1.The number of symbols in data fow diagrams.
2. Type of phrase associated with a process
3. Descriptor for entities outside the system.
1. To determine the number of symbols in a data flow diagram (DFD), you need to understand the different types of symbols used in DFDs. Here are the main symbols used in DFDs and their meanings:
- Process symbol: This symbol represents a process or activity that transforms inputs into outputs. It is usually represented as a rectangle with rounded corners.
- Data flow symbol: This symbol represents the flow of data between processes, external entities, and data stores. It is usually represented as an arrow.
- External entity symbol: This symbol represents an external entity that interacts with the system. It could be a person, another system, or an organization. It is usually represented by a rectangle.
- Data store symbol: This symbol represents a place where data is stored within the system. It can be a physical database, a file, or even a simple data structure. It is usually represented as a rectangle with two parallel lines at the top and bottom.
- Control flow symbol: This symbol represents the flow of control or sequence of activities in a process. It is usually represented by a dashed or solid line with an arrowhead.
Counting the number of symbols in a DFD depends on the complexity and level of detail in the diagram. You would need to visually inspect the diagram and identify each symbol mentioned above, and count the occurrences of each symbol in the diagram to get the final count.
2. In a data flow diagram (DFD), the type of phrase associated with a process is called an action verb phrase. An action verb phrase describes what the process does or the action it performs. It typically consists of a verb and a noun (i.e., subject).
For example, if you have a process symbol representing the "Order Processing" activity in a DFD, the associated action verb phrase could be "Process Orders," "Handle Customer Requests," or "Validate and Approve Orders."
To define an action verb phrase for a process in a DFD, you can follow these steps:
- Identify the main purpose or function of the process.
- Choose a descriptive verb that best represents the action performed by the process.
- Combine the verb with a relevant noun or object to form a clear and concise phrase that describes the process activity.
Remember, the action verb phrase should accurately reflect the intended action of the process and provide a clear understanding of its purpose in the DFD.
3. In a data flow diagram (DFD), descriptors for entities outside the system are known as external entity labels. These labels provide a brief description or identification of the entities interacting with the system but exist outside the system boundaries.
External entity labels are usually placed adjacent to the external entity symbol (rectangle) representing the entity in the DFD. These labels should be concise, informative, and easily understandable to identify the external entities involved in the system.
For example, if an external entity represents a customer in an e-commerce system, the external entity label could be "Customer," "User," or "Buyer." Similarly, if an external entity represents a supplier, the label could be "Supplier" or the name of the specific supplier.
To determine the descriptor for entities outside the system, you need to identify all the external entities in the DFD and determine their associated labels based on their role or purpose in the system. The labels should be consistent and meaningful to facilitate clear communication and understanding of the system's external interactions.