Database Reference
In-Depth Information
Are there unique fields in the input, so that each record can be distinguished from all other
records?
When is the data input, how often, and in what volume?
Processing Requirements
To determine an information system
'
s processing requirements, you need to find answers to the following
types of questions:
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Which input data must be retained as stored data to provide the required outputs?
What calculations must be performed?
Are there special cycle processing requirements that occur daily, weekly, monthly, quarterly,
annually, or on some other frequency? For example, are there requirements for weekly or biweekly
payroll processing, quarterly and annual tax processing, and quarterly shareholder processing?
Are there auditing requirements for the data in the information system?
Which stored data has special security requirements that permit only authorized users access or
update privileges?
Are there procedures that depend on other procedures?
Are there procedures that occur in a specified sequence?
Which procedures and other processing requirements are available to all end users, and which
ones are limited to only authorized personnel?
Technical and Constraining Requirements
To determine an information system
'
s technical and constraining requirements, you need to find answers to
the following types of questions:
Must the information system operate with a specific operating system or with multiple operating
systems?
Which DBMS will be used to store retained data?
Does the hardware
—
entry, storage, output, and other devices
—
impose any restrictions or
provide special capabilities?
Which programming languages will be used for creating the application programs for the
information system?
How many end users must the information system support concurrently, and what response time
is expected for online processing?
Which portions of the information system must be available to end users 24/7?
DETERMINING SYSTEM REQUIREMENTS
Many tools and methods have been developed to help you analyze and document system requirements after
you
ve determined what they are, but no similar aids exist to help you determine them in the first place.
To determine system requirements, you need to become a detective and collect the facts about the
information system using basic fact-finding techniques. The most commonly used techniques for determining
the facts about an information system are interviews, document collection, observation, and research.
'
Interviews
An interview is a planned meeting during which you obtain system requirements from other people. You
conduct these interviews with the individuals who represent the people component of the information
system, each of whom has a personal perspective about what the information system should do. You conduct
individual and group interviews, during which you determine how the information system operates now, how
it should operate in the future, and what requirements need to be in the new information system.
In large organizations with hundreds of end users and other people who have system requirements,
especially when they work in a large number of locations, you can
t conduct interviews with everybody.
In these situations, you can use surveys and questionnaires to allow everybody to participate and to obtain
their system requirements.
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