Data flow diagrams (DFDs) are used to model systems by showing how data inputs are transformed through processes into output results. DFDs consist of four main components: entities that are external sources or destinations of data, processes that manipulate data, data stores that hold data between processes, and data flows that show the movement of data between components. DFDs use simple symbols and syntax to represent these components and how they interact in a clear, easy to understand way for both technical and non-technical audiences.
Design Flow Diagram for Information Systemarifasyrafcp13
The document discusses data flow diagrams (DFDs), including their purpose and elements. DFDs model the flow of information through a system using four elements: processes, external entities, data stores, and data flows. They provide a graphical representation of a system that is accessible to both technical and non-technical users. DFDs can diagram current or proposed systems and facilitate analysis, design, and communication with users. Different levels of DFDs exist, with context diagrams providing an overview and Level 0/1 diagrams showing more detailed views of the system. Guidelines help ensure DFDs are constructed correctly.
The document discusses process modeling and data flow diagrams (DFDs). It defines process modeling as a technique used to organize and document a system's processes and flow of data through those processes. DFDs are introduced as a type of process model that depict the flow of data through a system using various symbols like processes, data stores, external entities, and data flows. The document outlines the benefits of process modeling and DFDs, provides examples, and describes the basic components, guidelines, and steps for creating DFDs, including drawing a context diagram and decomposing it into level-0 and level-1 DFDs.
This document provides an overview of data flow diagrams (DFDs) and context diagrams. It discusses what DFDs are used for, including communicating requirements to stakeholders and analyzing existing and proposed systems. The key elements of DFDs are described as external entities, processes, data stores, and data flows. Context diagrams show the major information flows between external entities and the system at a high level. Lower level DFDs then decompose the processes into more detail.
- Data flow diagrams (DFDs) graphically describe the flow of data within an organization using four basic elements: data sources and destinations, data flows, transformation processes, and data stores. DFDs are subdivided into lower levels to provide more detail. The highest-level DFD is called the context diagram.
- Flowcharts are used to describe business processes and document flows using standard symbols divided into four categories: input/output, processing, storage, and miscellaneous. Types of flowcharts include program, system, document, and internal control flowcharts.
- Business process diagrams visually describe the steps in a business process.
Data flow diagrams (DFDs) provide a graphical representation of how data moves through a system. DFDs use four main symbols: processes, data stores, external entities, and data flows. They allow system analysts and users to depict and understand the flow of data in a system. DFDs come in two main types: context diagrams provide an overview of the system and its interactions, while level 0 DFDs show more detail about the system's major sub-processes, data stores, and flows at a high level. Together, DFDs enable customers and users to specify requirements by modeling the system's data flows.
This chapter discusses data and process modeling tools used during systems analysis, including data flow diagrams (DFDs), a data dictionary, and process descriptions. DFDs use symbols like processes, data flows, data stores, and entities to graphically represent how data moves through a system. A data dictionary centrally documents all data elements, data flows, processes, and other system components. Process descriptions explain the business logic and processing steps using structured tools like structured English, decision tables, and decision trees. The end goal of modeling is a logical model that shows what the system does at a high level without details of how it is implemented physically.
The document discusses system analysis and recording information. It describes the PARIS model for system analysis, which includes planning, asking questions, recording information, interpreting information, and specifying requirements. It also discusses using data flow diagrams and entity models to record information about current and required systems, including the components of DFDs and how they are used to hierarchically represent a system. Entity models represent relationships between types of data.
Data flow diagrams (DFDs) are used to model systems by showing how data inputs are transformed through processes into output results. DFDs consist of four main components: entities that are external sources or destinations of data, processes that manipulate data, data stores that hold data between processes, and data flows that show the movement of data between components. DFDs use simple symbols and syntax to represent these components and how they interact in a clear, easy to understand way for both technical and non-technical audiences.
Design Flow Diagram for Information Systemarifasyrafcp13
The document discusses data flow diagrams (DFDs), including their purpose and elements. DFDs model the flow of information through a system using four elements: processes, external entities, data stores, and data flows. They provide a graphical representation of a system that is accessible to both technical and non-technical users. DFDs can diagram current or proposed systems and facilitate analysis, design, and communication with users. Different levels of DFDs exist, with context diagrams providing an overview and Level 0/1 diagrams showing more detailed views of the system. Guidelines help ensure DFDs are constructed correctly.
The document discusses process modeling and data flow diagrams (DFDs). It defines process modeling as a technique used to organize and document a system's processes and flow of data through those processes. DFDs are introduced as a type of process model that depict the flow of data through a system using various symbols like processes, data stores, external entities, and data flows. The document outlines the benefits of process modeling and DFDs, provides examples, and describes the basic components, guidelines, and steps for creating DFDs, including drawing a context diagram and decomposing it into level-0 and level-1 DFDs.
This document provides an overview of data flow diagrams (DFDs) and context diagrams. It discusses what DFDs are used for, including communicating requirements to stakeholders and analyzing existing and proposed systems. The key elements of DFDs are described as external entities, processes, data stores, and data flows. Context diagrams show the major information flows between external entities and the system at a high level. Lower level DFDs then decompose the processes into more detail.
- Data flow diagrams (DFDs) graphically describe the flow of data within an organization using four basic elements: data sources and destinations, data flows, transformation processes, and data stores. DFDs are subdivided into lower levels to provide more detail. The highest-level DFD is called the context diagram.
- Flowcharts are used to describe business processes and document flows using standard symbols divided into four categories: input/output, processing, storage, and miscellaneous. Types of flowcharts include program, system, document, and internal control flowcharts.
- Business process diagrams visually describe the steps in a business process.
Data flow diagrams (DFDs) provide a graphical representation of how data moves through a system. DFDs use four main symbols: processes, data stores, external entities, and data flows. They allow system analysts and users to depict and understand the flow of data in a system. DFDs come in two main types: context diagrams provide an overview of the system and its interactions, while level 0 DFDs show more detail about the system's major sub-processes, data stores, and flows at a high level. Together, DFDs enable customers and users to specify requirements by modeling the system's data flows.
This chapter discusses data and process modeling tools used during systems analysis, including data flow diagrams (DFDs), a data dictionary, and process descriptions. DFDs use symbols like processes, data flows, data stores, and entities to graphically represent how data moves through a system. A data dictionary centrally documents all data elements, data flows, processes, and other system components. Process descriptions explain the business logic and processing steps using structured tools like structured English, decision tables, and decision trees. The end goal of modeling is a logical model that shows what the system does at a high level without details of how it is implemented physically.
The document discusses system analysis and recording information. It describes the PARIS model for system analysis, which includes planning, asking questions, recording information, interpreting information, and specifying requirements. It also discusses using data flow diagrams and entity models to record information about current and required systems, including the components of DFDs and how they are used to hierarchically represent a system. Entity models represent relationships between types of data.
A Data Flow Diagram (DFD) visually represents the flow of information within a system using symbols like circles, arrows, and parallel lines. It shows how data enters and leaves the system as well as where data is stored. DFDs are broken into levels that depict increasing functional detail, starting with a context-level diagram representing the entire system as one process and external entities, then breaking the system into sub-processes at lower levels. Key elements are uniquely named and DFDs avoid logical decisions or excessive detail to clearly depict data flows.
System analysis and design involves analyzing business processes and requirements and designing logical systems models. Key activities include fact finding, modeling current and required systems, and producing requirements specifications and logical models. Data flow diagrams (DFDs) are a common modeling technique, depicting the flow of data through a system via processes, external entities, and data stores. DFDs are drawn at different levels of detail, with level 0 providing an overview and higher levels showing more granular decompositions of processes. Proper notation, numbering, labeling, and balancing are important for effective DFDs.
Data flow diagrams (DFDs) are a visual way to represent how data moves through a system or process. DFDs show the four major components of a system - entities, processes, data stores, and data flows. Entities are sources or destinations of data outside the system boundary. Processes perform functions to transform data. Data stores hold data between processes. Data flows represent the movement of data between components. DFDs are hierarchical, with a high-level overview in a Level 0 diagram drilled down into more detail in lower-level diagrams. DFDs help analysts, designers and others understand how a current or planned system will work at a glance.
Chapter08 structuring system requirementsDhani Ahmad
This document discusses process modeling and data flow diagrams (DFDs). It covers the basics of DFDs including the symbols used, rules for creating them, decomposition, and balancing DFDs. Four types of DFDs are described: current physical, current logical, new logical, and new physical. The document also discusses using DFDs as analysis tools, for business process reengineering, compares DFDs to Oracle's Process Modeler and functional hierarchy diagrams.
SE2018_Lec 14_ Process Modeling and Data Flow Diagram.pptxAmr E. Mohamed
The document discusses process modeling and data flow diagrams (DFDs). It begins by defining a system as consisting of inputs, outputs, and a process within defined boundaries. Logical and physical models are then described, with logical models showing what a system does independent of implementation and physical models including implementation details. The remainder of the document provides details on:
- Creating DFDs using processes, external entities, data stores, and data flows
- Developing context and level-0 diagrams
- Decomposing processes through functional decomposition and creating level-N diagrams
- Ensuring DFDs are complete and consistent
Data Flow Diagrams (DFDs) are graphical tools used in software engineering to visualize how data moves through a system. A DFD shows the flow of data between external entities and processes, as well as data storage components. It uses standard symbols like rectangles, circles, and arrows. DFDs are hierarchical, with multiple levels showing increasing detail. A 0-level DFD provides an overview of the entire system as a single bubble, while 1-level and 2-level DFDs decompose this into subprocesses and further detail. Key aspects like inputs, outputs, processes, and data storage are represented. DFDs do not show control flow or logic.
Data flow diagrams (DFDs) graphically represent the flow of data through processes in a system without focusing on computational steps. DFDs use four main symbols: processes, data stores, external entities, and data flows. DFDs can be partitioned into multiple levels that show increasing detail from the overall context level down. Control specifications complement DFDs by specifying how the system behaves in response to events using state transition diagrams and process activation tables.
The document discusses rules and guidelines for creating data flow diagrams (DFDs). It explains the key components of DFDs including external entities, data stores, data flows, and processes. It provides rules for how these components can and cannot be connected and used. It also discusses creating context diagrams, level-0 diagrams, and decomposing DFDs into lower levels through a balancing process.
This document provides an overview of data flow diagrams (DFDs), including their introduction, components, notation, levels, examples, and advantages/disadvantages. DFDs were introduced to graphically represent data flow in business systems. They model processes, external entities, data storage, and data flows. The document outlines rules for creating DFDs and defines the components and notation used to represent different elements. It also describes the different levels of DFDs from overall system view to process-level detail. Examples of clothing and food ordering systems are given. Advantages include understanding system functioning and limits, while disadvantages are potential for confusion and time required.
This chapter discusses the importance of documenting accounting information systems. It covers various documentation tools used such as flowcharts, process maps, data flow diagrams, and decision tables. It provides guidelines for creating different types of flowcharts and discusses other documentation tools. It also talks about documenting end-user computing and how documentation is important for training, system development and auditing.
A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system, modeling its process aspects.
Why DFD technique is so Popular?
Symbols used in DFD
Constructing DFD Models
Data Dictionary
Developing the DFD model of System
Level O DFD or Context Diagram
Level 1 DFD
Strengths of DFD Model
Weaknesses of DFD Model
This document provides an overview of data flow diagrams (DFDs) and how they can be used to model system processes and requirements. It discusses how DFDs visually represent the flow of data between external entities, processes, and data stores. DFDs can be decomposed into multiple levels that show both high-level and low-level views of the system. The document also describes guidelines for drawing DFDs, such as using consistent notation and stopping decomposition at the primitive level. Finally, it discusses how DFDs can be used as analysis tools to identify gaps and inefficiencies in systems.
SSAD is an integrated set of standards and guidelines for analyzing and designing computer systems. It includes tools like data flow diagrams, data dictionaries, decision trees, structured English, and decision tables. Some key techniques of SSAD include data flow modeling, logical data structures, and entity life histories. SSAD provides benefits like improved productivity, flexibility, quality and on-time delivery, while also ensuring user needs are met. However, it also has disadvantages like large costs and time requirements for training and its document standards.
Here we uploaded E workshop system design with complete details. This details helpful for students who are freshers. Even software developers can refer this document. For project source code visit www.studentprojectguide.com
Data flow diagrams (DFDs) are used to model systems and show how input data is transformed into output through a series of functional steps. DFDs reveal relationships between different components in a program or system. They have four main elements - entities, processes, data stores, and data flows. Entities represent external sources or recipients of data, processes perform functions to transform data, data stores hold data between processes, and data flows show the movement of data between elements.
This document provides an overview of data flow diagrams (DFDs), including their components, development process, and purposes. It describes DFDs as a technique for modeling system requirements and information flows. Key points:
- DFDs have four main components - processes, data stores, external entities, and data flows. They are developed at different levels of detail, starting with a high-level context diagram then more detailed lower levels.
- The development process involves gathering requirements, drawing a document flow diagram to define the system boundary, then creating DFDs showing information flows and processes within and outside the system.
- DFDs are used to discuss system processes with users, determine what the new system should
Need for System Analysis
Stages in System Analysis
Structured SAD and tools :
DFD
Context Diagram
Decision Table
Structured Diagram.
System Development Models:
Water Flow
Prototype
Spiral
RAD
Roles and responsibilities of
System Analyst,
Database Administrator
Database Designer
This document discusses data flow diagrams (DFDs) and their use in structuring system process requirements. It provides an overview of DFDs and describes how they can be used to model processes, decompose diagrams into lower levels, and balance high-level and low-level views. The document also discusses the four types of DFDs (current physical, current logical, new physical, new logical), and guidelines for drawing DFDs, including rules for decomposition, stopping decomposition, and using DFDs for analysis.
System Architecture and Development PRESENTATIONaaravSingh41
The document provides an overview of data flow diagrams and entity relationship diagrams. It defines what a DFD is, its components and symbols. It also explains what an ERD is and how to create one, including defining entities, attributes, relationships and cardinality. Examples of a DFD and ERD are given to illustrate the concepts.
This document provides an overview of data flow diagrams (DFDs):
1. DFDs visually represent how information moves through a system and can be used to document current systems or plan new ones. They have four main components: external entities, processes, data stores, and data flows.
2. Multiple levels of DFDs can be created, starting with a high-level context diagram and drilling down into more detail in lower levels. Categories include physical and logical DFDs.
3. An example process of developing DFDs is outlined, starting with gathering requirements and creating a document flow diagram before building the initial context and level 1 DFDs and then more detailed lower levels.
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A Data Flow Diagram (DFD) visually represents the flow of information within a system using symbols like circles, arrows, and parallel lines. It shows how data enters and leaves the system as well as where data is stored. DFDs are broken into levels that depict increasing functional detail, starting with a context-level diagram representing the entire system as one process and external entities, then breaking the system into sub-processes at lower levels. Key elements are uniquely named and DFDs avoid logical decisions or excessive detail to clearly depict data flows.
System analysis and design involves analyzing business processes and requirements and designing logical systems models. Key activities include fact finding, modeling current and required systems, and producing requirements specifications and logical models. Data flow diagrams (DFDs) are a common modeling technique, depicting the flow of data through a system via processes, external entities, and data stores. DFDs are drawn at different levels of detail, with level 0 providing an overview and higher levels showing more granular decompositions of processes. Proper notation, numbering, labeling, and balancing are important for effective DFDs.
Data flow diagrams (DFDs) are a visual way to represent how data moves through a system or process. DFDs show the four major components of a system - entities, processes, data stores, and data flows. Entities are sources or destinations of data outside the system boundary. Processes perform functions to transform data. Data stores hold data between processes. Data flows represent the movement of data between components. DFDs are hierarchical, with a high-level overview in a Level 0 diagram drilled down into more detail in lower-level diagrams. DFDs help analysts, designers and others understand how a current or planned system will work at a glance.
Chapter08 structuring system requirementsDhani Ahmad
This document discusses process modeling and data flow diagrams (DFDs). It covers the basics of DFDs including the symbols used, rules for creating them, decomposition, and balancing DFDs. Four types of DFDs are described: current physical, current logical, new logical, and new physical. The document also discusses using DFDs as analysis tools, for business process reengineering, compares DFDs to Oracle's Process Modeler and functional hierarchy diagrams.
SE2018_Lec 14_ Process Modeling and Data Flow Diagram.pptxAmr E. Mohamed
The document discusses process modeling and data flow diagrams (DFDs). It begins by defining a system as consisting of inputs, outputs, and a process within defined boundaries. Logical and physical models are then described, with logical models showing what a system does independent of implementation and physical models including implementation details. The remainder of the document provides details on:
- Creating DFDs using processes, external entities, data stores, and data flows
- Developing context and level-0 diagrams
- Decomposing processes through functional decomposition and creating level-N diagrams
- Ensuring DFDs are complete and consistent
Data Flow Diagrams (DFDs) are graphical tools used in software engineering to visualize how data moves through a system. A DFD shows the flow of data between external entities and processes, as well as data storage components. It uses standard symbols like rectangles, circles, and arrows. DFDs are hierarchical, with multiple levels showing increasing detail. A 0-level DFD provides an overview of the entire system as a single bubble, while 1-level and 2-level DFDs decompose this into subprocesses and further detail. Key aspects like inputs, outputs, processes, and data storage are represented. DFDs do not show control flow or logic.
Data flow diagrams (DFDs) graphically represent the flow of data through processes in a system without focusing on computational steps. DFDs use four main symbols: processes, data stores, external entities, and data flows. DFDs can be partitioned into multiple levels that show increasing detail from the overall context level down. Control specifications complement DFDs by specifying how the system behaves in response to events using state transition diagrams and process activation tables.
The document discusses rules and guidelines for creating data flow diagrams (DFDs). It explains the key components of DFDs including external entities, data stores, data flows, and processes. It provides rules for how these components can and cannot be connected and used. It also discusses creating context diagrams, level-0 diagrams, and decomposing DFDs into lower levels through a balancing process.
This document provides an overview of data flow diagrams (DFDs), including their introduction, components, notation, levels, examples, and advantages/disadvantages. DFDs were introduced to graphically represent data flow in business systems. They model processes, external entities, data storage, and data flows. The document outlines rules for creating DFDs and defines the components and notation used to represent different elements. It also describes the different levels of DFDs from overall system view to process-level detail. Examples of clothing and food ordering systems are given. Advantages include understanding system functioning and limits, while disadvantages are potential for confusion and time required.
This chapter discusses the importance of documenting accounting information systems. It covers various documentation tools used such as flowcharts, process maps, data flow diagrams, and decision tables. It provides guidelines for creating different types of flowcharts and discusses other documentation tools. It also talks about documenting end-user computing and how documentation is important for training, system development and auditing.
A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system, modeling its process aspects.
Why DFD technique is so Popular?
Symbols used in DFD
Constructing DFD Models
Data Dictionary
Developing the DFD model of System
Level O DFD or Context Diagram
Level 1 DFD
Strengths of DFD Model
Weaknesses of DFD Model
This document provides an overview of data flow diagrams (DFDs) and how they can be used to model system processes and requirements. It discusses how DFDs visually represent the flow of data between external entities, processes, and data stores. DFDs can be decomposed into multiple levels that show both high-level and low-level views of the system. The document also describes guidelines for drawing DFDs, such as using consistent notation and stopping decomposition at the primitive level. Finally, it discusses how DFDs can be used as analysis tools to identify gaps and inefficiencies in systems.
SSAD is an integrated set of standards and guidelines for analyzing and designing computer systems. It includes tools like data flow diagrams, data dictionaries, decision trees, structured English, and decision tables. Some key techniques of SSAD include data flow modeling, logical data structures, and entity life histories. SSAD provides benefits like improved productivity, flexibility, quality and on-time delivery, while also ensuring user needs are met. However, it also has disadvantages like large costs and time requirements for training and its document standards.
Here we uploaded E workshop system design with complete details. This details helpful for students who are freshers. Even software developers can refer this document. For project source code visit www.studentprojectguide.com
Data flow diagrams (DFDs) are used to model systems and show how input data is transformed into output through a series of functional steps. DFDs reveal relationships between different components in a program or system. They have four main elements - entities, processes, data stores, and data flows. Entities represent external sources or recipients of data, processes perform functions to transform data, data stores hold data between processes, and data flows show the movement of data between elements.
This document provides an overview of data flow diagrams (DFDs), including their components, development process, and purposes. It describes DFDs as a technique for modeling system requirements and information flows. Key points:
- DFDs have four main components - processes, data stores, external entities, and data flows. They are developed at different levels of detail, starting with a high-level context diagram then more detailed lower levels.
- The development process involves gathering requirements, drawing a document flow diagram to define the system boundary, then creating DFDs showing information flows and processes within and outside the system.
- DFDs are used to discuss system processes with users, determine what the new system should
Need for System Analysis
Stages in System Analysis
Structured SAD and tools :
DFD
Context Diagram
Decision Table
Structured Diagram.
System Development Models:
Water Flow
Prototype
Spiral
RAD
Roles and responsibilities of
System Analyst,
Database Administrator
Database Designer
This document discusses data flow diagrams (DFDs) and their use in structuring system process requirements. It provides an overview of DFDs and describes how they can be used to model processes, decompose diagrams into lower levels, and balance high-level and low-level views. The document also discusses the four types of DFDs (current physical, current logical, new physical, new logical), and guidelines for drawing DFDs, including rules for decomposition, stopping decomposition, and using DFDs for analysis.
System Architecture and Development PRESENTATIONaaravSingh41
The document provides an overview of data flow diagrams and entity relationship diagrams. It defines what a DFD is, its components and symbols. It also explains what an ERD is and how to create one, including defining entities, attributes, relationships and cardinality. Examples of a DFD and ERD are given to illustrate the concepts.
This document provides an overview of data flow diagrams (DFDs):
1. DFDs visually represent how information moves through a system and can be used to document current systems or plan new ones. They have four main components: external entities, processes, data stores, and data flows.
2. Multiple levels of DFDs can be created, starting with a high-level context diagram and drilling down into more detail in lower levels. Categories include physical and logical DFDs.
3. An example process of developing DFDs is outlined, starting with gathering requirements and creating a document flow diagram before building the initial context and level 1 DFDs and then more detailed lower levels.
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2. Avicenna
System Analysis and Design
System Analysis 2
Learning Objectives
Describe data flow diagrams
Describe the symbols used in data
flow diagrams and explain the
rules for their use
3. Avicenna
System Analysis and Design
System Analysis 3
Process model
Process model
A formal way of representing how a business
system operates
Illustrates the activities that are performed
and how data moves among them
4. Avicenna
System Analysis and Design
System Analysis 4
Data Flow Diagrams
Data Flow Diagrams - Introduction
Data flow diagrams can be used to provide a
clear representation of any business function.
The technique starts with an overall picture of
the business and continues by analyzing each of
the functional areas of interest. This analysis
technique can be carried out to precisely the
level of detail required. The technique exploits a
method called top-down expansion to conduct
the analysis in a targeted way.
5. Avicenna
System Analysis and Design
System Analysis 5
Data Flow Diagrams
Graphical representation of a system’s data and how the processes
transform the data, is known as Data Flow Diagram (or DFD)
DFD is one of the most important tools in a structured system
analysis. It presents a method of establishing relationship between
functions or processes of the system with information it uses.
DFD is a key component of the system requirement specification,
because it determines what information is needed for the process
before it is implemented
Data flow diagrams are the most commonly used way of
documenting the process of current & required systems.
A data flow diagram (DFD) shows how data moves through an
information system but does not show program logic or processing
steps
A set of DFDs provides a logical model that shows what the system
does, not how it does it
6. Avicenna
System Analysis and Design
System Analysis 6
Data Flow Diagrams
Data flow diagram supports 4 main activities:
Analysis: DFD used to determine requirements of users
Design: DFD used to map out plan and illustrate solutions to
analysts and users while designing a new system
Communication: DFD is simple and easy to understand to
analysts and users
Documents: DFD used to provide special description of
requirements and system design. DFD provide an overview of
key functional components of the system but it does not
provide any detail on these components.
7. Avicenna
System Analysis and Design
System Analysis 7
Data Flow Diagrams
DFD Symbols
DFDs use four basic symbols that represent
processes, data flows, data stores, and
entities
Symbols are referenced by using all capital
letters for the symbol name
Components of DF Diagrams
Processes change data
Data flows between processes
External entities interact from outside
Data stores hold data internally
8. Avicenna
System Analysis and Design
System Analysis 8
Data Flow Diagrams
Two different standard sets can be used
DeMarco and Yourdan
Gane and Sarson
Data flow diagram symbols, symbol names, and examples for the
Gane and Sarson and Yourdon symbol sets. [1]
9. Avicenna
System Analysis and Design
System Analysis 9
Data Flow Diagrams
Process symbol
Receives input data and produces output that has a different
content, form, or both
Contain the business logic which determines how a system
handles data and produces useful information. Business
logic, also called business rules, reflect the operational
requirements of the business.
Process name identifies a specific function and consists of
verb, and an adjective, if necessary
a process symbol can be referred to as a black box, because
the inputs, outputs, and general functions of the process are
known, but the underlying details and logic of the process
are hidden
10. Avicenna
System Analysis and Design
System Analysis 10
Data Flow Diagrams
DFD Symbols
Data flow symbol
A data flow is a path for data to move from one part
of the information system to anther
Represents one or more data items
The detailed content of the data flow does not appear in the
DFD
The symbol for a data flow is a line with a single or double
arrowhead
A data flow name consists of a singular noun and an
adjective, if needed
Is detailed in the data dictionary
11. Avicenna
System Analysis and Design
System Analysis 11
Data Flow Diagrams
At least one data flow must enter and one data
flow must exit each process symbol
Examples of correct combinations of data flow and process symbols. [1]
12. Avicenna
System Analysis and Design
System Analysis 12
Data Flow Diagrams
Examples of incorrect
combinations of data
flow and process
symbols.
APPLY INSURANCE
PREMIUM has no input
and is called a
spontaneous generation
process.
CALCULATE GROSS PAY
has no outputs and is
called a black hole
process.
CALCULATE GRADE has
an input that is
obviously unable to
produce the output.
This process is called
a gray hole.
[1]
13. Avicenna
System Analysis and Design
System Analysis 13
Data Flow Diagrams
DFD Symbols
Data store symbol
Represent data that the system stores
A DFD does not show the detailed content of data store
The physical characteristics of a data store are unimportant
because you are concerned only with a logical model
Is a flat rectangle that is open on the right side and closed
on the left side
A data store name is a plural name consisting of a noun and
adjectives, if needed
can be duplicated, one or more times, to avoid line crossing.
is detailed in the data dictionary
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Data Flow Diagrams
A data store must be connected to process with a data flow
A data store must have at least one incoming and one outgoing data flow
One exception when data store has no input data flow because it contains
fixed reference data that is not updated by the system
Examples of correct uses of data store symbols in a data flow diagram. [1]
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Data Flow Diagrams
Examples of incorrect uses of data store symbols: two
data stores cannot be connected by a data flow without
an intervening process, and each data store should have
an outgoing and incoming data flow. [1]
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Data Flow Diagrams
DFD Symbols
Entity Symbol
Symbol is a rectangle, which may be shaded to make it look three-
dimensional
An entity name is the singular form of a department, outside organization,
other information system, or person
Name of the entity appears inside the symbol
A DFD shows only the external entities that provide data to the system or
receive output from the system
can be duplicated, one or more times, on the diagram to avoid line crossing.
determine the system boundary. They are external to the system being
studied. They are often beyond the area of influence of the developer.
go on margins/edges of data flow diagram
Entities also called
Terminators: because they are data origins or final destination
Source: for entity that supplies data to the system
Sink: for entity that receives data from the system
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Data Flow Diagrams
Entity can be connected with a process only
Examples of correct uses of external entities in a data flow diagram.[1]
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Data Flow Diagrams
Examples of incorrect uses of external entities. An
external entity must be connected by a data flow to a
process, and not directly to a data store or to another
external entity. [1]
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Data Flow Diagrams
Rules for connecting processes, data
stores, and entities in a DFD. [1]
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Sequence Summary
During data and process modeling, a systems analyst
develops graphical models to show how the system
transforms data into useful information
Data flow diagrams (DFDs) graphically show the
movement and transformation of data in the information
system
DFDs use four symbols: the process symbol transforms
data; the data flow symbol shows data movement; the
data store symbol shows data at rest; and the external
entity symbol represents someone or something
connected to the information system
Various rules and techniques are used to name,
number, arrange, and annotate the set of DFDs to
make them consistent and understandable
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Sequence Summary
In this Sequence we have
Described data flow diagrams
Explained the activates DFD supports
Described the symbols used in data flow
diagrams includes: process, data flow,
external entities, and data stores
Explain the rules for data flow diagram
symbols and their use
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Reference
[1] System Analysis and Design, Sixth Edition
Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt ,
Publisher: SHELLY CASHMAN SEWIES.
[2] system analysis and design, sixth edition
Authors: Kenneth E. Kendall and Julie E. Kendall
Publisher: Prentice Hall
[3] Modern Systems Analysis and Design Third Edition
Authors: Jeffrey A. Hoffer , Joey F. George, Joseph S. Valacich
Publisher: prentice hall
[4] System Analysis and Design, 3rd Edition
Authors: Dennis, Wixom, & Roth
Publisher: John Wiley & sons
