A Beginner’s Guide to Data Flow Diagrams

Ask any skilled athlete or enterprise government how they turned profitable, they usually’ll let you know they mastered a course of. By determining which habits led to success and which didn’t, they improved their effectivity and productiveness.

However implementing a course of right into a enterprise, division, or perhaps a group is a very totally different animal than honing your private course of. With so many transferring components, how do you observe and refine every facet of what you are promoting course of?

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Knowledge circulate diagrams present an easy, environment friendly method for organizations to know, good, and implement new processes or techniques. They’re visible representations of your system, making it simple to know and prune.

Earlier than we dive into how knowledge circulate diagrams can assist refine any of what you are promoting techniques or processes, let’s go over what precisely it’s.

Picture Supply

DFDs turned well-liked within the Nineteen Seventies and have maintained their widespread use by being simple to know.

There are two sorts of DFDs — logical and bodily. Logical diagrams show the theoretical strategy of transferring data by a system, like the place the info comes from, the place it goes, the way it modifications, and the place it finally ends up.

Bodily diagrams present you the sensible strategy of transferring data by a system. It could actually present how your system’s particular software program, {hardware}, information, staff, and prospects affect the circulate of knowledge.

You possibly can both use logical or bodily diagrams to explain that circulate of knowledge. You may as well use them in conjunction to know a course of or system on a extra granular stage.

The Advantages of Knowledge Circulate Diagrams

DFDs are visible representations that may assist nearly anybody grasp a system‘s or course of’ logic and features. Except for being accessible, they supply much-needed readability and enhance productiveness. Here is how.


As a result of visible data is less complicated to digest, DFDs sometimes clarify complicated ideas higher than blocks of textual content can.

Visible displays of how a course of works also can maintain folks’s consideration longer — making it simpler to retain the data.


DFDs make clear the techniques and processes mandatory to your group to do their greatest work. Whether or not implementing a brand new company-wide system or refining a division’s current course of, a DFD will get you and your group on the identical web page.

Creating DFDs gives you readability about enterprise operations, too. A clearer understanding allows you to refine and observe what you are promoting processes with much less friction.


The accessibility and readability created with DFDs will go away much less room for error. Your group will higher grasp techniques and processes as a result of they perceive them.

Better understanding — paired with a repeatable course of — will possible increase group effectiveness and productiveness.

On a broader stage, DFDs can assist you streamline what you are promoting operations. When mapping out your processes, you‘ll acquire insights into what does and doesn’t work.

These insights assist increase you and your group’s productiveness. As a bonus, you possibly can share any greatest practices throughout departments.

Knowledge Circulate Diagram Symbols

Earlier than utilizing a DFD, it’s good to know the symbols used to explain it.

Knowledge circulate diagram symbols are standardized notations, like rectangles, circles, arrows, and short-text labels. These symbols characterize a system’s knowledge circulate route, inputs, outputs, storage factors, and sub-processes.

4 widespread strategies of notation are utilized in DFDs: Yourdon & De Marco, Gene & Sarson, SSADM, and Unified.

All use the identical labels and related shapes to characterize the 4 essential parts of a DFD — exterior entity, course of, knowledge retailer, and knowledge circulate.

1. Exterior Entity

Exterior entities — that are also referred to as terminators, sources, sinks, or actors — are exterior techniques that ship or obtain knowledge to and from the diagrammed system.

They’re both the sources or locations of knowledge, so that they’re normally positioned on the diagram’s edges.

Exterior entity symbols are related throughout fashions apart from Unified, which makes use of a stick-figure drawing as a substitute of a rectangle, circle, or sq..

2. Course of

Course of is a process that manipulates the info and its circulate by taking incoming knowledge, altering it, and producing an output. A course of can do that by performing computations and utilizing logic to kind the info or change its circulate of route.

Processes normally begin from the highest left of the DFD and end on the underside proper of the diagram.

3. Knowledge Retailer

Knowledge shops maintain data for later use, like a file of paperwork that’s ready to be processed. Knowledge inputs circulate by a course of after which by an information retailer, whereas knowledge outputs circulate out of an information retailer after which by a course of.

4. Knowledge Circulate

Knowledge circulate is the trail the system’s data takes from exterior entities by processes and knowledge shops. With arrows and succinct labels, the DFD can present you the route of the info circulate.

DFD Ranges

DFDs can vary from easy overviews to complicated, granular representations of a system or course of with a number of ranges, beginning with stage 0.

The commonest and intuitive DFDs are stage 0 DFDs, additionally known as context diagrams. They’re digestible, high-level overviews of the circulate of knowledge by a system or course of, so nearly anybody can perceive it.

Stage 0: Context Diagram

This DFD stage focuses on high-level system processes or features and the info sources that circulate to or from them. Stage 0 diagrams are designed to be easy, simple overviews of a course of or system.

Stage 1: Course of Decomposition

Whereas stage 1 DFDs are nonetheless broad overviews of a system or course of, they’re additionally extra detailed — they break down the system’s single course of node into subprocesses.

Stage 2: Deeper Dives

The following stage of DFDs dives even deeper into element by breaking down every stage 1 course of into granular subprocesses.

Stage 3: Rising Complexity

Stage 3 and higher-numbered DFDs are unusual. That is largely because of the quantity of element required, which defeats its authentic objective of being simple to know.

Knowledge Circulate Diagram Examples

Professionals in varied industries, like software program engineering, IT, ecommerce, and product administration & design, can use DFDs to raised perceive, refine, or implement a brand new system or course of.

However what does an information circulate diagram seem like in follow — and the way does it assist what you are promoting? Listed here are three examples that will help you contextualize DFDs’ impression.

1. Stage 0 DFD

This Stage 0 DFD gives a contextual map of a securities buying and selling platform.

Knowledge flows in a single route from the customer support assistant and the dealer to the platform. It additionally flows in two instructions from prospects to the platform and again once more.

2. Stage 1 DFD

This Stage 1 DFD breaks down the shopper course of in additional element, increasing it to incorporate account creation, money withdrawals, and eventual securities transactions.

3. Stage 2 DFD

This Stage 2 DFD decomposes the “Place Order” course of to contextualize the steps required to position an order — both by a buyer or by a dealer.

It even accounts for a third-party inventory alternate middle the place transaction particulars are forwarded after an order is positioned.

1. Know the fundamentals.

Earlier than you begin mapping out knowledge circulate diagrams, it’s good to observe 4 greatest practices to create a legitimate DFD.

  1. Every course of ought to have no less than one enter and one output.
  2. Every knowledge retailer ought to have no less than one knowledge circulate in and knowledge circulate out.
  3. A system’s saved knowledge should undergo a course of.
  4. All processes in a DFD should hyperlink to a different course of or knowledge retailer.

2. Choose a system or course of.

Start by choosing a selected system or course of you wish to analyze. Whereas any system or course of will be changed into a DFD, the bigger the method, the extra difficult the diagram and the harder it is going to be to contextualize.

Wherever attainable, begin with a small perform or course of you’re trying to enhance.

3. Categorize associated enterprise actions.

Subsequent, categorize all actions associated to this course of into exterior entities, knowledge flows, processes, and knowledge shops.

Take into account a restaurant meals ordering system. Clients are exterior entities, the meals ordering system is a course of, and the interplay between prospects and the system (which matches in each instructions) is the circulate.

Additionally value noting? The ordering system doubles as an information retailer, so for an SSADA mannequin, this implies drawing it as a rectangle with rounded corners with two horizontal traces inside to characterize its twin perform.

4. Draw a context DFD.

Now it’s time to start out drawing. DFDs will be created by hand, utilizing free templates obtainable on-line, or through browser extensions.

Start with a easy, Stage 0 DFD: Begin together with your course of or system, then map all primary connections and flows.

5. Test your work.

Earlier than diving into extra complicated DFDs, examine the work you’ve already completed to verify it’s correct and full.

For those who’ve missed (or added) a course of, entity, or circulate, your next-level DFDs could not make sense, and it’s possible you’ll be pressured to start out over.

6. Create little one diagrams.

For every course of or system described in your Stage 0 DFD, create a brand new little one diagram with its personal entities and flows. Finally, you need to use these little one diagrams to attach processes collectively.

7. Develop processes into Stage 1 DFDs.

Utilizing your little one diagrams, you must map extra in-depth connections between every course of.

Within the case of our restaurant instance, this might imply digging deeper into the meals ordering system and its connection to suppliers, managers, prospects, and kitchen employees.

8. Repeat as wanted.

Every course of — irrespective of how massive or small — will be reimagined as a Stage 0 context diagram, and the cycle can start once more.

Repeat these steps as wanted to create as many DFDs as required, or break processes down additional to develop Stage 2, 3, and many others. DFDs.

Perfecting Your Course of

Whereas there’s no such factor as a “good” knowledge circulate diagram, continued follow can assist streamline the method and supply essential perception into what’s working, what isn’t, and the place what you are promoting could make impactful enhancements.

Your greatest guess? Keep in mind the rule: Hold it easy. Begin with context, construct out related processes, and repeat as wanted to map key connections, flows, and entities throughout your group.

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