Building a GIS Application
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BUILDING A GIS Application
a)Waterfall method
1. Gathering requirements and specifications
2. Designing
3. Implementation
4. Testing
5. Adaptation
Requirement analysis and specifications involve interaction among sponsors, users and developers
of the software product. The purpose of requirement analysis is to produce a requirement document
clearly specifying the agreed upon goals and the functionality of the proposed product as well as
the constraint under which it will be operating.
Design involves the generation of a design document to serve as a blue print for the proposed
system. Developers and adaptors are usually involved in this process. Adaptors are involved in
order to help assure that the design is consistent with a graceful evolution of the system. The design
document often includes graphical depictions of system structure as well as textual material which
documents the preconditions and postconditions of all functions.
Implementation involves building the system described in the design document. This includes
making important decisions about data structures and algorithms as well as writing the program
code itself. These decisions can have significant impact upon the efficiency of the system.
Testing involves detecting as many defects in the software system as possible. Unit testing seeks to
find defects in individual software components (such as functions) while integration testing seeks
to find defects which might arise when assembled components fail to work correctly in concert
with one another.
Adaptation (maintenance) refers to the evolution of the completed system.
The software lifecycle model in practice is not perfectly sequential. There are loops which
feedback from later stages to earlier ones in the cycle. For example the discovery of an error during
integration testing could force the developer to go back to the implementation or the design stage.
It has been shown that the earlier an error is found in the lifecycle the less costly it is to correct. It
is thus less expensive to correct an error discovered during the design stage than it is to fix an error
discovered during the testing or adaptation stages.
Over the life of a typical system, the adaptation stage is by the most expensive. In this case analysis
and specification are considered together.
A major disadvantage of the software cycle model is that sponsors and users of the system do not
get to see a working model of the system until near the end of the development process.
b)Prototyping
Prototyping is the process of building a model of a system. In terms of Computer system,
prototypes are employed to help system designers build an information system that is intuitive and
easy to manipulate for end users. Prototyping is an iterative process that is part of the analysis
phase of the systems development life cycle.
During this analysis phase, prototyping usually referred to as the discovery prototypes are very
important because it is geared for understanding the users’ needs. The prototypes are not built for
full functionality but are built to see if the prototypes are feasible for the goals the business is
trying to achieve.
BUILDING A GIS Application
a)Waterfall method
1. Gathering requirements and specifications
2. Designing
3. Implementation
4. Testing
5. Adaptation
Requirement analysis and specifications involve interaction among sponsors, users and developers
of the software product. The purpose of requirement analysis is to produce a requirement document
clearly specifying the agreed upon goals and the functionality of the proposed product as well as
the constraint under which it will be operating.
Design involves the generation of a design document to serve as a blue print for the proposed
system. Developers and adaptors are usually involved in this process. Adaptors are involved in
order to help assure that the design is consistent with a graceful evolution of the system. The design
document often includes graphical depictions of system structure as well as textual material which
documents the preconditions and postconditions of all functions.
Implementation involves building the system described in the design document. This includes
making important decisions about data structures and algorithms as well as writing the program
code itself. These decisions can have significant impact upon the efficiency of the system.
Testing involves detecting as many defects in the software system as possible. Unit testing seeks to
find defects in individual software components (such as functions) while integration testing seeks
to find defects which might arise when assembled components fail to work correctly in concert
with one another.
Adaptation (maintenance) refers to the evolution of the completed system.
The software lifecycle model in practice is not perfectly sequential. There are loops which
feedback from later stages to earlier ones in the cycle. For example the discovery of an error during
integration testing could force the developer to go back to the implementation or the design stage.
It has been shown that the earlier an error is found in the lifecycle the less costly it is to correct. It
is thus less expensive to correct an error discovered during the design stage than it is to fix an error
discovered during the testing or adaptation stages.
Over the life of a typical system, the adaptation stage is by the most expensive. In this case analysis
and specification are considered together.
A major disadvantage of the software cycle model is that sponsors and users of the system do not
get to see a working model of the system until near the end of the development process.
b)Prototyping
Prototyping is the process of building a model of a system. In terms of Computer system,
prototypes are employed to help system designers build an information system that is intuitive and
easy to manipulate for end users. Prototyping is an iterative process that is part of the analysis
phase of the systems development life cycle.
During this analysis phase, prototyping usually referred to as the discovery prototypes are very
important because it is geared for understanding the users’ needs. The prototypes are not built for
full functionality but are built to see if the prototypes are feasible for the goals the business is
trying to achieve.
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