next level DFD (See Pressman Chapter 8, Section 8.6.1, pg. 195) (nouns = external entities, data/control objects, data stores) (verbs = processes) Note that nouns and verbs are associated with one another.

10. CpSc 372 Some Guidelines Level 0 DFD should contain only a single bubble All arrows and bubbles should be meaningfully labeled Refinement begins by isolating next level processes, data objects, and data stores Refine only one bubble at a time Data flow continuity must be maintained between levels

11. CpSc 372 Let’s Try it Out! The video library management system will interact with the user through a web-based browser interface. When the user logs into the system, the system will determine the user’s access privileges based on the user configuration database. If the user is an administrator, the system will allow the user to enter new movie titles, new actor information, etc. If the user is not an administrator, the system will allow the user to query the system based on movie title, actor, director, etc. The Video Library Management System What might the level 0 DFD look like? Level 1? An excerpt from the scope document:

12. CpSc 372 And a Bit of Review The system will allow the user to store a number of information elements with each video, director, and actor. Each video will be characterized by a title, a genre descriptor, a short synopsis, a list of directors, a list of actors, a rating, and a UPC code. Each actor and director will be characterized by a first and last name, a year of birth, and a brief biography. When the user is viewing a video entry, they will be able to retrieve the full actor (or director) information by clicking the actor’s (or director’s) name. Another excerpt from the scope document: What would be an appropriate ERD diagram for this excerpt?