meljun corts system analysis design lecture

8/13/2019 MELJUN CORTS System Analysis Design Lecture

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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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meljun corts system analysis design lecture

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