The first two diagrams show how the elements of the system relate to each other. However, they can not demonstrate what happens in your system.
For example, a user sign ups for your system. Which components are involved? What actions are triggered? How the components interact with each other? Sequence diagram can answer these questions. At the top we see interacting entities: persons, web and mobile applications, external systems, services and data stores. Each entity has a vertical line underneath. The interaction between services is notated with horizontal arrows between the vertical lines.
Those arrows can be of different types depending on whether this is a synchrornous operation or an asynchronous. The grey rectangles shows that process is taking some time and the length should indicate the duration: the longer the rectangle, the longer the time.
Unfortunately, OmniGraffle is not suitable for sequence diagrams. Therefore I use draw. The latter is a good choice because you can choose either to draw the diagram manually or use the UML Sequence diagramming.
This is possible as Sequence Diagram is a structured one. Using context, containers and sequence diagrams you can answer what parts of the system consist of and how they relate and interact with each others.
But they hardly can answer the questions of availability, scalability and security. Deployment diagram helps with that. Compute resources. This can include virtual machines, docker containers, kubernetes clusters and cloud functions.
You can also think of mobile devices and desktop computers as compute resources as well. Persistent storages for your data like relational and nosql databases, binary file storages like images, music and video, bigdata storages with parket files and so on.
Messaging resources. Your computers use networks to communicate with each others. Both physical and virtual networks should be displayed. The diagram shows the compute, storage and messaging resources alongside with networks and availability zones. It also includes the instrastructure nodes which are not fulfilling any functional requirements, but addressing non-functional instead.
There are plenty of tools to create a deployment diagram. OmniGraffle, LucidChart, Draw. Deployment diagram complements the understanding of the system from the physical appearence perspective. The most of previous diagrams were very technical ones.
Use Case diagram is more business oriented. It depicts how the persons are interacting with your system in a very high level way. Use cases themselves can be treated as business capabilities, which I were describing in this article. The architect can draw a diagram with any graphical editor and with the same toolset used for other diagrams. Omnigraffle, LucidChart, Draw. PlantUml or LucidChart helps with that. Discuss this article on twitter. If you like the article, make sure to Subscribe for the upcoming articles!
Context The c4 website does a pretty good job explaining their diagrams, but I still would like to provide my own understanding. Example Context diagram This diagram displays the neo-banking digital platform presented by a blue rectangle in the center. How to draw Identify the persons who will use your system Identify the external systems Create a single rectangle depicting your system Add connections between the system, users and external systems Provide meaningful comments on every component Tools There are different tools you can use to create the context diagram.
Let's say we want to draw the aforementioned diagram for a neo-banking digital platform with uml: startuml! Important highlights Context diagram is the first thing you create when working on a system.
Failing to do so may cost you missed integrations and mistakes during system design. Context may actually include some lower level details, this is perfectly fine. I was struggling with a context diagram for one banking system. Also, although there would be two players we don't represent each player as an external entity. They both effectively send and receive the same data flows so it would be redundant. You will also notice that it leaves a lot of questions unanswered regarding the nature of the game.
Is it single player vs a n AI or multiplayer or both? For a game, the nature of the interactions are the main focus of the system as opposed to creating and managing data. A context diagram is still a useful diagram to create in developing a game, it's just not as useful as when developing an information based system.
Creating a context diagram is easy. Creating a context diagram which is an accurate representation of your system can be hard. Expect to go through several iterations, modifying your diagram as your understanding of the problem improves.
These diagrams are created as a process to help you by encouraging you to consider the project from a variety of perspectives. As such, the main value in them is the thinking you do whilst creating and updating them as opposed to viewing them after they are finished. You should consider these diagrams never finished but a work in progress.
Don't aim for perfection. These diagrams are a tool, not a product. You want to put enough time and effort into them that they achieve their purpose but not so much that they detract from your core purpose which is developing the best system you can. You are genearlly creating a context diagram as part of your software design and development, or to answer a question in an exam. The following steps can make the process smoother:.
Step 1: Draw a circle in the center of your document and label it with a reasonable name for the system. Step 2: Think about who your external entities are and draw these in. This can be tricky. It can be useful to first think about who your system is producing information for.
Then work backwards and think about where you will get the data from in order to do this. Step 4: Work out what data will be required in order to produce the data flows in step 3 and add these in as well. Step 5: Discuss this diagram with the client or other important stakeholders and ensure that your understanding of the problem is the same as theirs.
This is generally an easier task. In doing this you are normally provided a scenario which you are to create a context diagram for. The nature of this also dictates that it is usually quite a simple scenario and hence diagram you are asked to draw out as well.
Maybe think about noting these down, just to the side as well. Step 2: Draw a circle in the center of your answer area and label it with a reasonable name for the system don't just write down 'system'. Step 3: Draw a rectangle for each of the external entities and label them.
A group of runners do a weekly run in a park. The number of runners partaking in the run is increasing and the organisers would like a system to help them keep track of everyones runs. Each runner will get a runner id which will be printed as a QR code on a band the runners wear. The QR code will be scanned by a timekeeper as they complete the run. Their time taken will be stored in a database and runners can get a listing of times for all their runs from the system.
The organisers can also get a report telling them how many people ran each week and other statistics. A photographer may be present and can upload pictures of the run into the system as well.
Show suggested highlighting : external entities , data flows. A common mistake is to consider the database as an external entity.
It is in fact part of the system and so is not medelled within a context diagram. Storage mechanisms for the data will be looked at in Data Flow Diagrams which follow on from Context diagrams. Making presentations and reports enhanced with visuals and diagrams has never been easier. SmartDraw makes working with other tools seamless. Diagram Software Easily create data flow diagrams, network diagrams, org charts, and other diagrams Start Now.
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