Introduction, Systems Development: LBG

Systems Development: Requirements, Design, Implementation, Testing

Introduction

What is systems development? More importantly, why do we need it? Consider the following quote:

Almost all large systems evolve over an extended period of time, i. e., over many years or even decades of years. A successful computer system changes its environment and this changed environment brings about new requirements on the computer system itself. Only unsuccessful systems, which are obviously never used, will not undergo changes. Evolving requirements are thus not an exception, but the rule. Existing functions have to be modified, and many new functions have to be added over the lifetime of the system. A scalable architecture is open to such changes, and does not limit the extensibility of a system by some predefined upper limit.

Kopetz, Hermann. Real-Time Systems : Design Principles for Distributed Embedded Applications.
Hingham, MA, USA: Kluwer Academic Publishers, 1997. p 36.

It may seem trivial, but we need systems development because our needs change more as we use systems more. Thus all systems--at least the ones that are used--are in a constant state of flux. So systems development is not only for the creation of new systems, but also to keep popular systems--systems that are actually being used--up to date.

Core Concept

Like many things in our natural world, systems development follows a life cycle. The basic life cycle we will follow in this course has several major stages:

Requirements
Design
Implementation (sometimes called development)
Testing

And as we have seen from the course outline, some of those phases are split into two or more phases.

At its core, systems development is a life cycle process: a collection of processes that, while separable, must be coordinated together and executed over time. This is what makes systems development distinct from, say, programming: the former includes a specific set of multiple activities while the latter is merely one process.

Study Guide

Download this unit's study guide for questions about our readings and a vocabulary list:

Lecture Slides

Here are copies of the lecture slides presented during class:

English

Readings

For this introductory section, we have quite a bit of reading. We need to get familiar with several relevant terms. The following table contains a list of those terms and selected web links (each opening into a new browser window) to help us understand their meanings:

Term	Notes	Links
Process	We said earlier that systems development is a life cycle process. This begs the question: what is a process?	Process Science Theory: read the definition of a process. Process White Paper: read the paragraphs in the "Introducing a Process" section.
Systems Analysis	Analysis is one part of the development life cycle. It is also the most crucial.	What is Systems Analysis: Chapter 1 of Martin Modell's on-line book, "A Professional's Guide to Systems Analysis"
Job Description	We can learn what is expected from a systems analyst by viewing a job description.	Employment Announcement: Texas Department of Housing.
Business Analysis	A related term, business analysis is similar to systems analysis except it considers the business as a whole, and not just an information technology system. However many of the techniques are the same.	Business Analysis: Wikipedia article.
Analysis Life Cycle	The systems analysis life cycle overlaps with development but is more focused on requirements and design then implementation and testing.	The Systems Life Cycle Methodology: Chapter 3 of Modell's on-line book. Systems Development Life Cycle Analysis: (optional) Chapter 4 of Modell's on-line book goes into analysis of the life cycle itself.
Product Life Cycle	Here is an example of another life cycle process. There are many overlaps with systems development.	Product Life Cycle Management: Wikipedia article.
New Product Development	Since we are going to be developing a new product in this course, perhaps we should be aware of another life cycle process.	New Product Development: Wikipedia article.

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