Download - The Systems Life Cycle: Analysis 2
![Page 1: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/1.jpg)
The Systems Life Cycle: Analysis 2
Data flow & information requirements
![Page 2: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/2.jpg)
Objectives:
Establishing IPSO Recording information about the
existing system Identifying the problems with the
system Identifying User & Information
requirements of the new system Identifying HW & SW for a new
system.
![Page 3: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/3.jpg)
So far….
Our analyst has collected information about the current system using questionnaires, observation, interviews and examining documents.
What happens next?
![Page 4: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/4.jpg)
Step 2: Need to identify all the
inputs, processing & outputs in the existing system.
How?
![Page 5: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/5.jpg)
1: Examination of documents
This allows the analyst to establish which documents relate to information coming IN to the system, and which relate to information going OUT.
![Page 6: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/6.jpg)
What happens to this information?
The analyst uses this knowledge to produce his own documentation of the system which helps him understand the system properly.
![Page 7: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/7.jpg)
Each section…
….needs to be examined to see the specific inputs, processes & outputs.
What would be the inputs of a payroll system?
The processes? The outputs?
![Page 8: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/8.jpg)
2 : Recording information about the current system All results of fact-finding
must be recorded Accurate records are
vital – why? Because the system will
evolve Other analysts &
programmers will need to develop the system even further at some point in the future.
![Page 9: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/9.jpg)
How do we record the flow of data?
Data flow diagrams These are a graphical
method of recording the inputs, processing & outputs that have been identified.
![Page 10: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/10.jpg)
Flow charts vs DFDs
Flow charts show the control flow of the program
DFDs show how the data flows around the entire system
![Page 11: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/11.jpg)
3 : DFDS….
Data flow diagrams illustrate how data is processed by a system in terms of inputs and outputs.
Have four components: Terminators Processes Flow arrows Stores
![Page 12: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/12.jpg)
An example
Process
order
Customers
Orders
Rejected Orders
Orders
Invoices Invoic
e data
Order In
formati
on
![Page 13: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/13.jpg)
An explanation
Customers A Terminator - someone or something outside the system (eg a customer or a supplier)
Invoices Data stores – where stored on paper or on a computer
Data flow. It is important that the direction of the flow is accurately recorded.
Process
orderProcess order
![Page 14: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/14.jpg)
Different levels of DFDs
Level 0 Very generalised Shows terminators linked
to current system eg 0Customers
Order Processing system
Customers
![Page 15: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/15.jpg)
Different levels of DFDs
Level 1: Many more processes More detail Process boxes for both
receiving orders and for producing invoices 1
![Page 16: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/16.jpg)
Different levels of DFDs
Level 2: These show all aprts of
the level 1 diagram in much more detail 2
![Page 17: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/17.jpg)
DFDs:
Represent the way that data flows around the existing (old) system
![Page 18: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/18.jpg)
System flowcharts
May be used, but generally are found in the design stage.
Represent the new system – the one that is going to be designed & implemented.
![Page 19: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/19.jpg)
4 : Identifying problems with the current system DFDs help the analyst to
identify problems or weaknesses within the current system: Eg data duplication Job duplication Unnecessary steps
Why is it necessary to identify these problems?
![Page 20: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/20.jpg)
5 : Identifying suitable hardware & software for the new system
DFDs help the analyst decide on: Appropriate methods of
input Approximate processor
speed & memory Size & number of
storage devices Quantity & format of
output
![Page 21: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/21.jpg)
6: Identifying the user & information requirements The new system MUST meet the
needs of the people who will use it So – the analyst needs to know
exactly what job each person does and what their requirements are.
He can the produce a Requirements Specification – a list of features of the system that are required.
![Page 22: The Systems Life Cycle: Analysis 2](https://reader035.vdocuments.site/reader035/viewer/2022062810/56815d54550346895dcb5dd8/html5/thumbnails/22.jpg)
Analysis Summary
Step 1 : collecting information on how the current system works
Step 2 : Establishing inputs, processes & outputs
Step 3 : recording information Step 4 : Identifying problems Step 5 : Identifying suitable hardware &
software Step 6 : Identifying user & information
requirements