Information Systems Development
Introduction
When someone has an idea for a new function to be performed by a
computer, how does that idea become reality? If a company wants to
implement a new business process and needs new hardware or software
to support it, how do they go about making it happen? In this reading, we
will discuss the different methods of taking those ideas and bringing them
to reality, a process known as information systems development.
Programming
As we learned in Software, it is created via programming. Programming is
the process of creating a set of logical instructions for a digital device to
follow using a programming language. The process of programming is
sometimes called coding because the syntax of a programming language
is not in a form that everyone can understand—it is in “code.”
The process of developing good software is usually not as simple as
sitting down and writing some code. True, sometimes a programmer can
quickly write a short program to solve a need. But most of the time, the
creation of software is a resource‐intensive process that involves several
different groups of people in an organization. In the following sections,
we are going to review several different methodologies for software
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development.
Systems‐Development Life Cycle
The development methodology, systems‐development life cycle (SDLC),
was first developed in the 1960s to manage the large software projects
associated with corporate systems running on mainframes. It is a very
structured and risk‐averse methodology designed to manage large
projects that included multiple programmers and systems that would have
a large impact on the organization.
Various definitions of the SDLC methodology exist, but most contain the
following phases.
1. Preliminary Analysis. In this phase, a review is done of the request. Is
creating a solution possible? What alternatives exist? What is
currently being done about it? Is this project a good fit for our
organization? A key part of this step is a feasibility analysis, which
includes an analysis of the technical feasibility (Is it possible to create
this?), the economic feasibility (Can we afford to do this?), and the
legal feasibility (Are we allowed to do this?). This step is important in
determining if the project should even get started.
2. System Analysis. In this phase, one or more system analysts work
with different stakeholder groups to determine the specific
requirements for the new system. No programming is done in this
step. Instead, procedures are documented, key players are
interviewed, and data requirements are developed in order to get an
overall picture of exactly what the system is supposed to do. The
result of this phase is a system‐requirements document.
3. System Design. In this phase, a designer takes the system‐
requirements document created in the previous phase and develops
the specific technical details required for the system. It is in this
phase that the business requirements are translated into specific
technical requirements. The design for the user interface, database,
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data inputs and outputs, and reporting are developed here. The
result of this phase is a system‐design document. This document will
have everything a programmer will need to actually create the
system.
4. Programming. The code finally gets written in the programming
phase. Using the system‐design document as a guide, a programmer
(or team of programmers) develop the program. The result of this
phase is an initial working program that meets the requirements laid
out in the system‐analysis phase and the design developed in the
system‐design phase.
5. Testing. In the testing phase, the software program developed in the
previous phase is put through a series of structured tests. The first is
a unit test, which tests individual parts of the code for errors or bugs.
Next is a system test, where the different components of the system
are tested to ensure that they work together properly. Finally, the
user‐acceptance test allows those that will be using the software to
test the system to ensure that it meets their standards. Any bugs,
errors, or problems found during testing are addressed and then
tested again.
6. Implementation. Once the new system is developed and tested, it
has to be implemented in the organization. This phase includes
training the users, providing documentation, and conversion from
any previous system to the new system. Implementation can take
many forms, depending on the type of system, the number and type
of users, and how urgent it is that the system become operational.
These different forms of implementation are covered later in this
reading.
7. Maintenance. This final phase takes place once the implementation
phase is complete. In this phase, the system has a structured support
process in place: reported bugs are fixed and requests for new
features are evaluated and implemented; system updates and
backups are performed on a regular basis.
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SDLC Waterfall
Seven phases of the systems‐
development life cycle methodology
The SDLC methodology is sometimes referred to as the waterfall
methodology to represent how each step is a separate part of the
process; only when one step is completed can another step begin. After
each step, an organization must decide whether to move to the next step
or not. This methodology has been criticized for being quite rigid. For
example, changes to the requirements are not allowed once the process
has begun. No software is available until after the programming phase.
Again, SDLC was developed for large, structured projects. Projects using
SDLC can sometimes take months or years to complete. Because of its
inflexibility and the availability of new programming techniques and tools,
many other software‐development methodologies have been developed.
Many of these retain some of the underlying concepts of SDLC, but are
not as rigid.
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The RAD Methodology
Rapid application development
methodology
Public Domain
Rapid application development (RAD) is a software‐development (or
systems‐development) methodology that focuses on quickly building a
working model of the software, getting feedback from users, and then
using that feedback to update the working model. After several iterations
of development, a final version is developed and implemented.
The RAD methodology consists of four phases:
1. Requirements Planning. This phase is similar to the preliminary‐
analysis, system‐analysis, and design phases of the SDLC. In this
phase, the overall requirements for the system are defined, a team is
identified, and feasibility is determined.
2. User Design. In this phase, representatives of the users work with
the system analysts, designers, and programmers to interactively
create the design of the system. One technique for working with all
of these various stakeholders is the so‐called JAD session. JAD is an
acronym for joint application development. A JAD session gets all of
the stakeholders together to have a structured discussion about the
design of the system. Application developers also sit in on this
meeting and observe, trying to understand the essence of the
requirements.
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