IS 341
Business Systems Analysis
Chapter 1 - Notes
I. What Is Systems Analysis and Design? Basically, it is the process of developing
and maintaining an information system.
System a group of interrelated elements
working together to accomplish a specific goal or task
Analysis a study of the CURRENT
system, a look backward at what already exists
Design moving forward to something
new; putting together all the elements identified in the analysis process to
create a new system
A.
It is done for a PURPOSE a Business purpose ($$).
B.
The system collects Data from within & without the organization and
uses this data to produce Information that is useful to the organization. The particular Data and Information depend
on:
1. The organizations objectives, structure, and
processes; and
2. How the organization decides to exploit
information technologies for Competitive Advantage.
C.
Success in this endeavor is usually accomplished by following a
Structured approach such as the SDLC.
II. Systems Analysis and Design: Core Concepts
A.
Application Software does a specific job for the user.
B.
Information Systems all of the hardware, software, documentation
controls, and persons (both developers and users) involved in collecting and
processing the data being turned into information in a specific situation.
C.
Organizational approach to SAD a specific combination of three
elements that works well for a particular organization or in a specific setting
(note this is a Business approach, not a Techie approach)
1. Methodology a step-by-step approach to
solving a specific problem
2. Technique processes that you follow to
ensure that your work is well thought-out, complete, and comprehensible to
others.
3. Tools software (e.g., CASE tools) that make
it easier to use specific techniques.
III. Systems
A.
Definition of a System and Its Parts
System a group of
interrelated elements working together to accomplish a specific goal or task; has
nine (9) characteristics
1.
Components irreducible parts or group of parts (subsystems) that makes
up the system
2.
Interrelated dependence of one part on one or more other parts of the
system
3. Boundary
demarcation that separates the system from everything outside the system
4. Purpose
the overall goal or function of the system
5.
Environment everything external to the system with which the systems
does or may interact
6.
Interface point of contact where system meets environment (or where
two subsystems meet)
7.
Constraint a limitation;
Three
basic (most common) constraints: Time,
Finances (Money), People
8. Inputs
9. Outputs
B. Important System
Concepts
1. Decomposition
breaking sown a system into its smaller components
a. smaller parts are easier
to understand and more manageable
b. Focus attention on one
area (subsystem) at a time
c. Focus attention on one
group of users at a time
d. Build different parts of the system at
different times (or different groups building different parts at the same time)
2. Modularity dividing a system into chunks
(modules) of the same size
3. Coupling the extent to which modules depend
on each other; modules should be as lightly coupled (independent) of each other
as possible so that a failure in one will not bring down the other modules
4. Cohesion the extent to which a subsystem
performs a single function; each subsystem should exhibit high cohesion (should
only have a single function)
IV. A Modern Approach to Systems Analysis and
Design
Systems
Integration a major focus today which allows hardware & software from
different vendors to work together in an application
A. Your Role in
Systems Development the primary role of the Systems Analyst is to study the
problems and needs of an organization in order to determine how people,
methods, and information technology can best be combined to bring about
improvements in the organization.
BUSINESS FOCUS!
Systems Analysts in Systems Development
need four (4) skills:
1. Analytical to understand the organization,
and to identify problems and opportunities (systems thinking)
2. Technical understand the potentials and
limitations of technology
3. Managerial manage projects, resources,
risk, and change
4. Interpersonal skills work with all kinds of
people, end users as well as other technicians (programmers and analysts)
NOTE:
Business Process Redesign (BPR)
examining a firms basic processes (how it goes about doing business) with
the idea of improving those processes, discovering better processes, or doing
business in a completely new manner.
3 methodologies of BPR: Restructuring, Reverse Engineering,
Re-Engineering
V. Developing Information Systems and the Systems Development Life Cycle
Systems Development Methodology standard process followed in an organization to conduct all the steps necessary to [plan,] analyze, design, implement, & maintain information systems.
Systems Development Life Cycle
(SDLC) The series of steps used to mark the phases of development for an
information system. A logical process
used (by analysts, etc.) to build information systems/applications to solve
business problems/needs.
A. Phase 1: Systems Planning and Selection the organizations total information (system) needs are analyzed; potential information systems projects are identified to solve those needs; arguments are presented for (not) continuing with the project(s); two (2) primary activities:
1. Identify needs and possible solutions (systems) to those needs; written requests for solutions, and feasibility study for a solution
2. Investigate the proposed system and determine its scope, written plans for solutions, estimates of needed resources to proceed
B. Phase 2: Systems Analysis current systems are studied and alternative systems are proposed
1. Determine requirements of the new system (what do users want?)
2. Study/structure/arrange requirements (full understanding)
3. Generate alternative solutions to match the requirements
C. Phase 3: Systems Design the system chosen in the analysis phase is described independently of any computer platform (logical/conceptual design) and is transformed into technology-specific details (physical design) for future programming and construction
1. Logical/Conceptual Design theoretical, can be implemented on any hardware; focus on the Business aspects/requirements of the system
2. Physical Design break down the logical specifications into smaller and smaller units that can be converted into instructions in a programming language, and applied to specific hardware platforms
D. Phase 4: Systems Implementation and Maintenance [NOT Operation!] the system is coded, tested, installed, then repaired and improved
(NOTE: Operation does _NOT_ belong here! See Phase 5)
E. Phase 5: Systems Operation and Maintenance longest phase, system is utilized by users, maintenance and upgrades are provided as needed
VII. Approaches to Development
A. Prototyping a working model, a scaled-down version of the system;
1. Advantages of Prototyping:
a. It involves the user directly in the development process;
b. It captures requirements in concrete form, rather than abstract/verbal form.
2. Types of Prototypes:
a. Type I a working model thats gets bigger and bigger and eventually becomes the system itself
b. Type II a throw-away model used to demonstrate key elements of the system to users; once it is approved, throw away the prototype then develop the new system in a real programming language
B. Computer-Aided Software Engineering (CASE) Tools automated software tools (programs) used to develop information systems. They automate/support various activities throughout the development process.
1. Repository centralized database that contains absolutely everything about the project
2. Types of CASE tools:
a. Diagramming (Modeling) tools graphically represent data, processes, control structures, etc.
b. Report Generators both display and print reports, speeds prototyping
c. Analysis tools check for incomplete, inconsistent, or incorrect specifications
d. Central Repository enables integrated storage of all parts of the specifications, diagrams, reports, project management information
e. Document Generators produce technical and user documentation
f. Code Generators automatics generation of program and database definition code directly from design documentation
C. Joint Application Design (JAD IBM, early 1970s) structured (FORMAL!) process where users, managers and analysts work together in intensive meetings to specify/structure/review systems requirements (versus Brainstorming); includes Facilitator, Agenda, Time Limits
D. Rapid Application Design (RAD) supported by CASE, Prototyping, and JAD;
Delays producing detailed system design documents until user requirements are clear;
methodology which uses prototypes for very quickly building/rebuilding systems while working closely with users by gaining user acceptance of interfaces and key system capabilities; may overlook key systems development principles by going too quickly & cause problems later (i.e., sacrifices computer efficiency for gains in human efficiency)
E. Participatory Design (PD northern European idea, where labor roles are different from North America) alternative to SDLC focusing on users and improvement of their work-lives; users (or their representatives) make decisions about needs and solutions. Users make the decisions about needs and solutions generally, the systems analysts work for the users (reverses roles of users and management).
F. Agile Methodologies development methodologies with short iterative cycles, extensive testing, and active user involvement; many new ideas on how to shorten delivery time, improve quality, and lower delivery costs (remember the 3 ways your boss always wants a project? See introductory notes)
Three key principles:
1. Focus on adaptive rather than predictive methodologies
2. Focus on People rather than roles
3. As methodologies are applied, they are adapted to a particular need/context