meljun corts system analysis design lecture
TRANSCRIPT
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SYSTEMS ANALYSIS AND DESIGN
MELJUN CORTES
SAD
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Definition
Systems Design
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Definition
Systems design is simple the design ofsystems. It implies a systematic and rigorousapproach to design -- an approach demandedby the scale and complexity of many systemproblems.
Is the third of the five stages of SystemsDevelopment Life Cycle (SDLC).
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Definition
To develop a logical model of the system andconsidered various development strategies.
To create a blueprint that will satisfy alldocumented requirements for the system. Atthis stage, the user interface will be designedand all the necessary outputs, inputs, andprocesses will be identified.
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Definition
Flowchart
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Definition
A flow chart is a graphical or symbolicrepresentation -- This diagrammaticrepresentation can give a step-by-stepsolution to a given problem -- of a process,showing the steps as boxes of various kinds,and their order by connecting these with
arrows.
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Definition
Flowcharts are used in analyzing, designing,documenting or managing a process orprogram in various fields.
Each step in the process is represented by adifferent symbol and contains a shortdescription of the process step. All processesshould flow from top to bottom and left toright.
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Symbols
Flowchart
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Start and End symbol
Represented as circles,
ovals or rounded
rectangles, usually
containing the word"Start" or "End", or
another phrase
signaling the start orend of a process, such
as "submit enquiry" or
"receive product".
Start
End
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Arrow Symbol
Showing "flow of
control".
An arrow coming from
one symbol and ending
at another symbol
represents that control
passes to the symbolthe arrow points to.
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Generic Processing Symbol
Represented as
rectangles.
Denotes the process to
be carried out
Examples: "Add 1 to X";
"replace identified
part"; "save changes"or similar.
Add 1 to X
Save changes
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Input/Output Symbol
Represented as a
parallelogram.
Denotes an input
operation or output
operation.
Examples: Get X from
the user; display X. Display X
Get X
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Conditional or Decision Symbol
Represented as a diamondshowing where a decisionis necessary, commonly aYes/No question or
True/False test. The conditional symbol is
peculiar in that it has twoarrows coming out of it,
usually from the bottompoint and right point, onecorresponding to Yes orTrue, No or False.
Is x =>
10?
Yes
No
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Labeled connectors
Represented by an
identifying label inside
a circle.
Labeled connectors areused in complex or
multi-sheet diagrams
to substitute forarrows.
A
A
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Types
Flowchart
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Types
Document flowcharts
Showing controls over a document-flow through asystem
Data flowcharts
Showing controls over a data flows in a system
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Types
System flowcharts
Showing controls at a physical or resource level
Program flowchart
Showing the controls in a program within asystem
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Types
High-Level Flowchart
A high-level (also called first-level or top-down)flowchart shows the major steps in a process.
It illustrates a "birds-eye view" of a process.
It can also include the intermediate outputs of
each step (the product or service produced), andthe sub-steps involved.
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Types
Detailed Flowchart
The detailed flowchart provides a detailed pictureof a process by mapping all of the steps andactivities that occur in the process.
This type of flowchart indicates the steps or
activities of a process and includes such things asdecision points, waiting periods, tasks thatfrequently must be redone (rework), and feedbackloops.
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Types
Deployment or Matrix Flowchart
A deployment flowchart maps out the process interms of who is doing the steps.
It is in the form of a matrix, showing the variousparticipants and the flow of steps among theseparticipants.
It is chiefly useful in identifying who is providinginputs or services to whom, as well as areas wheredifferent people may be needlessly doing thesame task.
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Introduction
Data Flow Diagram
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Definition
Data Flow Diagram (DFD) is a graphicalrepresentation of the "flow" of data throughan information system, modelingits processaspects.
DFDs can also be used for the visualization
of data processing (structured design).
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Definition
Often they are a preliminary step used tocreate an overview of the system which canlater be elaborated.
A DFD shows what kinds of data will be inputto and output from the system, where the
data will come from and go to, and where thedata will be stored.
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Definition
It does not show information about thetiming of processes, or information aboutwhether processes will operate in sequenceor in parallel.
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Symbols
Data Flow Diagram
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Symbols
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Introduction
Context Diagram
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Definition
In software engineering and systemsengineering, a Context Diagram is a diagramthat represents the actors outside a systemthat could interact with that system.
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Definition
A context diagram is a data flow diagram,with only one massive central process thatsubsumes everything inside the scope of thesystem.
It shows how the system will receive and send
data flows to the external entities involved.
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Definition
Context Diagram is the highest level view of asystem.
Context Diagrams shows a system, oftensoftware-based, as a whole and its inputs andoutputs from/to external factors.
It is similar to a Block diagram.
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Introduction
Gantt Chart
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Definition
A Gantt chart is a graphical representation of theduration of tasks against the progression oftime.
A Gantt chart is a useful tool for planning andscheduling projects.
Gantt charts illustrate the start and finish datesof the terminal elements and summary elementsof a project.
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Definition
Terminal elements and summary elementscomprise the work breakdown structure of theproject.
Some Gantt charts also show the dependencyrelationships between activities.
A Gantt chart is a horizontal bar chart developedas a production control tool in 1917 by Henry L.Gantt, an American engineer and social scientist.
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