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Design stage
Development and Testing Stage
Next three stages after the design stage :
1- creating the system
2- testing the system
3- improving the system
Each time system is
being changed , due to test result , we have to change other things , in other
word , the second and the third stage will be repeated several times , until
the system is completed.
The designed data
structure can be created by :
1- software
language
2- programming language
programmer will create
the program code to solve the problem . nature of the problem determine the
amount of programming required.
Testing strategies
:
The system analyst ,
will be having a test plan , which will consist of :
1- Expected Data :
the test plan will consist of list of test data together , with the expected
result , to be produced by the system .
2- Actual
result : note of the result which the system in fact produced when the
data is used.
TWO
main ways for testing the system :
1- test data :
Test data has three
types :
a- normal data
b-extreme data
c- abnormal data
a-
Normal data is the data that is
acceptable or valid to the system. Also , this is the data , which
shouldn’t produce any error in the system.
b-
Extreme data is
the data used , when a range of data is input.
c-
Abnormal data is
the data that is not acceptable or valid.
d-
2- Live data : which is the data that is being used in existing system . This
type is used because the outputs are already known.
After all that , before
implementing the system , the mistakes must be corrected . but even though ,
the live data shows other differences , so the process that is used to identify
where and when the difference occurred , by using special software which allows
the system to be run one step at a time to show the exact point where the
difference occurred can be clearly seen in a programming code. This whole
process is called Single
Stepping.
Implementation
there are four types of
implementation :
1- Parallel
running
2- Direct changeover
3- Phased implementation
4- Pilot running
1- Parallel running : running the new system while the new system
is still running .
Pros :
a- Workers
can use the system gradually.
b- Any
problems occurred , which cause the system to stop , the existing system is
still present.
Cons :
a- Two
sets of workers must be paid to keep the two systems work.
b- It
takes longer time to fully implement the new system.
2- Direct Changeover - The existing system is replaced by the new one.
The old one is stopped and
can no longer be used.
happens after thorough testing.
pros
:
- low cost because
only one paid worker.
- very quick
implementation of complete system.
cons
-there is one no
backup in case of errors.
- difficult to make
improvements while keeping it running.
3- Phased implementation : Introducing a system part by part. The system
build up new information and makes a final product. (attendance>payroll).
pros :
- if the new system
stopped in one part , other parts keep working.
- workers have time to
get used to the new system.
cons :
- slow compared to
direct changeover.
- if the new system
doesn't work , impossible to go back to the old one.
3- pilot running
- This method is used in big organisations. it is introducing a new system
in one branch of the organization , while other branches keep on using the old
ones .
pros :
- if an
error occurred , all branches keep on working .
- they can learn from
the experience and errors that have been faced in the branch.
cons:
- slow method of
implementation.
Documentation :
documentation is of
the two forms :
1-
Technical documentation : it is produced specifically for the analyst and the programmer ,
it is needed when the system needs further development or upgrading .
it is divided into two
:
* Systems documentation
and Program documentation.
a- Systems
documentation : provide
a detailed overview if the whole system
b- Program
documentation : needs to be
produced for those pieces of program code that have been written.
2- User documentation :
it is produced to help users to operate the new system.
This type of
documentation is actually provided to help the user how to use the system . it
is just like a tutor contains all the guidelines that are needed when the user
face a problem while using the system.
Evaluation
Evaluation measures
how well the original ambitions of the new system (i.e. the logical design laid
down during the analysis phase) have been achieved.
A system is usually evaluated against a set of criteria :
1- Is the system reliable and robust?
2- Does the system do what it was intended to ?
3- Is the system easy to use?
4- Is the new system efficient ?
5- Is the solution Appropriate?
feedback : information about reactions
to a product, a person's performance of a task, etc., used as a basis for
improvement.
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