module 1.2a diagraming data flows - context diagram.pptx

8/20/2019 Module 1.2a Diagraming Data Flows - Context Diagram.pptx

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Diagramming Data

Module 1.2A:

The Context Diagram


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System Documentation

All the graphical and written

communication that describes theinputs, processing, and data fow

through an Accounting Inormation

System.


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Types of Graphical SystemDocumentation

• Data Flow Diagrams• Traces the data rom input

through specic processes to naldestination.

• Document fowcharts• Traces the fow o documents and

inormation through an IS.

• System fowcharts•

Describes the inormation anddecisions undertaken in a process.

• Program fowcharts• Describes the logical operations in

a computer as it eecutes a

program.


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Diagramming Data

A visual , step by step,representation of the data

owing through the system. • Standard symols capture inputs!

processes and outputs.•

"ines #oin the steps to indicate the$o% of documents and&or data.• 'art of the A(S )Accounting (nformation System*

documentation process.


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+hy Document a System,

So that you can locate the data youneed, and, i need be, trace it back

to it!s source or "erication.

#ro"ides diagnostic capability.

$odels possible bottlenecks, deadends or misdirected data.


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-ses for Documentation

• Depicting ho% the system %ors.• Assists in designing controls! diagnosing

prolems! capturing appropriate data.

• Training users.• Designing ne% systems.• Controlling system costs.•

Standardi/ing communication.• Auditing the A(S.• Documenting business processes.

• 'romotes understanding of the organi/ation0sinformation needs


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Data lo% Diagrams )DDs*

Document the fow o data through asystem.

Cash ReceiptsProcess

Source: Ulric J. Gelinas and Richard Dull ccounting !normationSystems "e


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Data lo% Diagram Symolsxternal Agent ntity )data source ordata destination*

Data lo%

or

(nternal Agent ntity )'hysical DD* or Transforming 'rocess )"ogical DD*

Data Stores )ile*


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Data lo% Diagrams )DDs*Document the fow o data through a

system.

xternal Agent ntity

xternal Agent ntity

'rocess

Data Store



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Data lo% Diagrams )DDs*

Document the fow o data through asystem.

Cash ReceiptsProcess



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DDs Are Sets

• "e3el of Detail – Diagrams are identi4ed as

le3els. – Successi3e diagrams are

dra%n to re3eal more processdetails than the pre3ious le3el.

•

T%o 5ie%s – "ogical DDs sho% the steps in

a process.

– 'hysical DDs sho% the

(nternal Agent entities that

%"ery system re&uires se"eral di'erent

D(D diagrams to complete thedocumentation.


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"e3el of Detail


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"e3els of Detail 6ecap• Processes can #e descri#ed as an o$er$iew

or in increasing detail.• %he ultimate o$er$iew is the Conte&t

Diagram.

• 'ach (e$el o a DFD) or a speci*c process)

descri#es the process in greater detail. – (e$el + is more detailed than the Conte&t

Diagram #ut more o an o$er$iew than(e$el ,.

– (e$el , has greater detail than (e$el + #utless detail than (e$el -

• 'ach new le$el in a DFD diagram) taes a#u##le rom the pre$ious le$el and e&plodes

it into more steps or agents.•


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T%o DD 5ie%s7'hysical


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T%o DD 5ie%s7"ogical


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T%o DD 5ie%s886ecap

• DFDs are created in pairs – (ogical DFDs

•Symols represent the data $o%ingthrough the steps in the process.

• 9o internal agents are represented.

–

Physical DFDs• Sym#ols represent the datahandled #y the internal agents.

• /o process steps are

represented.


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%0' C1/%'2% D!GR3

Dra%ing the DD title page


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The Context Diagram• (ndicates the process eing documented.

• Descries the xternal ntities that input the dataand recei3e data from the process.

Manage-

ment

Bank

Employees

Government

Agencies

Human

Resources

Departments

Payroll

Processing

System

Time ar!s

"e# Employee

$orm

Time ar!s

Employee%ange $orm

Payroll

%e&ue

Payment

A!vice

Payroll Report


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Dra%ing Context Diagrams886ecap

1. -se the circle only to identify the process. – A context diagram is lie a title page. 'ro3ide no

process details. "ist no internal agents.

– Do not include any data stores )computers&4les*.

2. Dra% all entities that pro3ide or recei3e data. – 9ot all input and output entities are at the eginning or

end of the process. (nclude all external entities.

. "ael arro%s %ith the name of the data 9;Tacti3ities.

– or example: "ael an arro% %ith

module 1.2a diagraming data flows - context diagram.pptx

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