Systems Analysis and Design Alan Dennis and Barbara

Systems Analysis and Design Alan Dennis and Barbara Haley Wixom John Wiley & Sons, Inc. Slides by Fred Niederman Slide 1 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Copyright © 2000 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in Section 117 of the 1976 United States Copyright Act without the express written permission of the copyright owner is unlawful. Request for further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for redistribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages, caused by the use of these programs or from the use of the information contained herein. 2 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

System Design Chapter 8 Slide 3 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Key Definitions The purpose of the design phase is to translate the “what” of the analysis phase to the “how” of new system development In this phase decisions are made regarding hardware and software, system architecture, user interface structure and components, object persistence and class method design. --Slide modified by the instructor 02/25/02 4 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Object Oriented Analysis and Design Planning Requirements Gathering & Use Case Development Build: Analysis Design Implementation Library Patterns Iteration System 1 Build: Analysis Design Implementation Library Patterns Iteration System 2 Build: Analysis Design Implementation Library Patterns Iteration System 3 First the use cases with the highest priority In the following we will only address the next step – Design. Slide created by the instructor 02/25/02 5 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Evolving the Analysis Models int Design Models The purpose of the analysis models was to represent the underlying business problem domain as a set of collaborating objects. The purpose of design models is to increase the likelihood of successfully deliver a system that implements the system that the analysis models describe. Slide created by the instructor 02/25/02 6 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Methods Factoring is the process of identifying new classes or methods extracting from the existing classes and methods in order to create new ones. Abstraction is the process of creating a higher level idea from a set of ideas. Refinement is the process of identifying subclasses Slide created by the instructor 02/25/02 7 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Partitions and Collaborations Partitioning means dividing the system into subsystems or partitions. Partitions are often found by looking into collaboration diagrams. Slide created by the instructor 02/25/02 8 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Layers One layer per element of the system domain E. g. , foundation, system architecture, human-computer interaction, data management, problem domain See figure 9 -3 page 250 for examples. Slide created by the instructor 02/25/02 9 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Layers -- Examples Foundation – fundamental data types (integers, real numbers, characters, strings, trees, graphs) System Architecture – how software executes on specific computers and networks (interaction with middleware such as CORBA or MS DCOM) – more in Chapter 10 Human computer interaction – windows, text fields, scroll bars, check boxes etc. – more in Chapters 11 and 12 Data Management – persistence of objects – choice of storage format (relational, object data bases) – more in Chapter 13 Problem Domain – our primary focus until now – more in Chapter 13 Slide created by the instructor 02/25/02 10 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Packages and Clusters Package is a general construct that can be applied to any element in UML models. Package diagram is a class diagram that shows packages only. Packages can participate in different types of relationships. See figure 9 -4 on page 252. For five steps to create packages see figure 97 on page 255. Slide created by the instructor 02/25/02 11 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Design Strategies Custom development (build from scratch) Purchase and customize Outsource development 12 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Design Strategies Slide 13 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Custom Development Pros Cons Allows flexibility and creativity Requires significant time and effort Builds technical skills and functional knowledge in-house May exacerbate existing backlogs May require missing skills Often costs more Often takes more calendar time Risk of project failure 14 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Packaged Software Include small single-function tools All-encompassing enterprise resource planning (ERP) systems Rarely a perfect fit with business needs May allow for customization Manipulation of system parameters Changing way features work Synchronizing with other application interfaces 15 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Systems Integration Building systems by combining packages, legacy systems, and custom pieces Integrating data is the key 16 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Outsourcing Hiring an external vendor, developer, or service provider May reduce costs or add value Risks include possibly Losing confidential information Losing control over future development Losing learning opportunities 17 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Outsourcing Contracts Time and arrangements Fixed-price Value-added 18 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Outsourcing Guidelines Keep lines of communication open Define and stabilize requirements before signing the contract View the relationship as a partnership Select vendor, developer, or provider carefully Assign someone to manage the relationship Don’t outsource what you don’t understand Emphasize flexible requirements 19 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Selecting a Design Strategy Consider each of the following: Business need In-house experience Project skills Project management Time frame 20 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Developing The Actual Design Slide 21 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Developing an Alternative Matrix What tools and technologies are needed for a custom development project? What vendors make products that address the project needs? What service providers would be able to build this application if outsourced? 22 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Requests for Proposals (RFP) Solicits proposals from vendor, developer, or service providers Explains the system and criteria for selecting among applicants Request for Information (RFI) -- a shorter version 23 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.

Request for Proposal Contents Description of desired system Special technical needs or circumstances Evaluation criteria Instructions on how to respond Desired schedule Other information that will help the submitter to make a more complete or accurate proposal 24 Power. Point Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved.