What is the difference between physical and logical dfd

Logical architecture is a structural design that gives as much detail as possible without constraining the architecture to a particular technology or environment. For example, a diagram that illustrates the relationship between software components. For example, a specification of software services and components. What is a physical topology diagram? Physical topology refers to the interconnected structure of a local area network LAN.

The method employed to connect the physical devices on the network with the cables, and the type of cabling used, all constitute the physical topology. What is a logical view? Logical view: The logical view is concerned with the functionality that the system provides to end-users. UML diagrams are used to represent the logical view, and include class diagrams, and state diagrams. UML diagrams to represent process view include the activity diagram.

What is the difference between logical and physical models? The main aim of conceptual model is to establish the entities, their attributes, and their relationships.

Logical data model defines the structure of the data elements and set the relationships between them. A Physical Data Model describes the database specific implementation of the data model.

What is logical flow? The writing skill of 'logical flow' can be defined as all the aspects of your writing that help the reader move smoothly from one sentence to the next, and one paragraph to another. Another benefit of logical DFDs is that they tend to be more easily understandable to non-technical people. They will likely make sense to the people working in the business activities. They will serve as a bridge from business needs to technical requirements. The discipline of mapping out the current logical flow will help everyone involved to gain a deeper understanding and reveal mistaken assumptions, misunderstandings or shortcomings.

Doing logical models reduces the risk of missing business requirements that otherwise would arise belatedly in the process, causing delays and rework. Then, with a solid understanding of the current business activities, you can model a better way with a new state logical DFD , showing new features and functioning based on what the business analysis has revealed.

This new logical DFD models what data flows are necessary to create the better functioning, no matter what the technical solution or how the system will be implemented. After the new logical DFD is drawn, it in turn can be used to figure out the best method to implement the business activities in an upgraded system. This becomes the basis for the new physical DFD , depicting that physical implementation of devices, software, files and people to enable the business processes. In this sense, the physical DFD becomes the method of giving the business what it needs.

Rather than dive straight into reviewing new software, you start by mapping out the current logical data flow. You then map out a potential new logical flow. For example, it might provide timely alerts to hiring managers, keeping them better apprised. This new logical DFD is the basis for discussion of how to best implement better functioning in terms of software, hardware, filing systems and employees, all of which can be visualized in a physical DFD.

This can be used to assess software solutions and other implementation pieces and to see which best meets business needs. For example, you could show how different software platforms would vary in different versions of the physical DFD, helping to reveal the best solution. Diagramming is quick and easy with Lucidchart. Start a free trial today to start creating and collaborating. Data flow diagrams are composed of four elements: external entities, processes, data stores and data flows.

For example, in logical DFDs, the processes are business activities; in physical DFDs, the processes are software programs, manual procedures or other ways information is processed.

A logical DFD can capture current and necessary activities required for a process. A new logical DFD models a new set of activities and functions. A current physical DFD depicts the current software, hardware, databases and people to carry out the activities, and new physical DFD models a new system implementation. This analysis can provide a better way to get to the actual code that fuels the requirements.

In business analysis: A logical DFD can help to reveal business requirements that might otherwise go unstated until late in the process, causing delays and rework. It also serves as a clear communication tool with non-technical people involved in the business activities, both for the current flow of information and the proposed new way.

In structured analysis: In classical, top-down structured analysis, a logical DFD is drawn of a current system to describe its current state, and then an improved system is modeled in a new logical DFD.

Physical data flow diagrams have several advantages including:. There is a table to compare the features of logaical and physical data flow diagrams:.

Features Logical DFD Physical DFD Model Depicts Depicts how business operates Depicts how the system will be implemented or how the existing system functions Process Represents Represents business activities and functions Represents manual processes, programs and program modules Data Stores Represents Data is collected irrespective of how it is stored Databases along with physical and manual files Types of Data Stores Data stores containing a permanent collection of data are depicted Depicts master and transition files.

Any process that happens at two different times must be connected with data stores System Controls Represents the business controls System control is depicted for validation of input data, to supervise the completion of a process, and for the security of the system.

There is a comparison diagram illustrates the process of customer shopping process. From this, the main differences between logical and physical DFDs are that the payment ways and the action when calculating the final cost of the product showing below.

The above example is built in EdrawMax depicts a manual process of a buyer's journey from the beginning item selection to the end issuing of receipt. The diagram illustrates the movements of the item including key manual processes like bar code scanning and unique ID registration.

With EdrawMax, it is easier to create logical and physical data flow diagrams by choosing a built-in template from the templates gallery. The logical DFD describes what the system does by including the essential sequence of business activities. It model the business data and activities instead of actual forms, location and roles.

The logical DFD illustrates the processes involved without going into detail about the physical implementation of activities.

Note that the Context Diagram did NOT record the movement of merchandise, but rather the information flow surrounding the underlying business processes. Let's summarize their differences:. We use cookies to offer you a better experience.