MELJUN CORTESSAD

DefinitionSystems Design

DefinitionSystems design is simple the design of systems. It implies a systematic and rigorous approach to design -- an approach demanded by the scale and complexity of many system problems. Is the third of the five stages of Systems Development Life Cycle (SDLC).

DefinitionTo develop a logical model of the system and considered various development strategies.

To create a blueprint that will satisfy all documented requirements for the system. At this stage, the user interface will be designed and all the necessary outputs, inputs, and processes will be identified.

DefinitionFlowchart

DefinitionA flow chart is a graphical or symbolic representation -- This diagrammatic representation can give a step-by-step solution to a given problem -- of a process, showing the steps as boxes of various kinds, and their order by connecting these with arrows.

DefinitionFlowcharts are used in analyzing, designing, documenting or managing a process or program in various fields.

Each step in the process is represented by a different symbol and contains a short description of the process step. All processes should flow from top to bottom and left to right.

SymbolsFlowchart

Start and End symbolRepresented as circles, ovals or rounded rectangles, usually containing the word "Start" or "End", or another phrase signaling the start or end of a process, such as "submit enquiry" or "receive product".

Arrow SymbolShowing "flow of control". An arrow coming from one symbol and ending at another symbol represents that control passes to the symbol the arrow points to.

Generic Processing SymbolRepresented as rectangles. Denotes the process to be carried outExamples: "Add 1 to X"; "replace identified part"; "save changes" or similar.

Input/Output SymbolRepresented as a parallelogram. Denotes an input operation or output operation.Examples: Get X from the user; display X.

Conditional or Decision SymbolRepresented as a diamond showing where a decision is necessary, commonly a Yes/No question or True/False test. The conditional symbol is peculiar in that it has two arrows coming out of it, usually from the bottom point and right point, one corresponding to Yes or True, No or False.

Labeled connectorsRepresented by an identifying label inside a circle. Labeled connectors are used in complex or multi-sheet diagrams to substitute for arrows.

TypesFlowchart

TypesDocument flowchartsShowing controls over a document-flow through a system

Data flowchartsShowing controls over a data flows in a system

TypesSystem flowcharts Showing controls at a physical or resource level

Program flowchartShowing the controls in a program within a system

TypesHigh-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), and the sub-steps involved.

TypesDetailed Flowchart

The detailed flowchart provides a detailed picture of a process by mapping all of the steps and activities that occur in the process.This type of flowchart indicates the steps or activities of a process and includes such things as decision points, waiting periods, tasks that frequently must be redone (rework), and feedback loops.

TypesDeployment or Matrix Flowchart

A deployment flowchart maps out the process in terms of who is doing the steps. It is in the form of a matrix, showing the various participants and the flow of steps among these participants. It is chiefly useful in identifying who is providing inputs or services to whom, as well as areas where different people may be needlessly doing the same task.

IntroductionData Flow Diagram

DefinitionData Flow Diagram (DFD) is a graphical representation of the "flow" of data through aninformation system, modeling itsprocessaspects.

DFDs can also be used for the visualization ofdata processing(structured design).

DefinitionOften they are a preliminary step used to create an overview of the system which can later be elaborated.

A DFD shows what kinds of data will be input to and output from the system, where the data will come from and go to, and where the data will be stored.

DefinitionIt does not show information about the timing of processes, or information about whether processes will operate in sequence or in parallel.

SymbolsData Flow Diagram

Symbols

IntroductionContext Diagram

DefinitionIn software engineering and systems engineering, a Context Diagram is a diagram that represents the actors outside a system that could interact with that system.

DefinitionA context diagram is a data flow diagram, with only one massive central process that subsumes everything inside the scope of the system.

It shows how the system will receive and send data flows to the external entities involved.

DefinitionContext Diagram is the highest level view of a system.

Context Diagrams shows a system, often software-based, as a whole and its inputs and outputs from/to external factors.

It is similar to a Block diagram.

IntroductionGantt Chart

DefinitionA Gantt chart is a graphical representation of the duration of tasks against the progression of time.

A Gantt chart is a useful tool for planning and scheduling projects.

Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project.

DefinitionTerminal elements and summary elements comprise the work breakdown structure of the project.

Some Gantt charts also show the dependency relationships between activities.

A Gantt chart is a horizontal bar chart developed as a production control tool in 1917 by Henry L. Gantt, an American engineer and social scientist.