Podcast
Questions and Answers
What is the requirement for a process in a DFD?
What is the requirement for a process in a DFD?
- It must only have inputs.
- It can be represented without any labels.
- It must have both inputs and outputs. (correct)
- It must function without outputs.
What does data flow from a data store to a process signify?
What does data flow from a data store to a process signify?
- Delete data.
- Update existing data.
- Create new data.
- Retrieve or use data. (correct)
Which statement accurately describes the role of external entities in a DFD?
Which statement accurately describes the role of external entities in a DFD?
- They represent internal processes of the system.
- They provide inputs or receive outputs from the system. (correct)
- They only represent data storage mechanisms.
- They are independent from the system and do not interact.
What is the primary role of labels in data flows within a DFD?
What is the primary role of labels in data flows within a DFD?
When should a DFD decomposition be stopped, according to the rules?
When should a DFD decomposition be stopped, according to the rules?
What does 'completeness' refer to in the context of drawing DFDs?
What does 'completeness' refer to in the context of drawing DFDs?
What type of diagram serves as an overview of an entire system?
What type of diagram serves as an overview of an entire system?
What is a significant limitation of DFDs with respect to time representation?
What is a significant limitation of DFDs with respect to time representation?
What do external entities in a Data Flow Diagram represent?
What do external entities in a Data Flow Diagram represent?
In a Level-1 DFD, what is the primary purpose of decomposing processes?
In a Level-1 DFD, what is the primary purpose of decomposing processes?
Which of the following correctly identifies a common labeling convention in DFDs?
Which of the following correctly identifies a common labeling convention in DFDs?
What is indicated by the arrows in a Data Flow Diagram?
What is indicated by the arrows in a Data Flow Diagram?
Which statement best describes the concept of entity independence in DFDs?
Which statement best describes the concept of entity independence in DFDs?
Which sub-process is NOT a part of the Order Processing process within the Online Library System?
Which sub-process is NOT a part of the Order Processing process within the Online Library System?
What is the primary role of the Verify User Credentials sub-process in the Level-2 DFD?
What is the primary role of the Verify User Credentials sub-process in the Level-2 DFD?
What does a Level-n DFD accomplish in the context of system design?
What does a Level-n DFD accomplish in the context of system design?
What role do external entities play in a Data Flow Diagram?
What role do external entities play in a Data Flow Diagram?
Which step is first in the process of creating a Data Flow Diagram?
Which step is first in the process of creating a Data Flow Diagram?
Which of the following accurately describes interaction types in Data Flow Diagrams?
Which of the following accurately describes interaction types in Data Flow Diagrams?
Entity independence in Data Flow Diagrams indicates what?
Entity independence in Data Flow Diagrams indicates what?
What does proper labeling convention in Data Flow Diagrams ensure?
What does proper labeling convention in Data Flow Diagrams ensure?
Which characteristic is NOT associated with Data Flow Diagrams?
Which characteristic is NOT associated with Data Flow Diagrams?
Which Level of DFD is specifically concerned with identifying actual data flows and data stores?
Which Level of DFD is specifically concerned with identifying actual data flows and data stores?
In Data Flow Diagrams, what does a well-defined process typically achieve?
In Data Flow Diagrams, what does a well-defined process typically achieve?
Flashcards
Data Flow Diagram (DFD)
Data Flow Diagram (DFD)
A graphical representation of data flow and processing within an information system.
Data Flow Analysis
Data Flow Analysis
Identifying system activities, essential data, data inputs/outputs for a system.
Context Level DFD
Context Level DFD
The highest-level DFD that shows an overview of external entities interacting with the system.
Level 0 DFD
Level 0 DFD
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External Entity
External Entity
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Process
Process
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Data Store
Data Store
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Logical DFD
Logical DFD
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Check Inventory
Check Inventory
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Data Flows (DFDs)
Data Flows (DFDs)
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External Entities (DFDs)
External Entities (DFDs)
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Order Processing (Process)
Order Processing (Process)
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Validate Order
Validate Order
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DFD Diagram Rules for Process
DFD Diagram Rules for Process
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DFD Process Inputs
DFD Process Inputs
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Data Flow from Data Store to Process
Data Flow from Data Store to Process
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Data Flow from Process to Data Store
Data Flow from Process to Data Store
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DFD Data Flow Labels
DFD Data Flow Labels
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Context Diagram
Context Diagram
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DFD Stopping
DFD Stopping
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Study Notes
Data Flow Diagrams (DFDs)
- A graphical representation of data flow through an information system.
- Used to visualize data processing.
- Shows a system as a function transforming input to output.
- Data flow analysis identifies system activities and necessary data.
- Demonstrates data and logical flow within a system.
- Models a system using external entities, data flows, processes, and data stores.
Data Flow Diagram Characteristics
- Illustrates data passage through a system.
- Focuses on process transformations of input data into output data.
- Processes use and create data.
- External entities send and receive data.
- Uses a top-down approach for analysis.
Creating a Data Flow Diagram (DFD)
- List activities.
- Create a context level DFD (external entities and processes).
- Construct a level-0 DFD (identifies manageable sub-process).
- Construct level 1-n DFDs (identifies actual data flows and stores).
- Check against DFD rules.
Symbols Used in DFDs
- Entity: Represents people, companies, or outside systems.
- Data Flow: Shows data movement.
- Process: Represents actions transforming data.
- Data Store: Represents data storage locations.
External Entities (Source/Sink)
- Represent people or organizations outside the system.
- Show initial and final data recipients.
- Examples: Customers, suppliers, departments, other systems.
Processes
- Represent system activities or subsystems.
- Described as verb-adjective-noun phrases.
- Exceptions are system/subsystem processes.
Data Stores
- Named using nouns, describing data stored.
- Unique reference numbers (e.g., D1, D2).
- Include transaction files, computer files, databases.
Data Flow
- Shows data movement within a system.
- Named using nouns describing data.
- Arrowheads indicate flow direction.
- Double-headed arrows show data reading and updating.
Data Flow Diagram Errors
- A process containing only input or only output data flow.
- Data stores or external entities directly connected, in any combination.
- Incorrect labeling of data flows or objects.
- Processes labeled with nouns, data flows with verbs.
- Too many processes on a diagram (maximum of nine suggested).
- Omitting data flows.
- Unbalanced process decomposition between parent and child diagrams.
DFD Levels
- Context DFD (Level 0): Shows the system, external entities, and data flows.
- Level-0 DFD: Shows the system's major processes, data flows, and stores, at a high level of abstraction.
- Level-1 DFD: Shows the subprocesses of one process in the Level-0 DFD.
- Level-n DFD: Shows subprocesses for subsequent levels of decomposition.
DFD Guidelines
- Completeness: Include all necessary components.
- Consistency: Maintain consistent information across levels.
- Timing: Data flow diagrams should be depicted as if the system never starts or stops.
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Description
This quiz delves into the principles and characteristics of Data Flow Diagrams (DFDs). It covers their significance in visualizing data processing and system activities, as well as the symbols used in DFDs. Test your knowledge on how to create and analyze DFDs effectively.
