INFORMATION SYSTEM IMPLEMENTATION AND MAINTENANCE
Information Systems Life Cycle can be divided into three broad categories.
IMPLEMENTATION AND MAINTENANCE
The remaining steps in
the systems development process translate the solution specifications
established during systems analysis and design into a fully operational information
system. These concluding steps consist of programming, testing, conversion, and
production and maintenance.
1. Programming
The process of
translating design specifications into software for the computer constitutes a
smaller portion of the systems development cycle than design and perhaps the
testing activities. But it here, in providing the actual instructions for the machine,
that the heart of the system takes shape. During the programming stage, system
specifications that were prepared during the design stage are translated into program
code. On the basis of detailed design documents for files, transaction and report
layouts, and other design details, specifications for each program in the
system are prepared.
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Some systems development
projects assign programming tasks to specialists whose work consists
exclusively of coding programs. Other projects prefer programmer/ analysts who
both design and program functions. Since large systems entail many programs
with thousands – even hundreds of thousands – of lines of code, programming
teams are frequently used. Moreover, even if an entire system can be programmed
by a single individual, the quality of the software will be higher if it is subject
to group review.
2.
Testing
Exhaustive and thorough
testing must be conducted to ascertain whether the system produces the right
results. Testing answers the question, “Will the system produce the desired
results under known conditions?”
The amount of time needed
to answer this question has been traditionally underrated in systems project
planning. As much as 50 per cent of the entire software development budget can
be extended in testing. Testing is also time-consuming: Test data must be
carefully prepared, results reviewed, and corrections made in the system. In
some instances, parts of the system may have to be redesigned. Yet the risks of
glossing over this step are enormous.
Testing information
system can be broken down into three types of activities: Unit testing, or
program testing, consists of testing each program separately in the system.
While it is widely believed that the purpose of such testing each program
separately in antee that programs is error free, this goal is realistically
impossible. Testing should be viewed instead as a means of locating errors in
programs, focusing on finding all the ways to make a program fail. Once
pinpointed, problems can be corrected.
System testing the functioning of the information system as a whole. It tries
to determine if discrete modules will function together as planned and whether discrepancies
exist between the ways the system actually works and the way it was conceived.
Among the areas examined are performance times, capacity for the storage and
handling peak loads, recovery and restart capabilities, and manual procedures.
Acceptance testing provides the final certification that the system is ready to be
used in a production setting. Systems tests are evaluated by users and reviewed
by management. When all parties are satisfied that the new system meets their standards,
the system is formally accepted for installation.
It is essential that all
aspects of testing be carefully thought out and that they be as comprehensive
as possible. To ensure this, the development team works with users to devise a
systematic test plan. The test plan includes all of the preparations for the series
of tests previously described.
The general condition
being tested here is a record change. The documentation consists of a series of
test-plan screens maintained on a database (perhaps a microcomputer database)
that is ideally suited to this kind of application.
Users play a critical
role in the testing process. They understand the full range of data and
processing conditions that might occur within their system. Moreover, programmers
tend to be aware only of the conditions treated in their programs; the test
data they devise are usually too limited. Therefore, input from other team members
and users will help ensure that the range of conditions included in the test data
is complete. Users can identify frequent and less common transactions, unusual conditions
to anticipate, and most of the common types of errors that might occur when the
system is in use. User input is also decisive in verifying the manual procedures
for the system.
3. Conversion
Conversion is the process
of changing from the old system to the new system. It answers the question,
“Will the new system work under real conditions?” Four main conversion
strategies can be employed: the parallel strategy, the direct cutover strategy,
the pilot study strategy, and the phased approach strategy.
In a parallel strategy,
both the old system and its potential replacement are run together for a time
until everyone is assured that the new one functions correctly. This is the
safest conversion approach because, in the even to errors or processing disruptions,
the old system can still be used as a backup. However, this approach is very
expensive, and additional staff or resources may be required to run the extra system.
The direct cutover
strategy replaced the old system entirely with the new
system on an appointed day. At first glance, this strategy seems less costly
than parallel conversion strategy. However, it is a very risky approach that
can potentially be more costly than parallel activities if serious problems
with the new system are found. There is no other system to fall back on.
Dislocations, disruptions, and the cost of corrections may be enormous.
The pilot study strategy introduces the new system only to a limited area of the organization,
such as a single department or operating unit. When this pilot version is complete
and working smoothly, it is installed throughout the rest of the organization, either
simultaneously or in stages.
The phased approach
strategy introduces the new system in stages, either
by functions or by organizational units. If, for example, the system is
introduced by functions, a new payroll system might begin with hourly workers
who are paid weekly, followed six months later by adding salaried employees who
are paid monthly to the system. If the system is introduced by organizational
units, corporate headquarters might be converted first, followed by outlaying
operating units four months later.
A formal conversion plan
provides a schedule of all the activities required to install the new system.
The most time-consuming activity is usually the conversion of data. Data from
the old system must be transferred to the new system, either manually or through
special conversion software programs. The converted data then must be carefully
verified for accuracy and completeness.
Moving from an old system
to a new one requires that end users be trained to use the new system. Detailed
documentation showing how the system works from both a technical and end-user
standpoint is finalized during conversion time for use in training and everyday
operations. Lack of proper training and documentation contributes to system
failure, so this portion of the systems development process is very important.
4. Production and Maintenance
After the new system is
installed and conversion is complete, the system is said to be in production.
During this stage, both users and technical specialists to determine how well
it has met its original objectives and to decide whether any revisions or modifications
are in order will review the system. Changes in hardware, software, documentation,
or improve processing efficiency are termed maintenance.
Studies of maintenance
have examined the amount of time required for various maintenance tasks.
Approximately 20 per cent of the 20 per cent is concerned with changes in data,
files, reports, hardware, or system software. But 60 percent of all maintenance
work consists of making user enhancements, improving documentation, and
recording system components for greater processing efficiency. The amount of work
in the third category of maintenance problems could be reduced significantly through
better system analysis and design practices.
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