Information Technology Reference
In-Depth Information
operating under the same condition. Point evaluation assigns
weights to evaluation factors, and each alternative is evalu-
ated in terms of each factor and given a score from 0 to 100.
After the vendor is chosen, contract negotiations can begin.
At the end of the systems design step, the final specifica-
tions are frozen and no changes are allowed so that imple-
mentation can proceed. One of the most important steps in
systems design is to develop a good contract if new computer
facilities are being acquired. A final design report is developed
at the end of the systems design phase.
must be done, and any existing data to be used in the new
system will require conversion to the new format. Hardware
installation is done during the implementation step, as
is testing. Testing includes program (unit) testing, systems
testing, volume testing, integration testing, and acceptance
testing.
Start-up begins with the final tested information system.
When start-up is finished, the system is fully operational.
There are a number of different start-up approaches. Direct
conversion (also called plunge or direct cutover) involves
stopping the old system and starting the new system on a
given date. With the phase-in approach, sometimes called a
piecemeal approach, components of the new system are
slowly phased in while components of the old one are slowly
phased out. When everyone is confident that the new system
is performing as expected, the old system is completely
phased out. Pilot start-up involves running the new system
for one group of users rather than all users. Parallel start-up
involves running both the old and new systems for a period of
time. The output of the new system is compared closely with
the output of the old system, and any differences are recon-
ciled. When users are comfortable that the new system is
working correctly, the old system is eliminated. Many IS ven-
dors ask the user to sign a formal user acceptance document
that releases the IS vendor from liability for problems that
occur after the document is signed.
Principle
The primary emphasis of systems implementation is
to make sure that the right information is delivered to
the right person in the right format at the right time.
The purpose of systems implementation is to install the
system and make everything, including users, ready for its
operation. Systems implementation includes hardware
acquisition, software acquisition or development, user prepa-
ration, hiring and training of personnel, site and data prepa-
ration, installation, testing, start-up, and user acceptance.
Hardware acquisition requires purchasing, leasing, or renting
computer resources from an IS vendor. Hardware is typically
obtained from a computer hardware vendor.
Software can be purchased from vendors or developed
in-house—a decision termed the make-or-buy decision. Vir-
tualization, first introduced in Chapter 3, has had a profound
impact on many aspects of systems implementation. A pur-
chased software package usually has a lower cost, less risk
regarding the features and performance, and easy installa-
tion. The amount of development effort is also less when
software is purchased. Software as a service (SaaS) is becom-
ing a popular way to purchase software capabilities. Devel-
oping software can result in a system that more closely meets
the business needs and has increased flexibility in terms of
customization and changes. Developing software also has
greater potential for providing a competitive advantage.
Increasingly, companies are using service providers to
acquire software, Internet access, and other IS resources.
Cross-platform development and integrated development
environments (IDEs) make software development easier and
more thorough. CASE tools are often used to automate some
of these techniques. Technical and user documentation is
always important in developing in-house software.
Database and telecommunications software development
involves acquiring the necessary databases, networks,
telecommunications, and Internet facilities. Companies have
a wide array of choices, including newer object-oriented
database systems. Virtual databases and database as a ser-
vice (DaaS) are popular ways to acquire database capabilities.
Implementation must address personnel requirements.
User preparation involves readying managers, employees,
and other users for the new system. New IS personnel might
need to be hired, and users must be well trained in the sys-
tem's functions. Preparation of the physical site of the system
Principle
Maintenance and review add to the useful life of a
system but can consume large amounts of resources.
These activities can benefit from the same rigorous
methods and project management techniques applied
to systems development.
Systems operation is the use of a new or modified system.
Systems maintenance involves checking, changing, and
enhancing the system to make it more useful in obtaining user
and organizational goals. Maintenance is critical for the con-
tinued smooth operation of the system. The costs of perform-
ing maintenance can well exceed the original cost of acquiring
the system. Some major causes of maintenance are new
requests from stakeholders and managers, enhancement
requests from users, bugs or errors, technical or hardware
problems, newly added equipment, changes in organizational
structure, and government regulations.
Maintenance can be as simple as a program patch to
correct a small problem to the more complex upgrading of
software with a new release from a vendor. For older pro-
grams, the total cost of maintenance can be greater than the
total cost of development. Increased emphasis on design can
often reduce maintenance costs. Requests for maintenance
should be documented with a request for maintenance form,
a document that formally authorizes modification of pro-
grams. The development team or a specialized maintenance
team can then make approved changes. Maintenance can be
greatly simplified with the object-oriented approach.
