Peter works as a Database Administrator for UnrealTech Inc. Management instructs him to create a
schema that is gradually expanded from
one level to another through appropriate modifications. Which of the following approaches will he
use to accomplish the task?
A.
Top down approach
B.
Bottom up approach
C.
Mixed approach
D.
Inside-out approach
Explanation:
In a top-down approach, a schema is created through a series of successive refinements, starting
from the first schema, which is gradually
expanded by using appropriate modifications that increase the detail of the various concepts.
Moving from one level to another, the schema is
modified using some basic transformations called top-down transformation primitives.
Answer B is incorrect. In a bottom-up approach, the preliminary specifications are broken down into
smaller components so that each
component describes a basic fragment of the specifications. These components are then
represented by schemas, some of which may consist
of single concepts. The schemas are later obtained to be integrated together until a final schema is
obtained.
Answer D is incorrect. Inside-out approach can be regarded as a particular type of bottom-up
approach. It begins with the identification
of only a few important concepts and, based on these, the design proceeds, spreading outward
‘radially’. First the concepts nearest to theinitial concepts are represented, and a user then moves towards those further away by means of
‘navigation’ through the specification.
Answer C is incorrect. In a mixed approach, the designer decomposes the requirements into a
number of components, as in the
bottom-up approach, but not to the extent where all the concepts are separated. At the same time,
a skeleton schema is defined containing
the main concepts of the application. This skeleton schema gives a unified view of the whole design
and helps the integration of schemas
developed separately. Then the designer examines separately these main concepts and can proceed
with gradual refinements following the
top-down approach or extending a portion with concepts that are not yet represented following the
bottom-up approach.
In a bottom-up approach, the preliminary specifications are broken down into
smaller components so that each
component describes a basic fragment of the specifications. These components are then
represented by schemas, some of which may consist
of single concepts. The schemas are later obtained to be integrated together until a final schema is
obtained.
Answer D is incorrect. Inside-out approach can be regarded as a particular type of bottom-up
approach. It begins with the identification
of only a few important concepts and, based on these, the design proceeds, spreading outward
‘radially’
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