Systems Analysis and Design

Transcription

1 Systems Analysis and Design Slides adapted from Jeffrey A. Hoffer, University of Dayton Joey F. George, Florida State University Joseph S. Valacich, Washington State University Modern Systems Analysis and Design, Pearson Prentice Hall, 2011 Chapter 2 The Origins of Software

2 System Acquisition: Outsourcing Turning over responsibility of some or all of an organization's information systems applications and operations to an outside firm Reasons to outsource Cost-effective Take advantage of economies of scale Free up internal resources Reduce time to market Increase process efficiencies System development is a non-core activity for the organization 2-2

3 Reasons to Outsourse Cost Functionality Vendor support Viability of vendor Flexibility Documentation Response time Ease of installation 2-3

4 Sources of Software Information Technology Services Firms Packaged Software Producers Enterprisewide Solutions Cloud Computing Open Source Software In-House Development 2-4

5 Sources of Software 2-5

6 Sources of Application Software: Information Technology Services Help companies develop custom information systems for internal use. Develop, host, and run applications for customers. IBM is the leader in software sales for: Web and application servers, Middleware (links various services). Service Orientation is a new emerging interdisciplinary approach for system development 2-6

7 Sources of Application Software: Packaged Software Producers Microsoft is the leader in prepackaged software production. Prepackaged software is off-the-shelf software. Prepackaged software is often a turnkey software not customizable, the producer will only make change when a substantial number of customers ask for it. Prepackaged software will never perfectly match the organizational business needs Can at best meet 70% of needs 2-7

8 Microsoft Project 2-8

9 2-9 Sources of Application Software: Enterprise Solutions Software Enterprise Resource Planning (ERP) systems that integrate individual traditional business functions into modules enabling a single seamless transaction. Support the entire order entry process to shipping to billing to after-the-sale service. SAP AG is the leading vendor of ERP systems (include sales, purchasing, shipping, warehouse management, production planning, project management, etc). Complex systems, quite expensive Organizations must rely on consultants (expensive) and Even change their business processes

10 Cloud Computing The provision of computing resources, including applications, over the Internet, so customers do not have to invest in the computing infrastructure needed to run and maintain the resources Access complex systems without implementing them in-house Payment: per-use or perlicense Google Apps 2-10

11 Sources of Application Software: Open Source Software Freely available including source code Developed by a community of interested people Performs the same functions as commercial software Examples: Linux, mysql, Firefox 2-11

12 Sources of Application Software: In-House Development If sufficient system development expertise with the chosen platform exists in-house, then some or all of the system can be developed by the organization s own staff. Often, there are a variety of sources used, with in-house staff playing a role as well as consultants or ERP vendors. The choice to acquire or build in-house is made at the end of system analysis phase. The choice is determined by requirements, but not by what a supplier has to sell. 2-12

13 Sources of Software Components 2-13

14 Reuse The use of previously written software resources in new applications Primary enabling technologies Object-oriented development Object class encapsulates data and behavior of common organizational entities (e.g. employees) Component-based software development Components can be functional groupings of object classes 2-14

15 Costs and Benefits of Reuse 2-15

16 Approaches to Reuse low Cost and commitment high Ad hoc: individual, unplanned use Facilitated: use informally managed and disseminated by expert guru evangelists Managed: organizationally enforced reuse policies and practices Designed: assets mandated for reuse as they are being designed for specific applications. 2-16

17 Approaches to Reuse 2-17

18 Summary In this chapter you learned about: Outsourcing. Six different sources of software. Reuse and its role in software development. 2-18