When your team is working on a new system or is trying to update one, it is important to take a look at both internal and external factors. There are numerous tools and techniques to evaluate everything that might affect the outcome. A context diagram is one of the tools that helps you keep track of all the external factors that interact and affect your system. If you take a look at a context diagram example, you will understand what a useful technique it really is.
Keep the context view alongside your system architecture diagrams so reviewers can distinguish external relationships from the components inside the system.
A context diagram helps a team agree on a system’s boundary before discussing its internal design. This guide explains the main symbols, shows three existing examples, and demonstrates how to describe the information crossing that boundary.
What Is a Context Diagram
In essence, a context diagram is a visual representation of the system and the way it interacts with all of its external factors. To make this explanation simpler, it consists of a set of shapes that connect with the use of arrows. This way, you can quickly view the factors surrounding the system and what their relationship is like.
Figure 1. Context Diagram Example
The main elements that you can find in any context diagram example are the system, the external factors, and the data flows. Each one of these is noted by a different shape that distinguishes it from the rest. The point of this tool is to highlight the relationship between these shapes through a visual representation of their interaction.
In the context diagram example (Figure 1), this tool permits you to view at a glance all the factors that you need to keep in mind. In data-flow modeling, a context diagram represents the entire system as one process. Some conventions call this Level 0; others reserve Level 0 for the next, decomposed view. State the convention when sharing your diagram.
Pros and Cons of a Context Diagram
Taking all of the above into consideration, it is easy to understand that a context diagram is a truly useful tool. Nevertheless, it would be a good idea to take a look at its advantages and disadvantages in more detail.
Comparison Between the Context Diagram and Flow Diagram
A context diagram and a flowchart answer different questions. The context view shows what lies outside a system and what it exchanges with those external entities. A flowchart shows the sequence of actions and decisions. A context diagram drawn using data-flow notation is the highest-level view of a DFD, not simply a shorter process flowchart.
Figure 2. Data Flow Diagram Example. Source: Software Ideas Modeler
By comparing the context diagram example (Figure 1) and the data flow diagram example (Figure 2), their connection becomes apparent. However, their difference gets also highlighted.
In more detail, the data flow diagram is more detailed compared to the context diagram. The most important thing that is missing from the last is the data storage element. A decomposed DFD can show internal processes and data stores as well as external entities and data flows. The context view deliberately leaves internal processes and stores inside its single system boundary.
To move from a detailed DFD to a context view, represent the system as one process and retain the flows that cross its boundary. Do not keep internal stores as outside entities merely because they were visible in the detailed diagram. The Visual Paradigm DFD guide explains the distinction between the context view and lower-level diagrams.
Create a Context Diagram Step by Step
After discussing the theory of the context diagram, it is time to explore its components and how to create one. Then, it will become clear to you how to create a context diagram of your system.
Learn About the Basic Component
Before you start designing a context diagram example, you must understand the basic elements that appear in the sketch. As we have already mentioned, these are the system, the external factors, and the data flows.
In more detail, the basic components of a context diagram are the following:
- The system – the system is noted by a circle, which is usually placed in the center of the context diagram.
- The external factors – every factor that is outside of the system is placed in squares and rectangles around the system’s circle. To make the diagram easier to understand, make sure you note what each rectangle represents.
- The data flow – the system and each factor are connected by the flow lines, which are indicated by arrows. The arrow can either come from the system to the external factor, or from the external factor to the system. This way, you can view how they interact and affect each other.
All of these components are enough to showcase the interactions between your system and its external factors. You can also write beside every shape more details that will help your team get a better understanding of these relationships.
Tips for Creating a Context Diagram
If you want to try creating a context diagram example for your team, then you must follow some simple rules. This way, you can rest assured that you have created a diagram with all the information needed. Here are some tips to help you design a context diagram example:
- Place your system at the center of your screen to build your diagram – the first thing that you must do is create a circle and place it at the center of your canvas. This will indicate your system.
- Note all external entities that interact with your system – then, you must take the time to identify all the external factors that play an important role. These will be indicated by the various rectangles that you will place around the system’s symbol.
- Recognize how the data flows between your system and the external factors – your context diagram wouldn’t be complete without noting how the elements interact with each other. Make sure that the arrows showing the data flows are pointing in the right direction.
- Frequently evaluate your context diagram – creating this diagram isn’t just a one-time thing. You also need to revisit it and evaluate whether these interactions still stand or if there are some new ones that you need to add.
- Share the result with every team member – lastly, you are ready to share your diagram with your whole team, and even the stakeholders. By selecting the right online tool, you can quickly share the file and receive feedback.
Create a Context Diagram with Boardmix
Even though creating a context diagram example shouldn’t be that difficult, the process will become so much easier and more intuitive with the right tool.
Boardmix is an online whiteboard tool that is perfect for creating any diagram you might need. For instance, it is ideal for a context diagram, flow chart, user story map, and organization chart among others.
What makes Boardmix a great choice for your team is that it focuses on collaboration. Share the board with the people who need to review the boundary and choose appropriate viewing or editing permissions. Access and editing depend on those permissions. All these interactions are shown in real time, thus making it easier for team members to work together and brainstorm.
3 Classic Context Diagram Examples
To better understand what a context diagram is, we are going to take a look at three classic examples of it. This way, you can have an idea of what you need to include in the context diagram example that you will propose for your system.
Example 1
Figure 4. Example of an Online Community. Source: Modern Analyst
In the online-community example, Community Users send Registration information and receive Information & Tools. Staff Writers send Content and receive Compensation. These labels distinguish the exchanges in each direction. If you adapt the diagram for a posting or moderation service, add the relevant flows rather than assuming they are already shown.
Example 2
Figure 5. Example of an Online Store. Source: University of Waterloo
The sales-order example places Managers, Employees and Customers outside the Sales order system. Follow the labeled arrows: customers provide Customer information and receive an Order Invoice, while employees provide Product and Category data. In your own diagram, name each exchange and check its direction; add a payment provider only if that separate service is within the scope you are modeling.
Example 3
Figure 6. Example of a Library Management System. Source: Mind on Map
The library example shows Students, Staff, Supplier and Management around the central system, and it also places Book Database and Student Database outside. That last choice needs a boundary decision: if those databases belong to the library system, keep them inside its single context boundary rather than drawing them as external entities. Show an external data service only when it is separately managed. The Request/Reply and Reports arrows illustrate exchanges whose directions and labels should also be checked.
Regardless of the system you are working on, you need to create a context diagram example when needs arise. This tool will help you recognize how your system gets affected by all external factors, which will improve its overall quality. Boardmix is the perfect tool to create and share your context diagrams quickly. Try the platform and discover its collaborative features that will bring your team together.
