It also shows the major technology choices and how the containers communicate with one another. Primary elements : Containers within the software system in scope. Supporting elements : People and software systems directly connected to the containers. Notes : This diagram says nothing about deployment scenarios, clustering, replication, failover, etc. Next you can zoom in and decompose each container further to identify the major structural building blocks and their interactions.
Primary elements : Components within the container in scope. Supporting elements : Containers within the software system in scope plus people and software systems directly connected to the components. Intended audience : Software architects and developers.
Recommended for most teams : No, only create component diagrams if you feel they add value, and consider automating their creation for long-lived documentation. See example diagram and narrative.
Finally, you can zoom in to each component to show how it is implemented as code; using UML class diagrams, entity relationship diagrams or similar. This is an optional level of detail and is often available on-demand from tooling such as IDEs. Ideally this diagram would be automatically generated using tooling e. This level of detail is not recommended for anything but the most important or complex components.
Primary elements : Code elements e. Recommended for most teams : No, for long-lived documentation, most IDEs can generate this level of detail on demand. Once you have a good understanding of the static structure, you can supplement the C4 diagrams to show other aspects.
The C4 model provides a static view of a single software system but, in the real-world, software systems never live in isolation. For this reason, and particularly if you are responsible for a collection of software systems, it's often useful to understand how all of these software systems fit together within the bounds of an enterprise.
To do this, simply add another diagram that sits "on top" of the C4 diagrams, to show the system landscape from an IT perspective. Essentially this is a high-level map of the software systems at the enterprise level, with a C4 drill-down for each software system of interest. From a practical perspective, a system landscape diagram is really just a system context diagram without a specific focus on a particular software system.
Primary elements : People and software systems related to the enterprise in scope. Intended audience : Technical and non-technical people, inside and outside of the software development team. A dynamic diagram can be useful when you want to show how elements in a static model collaborate at runtime to implement a user story, use case, feature, etc.
It is similar to a UML sequence diagram although it allows a free-form arrangement of diagram elements with numbered interactions to indicate ordering. Scope : An enterprise, software system or container. Primary and supporting elements : Depends on the diagram scope; enterprise see System Landscape diagram , software system see System Context or Container diagrams , container see Component diagram.
This deployment diagram is based upon a UML deployment diagram , although simplified slightly to show the mapping between containers and deployment nodes. A deployment node is something like physical infrastructure e. IaaS, PaaS, a virtual machine , containerised infrastructure e. Deployment nodes can be nested.
You may also want to include infrastructure nodes such as DNS services, load balancers, firewalls, etc. Primary elements : Deployment nodes, software system instances, and container instances. Supporting elements : Infrastructure nodes used in the deployment of the software system. The C4 model doesn't prescribe any particular notation. A simple notation that works well on whiteboards, paper, sticky notes, index cards and a variety of diagraming tools is as follows.
You can then use colour and shapes to supplement the diagram, either to add additional information or simply to make the diagram more aesthetically pleasing. Although the example diagrams above are created using a "boxes and lines" notation, the core diagrams can be illustrated using UML with the appropriate use of packages, components and stereotypes.
The resulting UML diagrams do tend to lack the same degree of descriptive text though, because adding such text isn't possible or easy with some UML tools. Here are three examples of a System Context, Container and Component diagram for comparison. Although the C4 model is an abstraction-first approach and notation independent, you still need to ensure that your diagram notation makes sense, and that the diagrams are comprehensible.
A good way to think about this is to ask yourself whether each diagram can stand alone, and be mostly understood without a narrative. You can use this short software architecture diagram review checklist to help.
Part of Simon's training course was a design exercise, where groups of people were given some requirements, asked to do some design, and to draw some diagrams to express that design. Although this was a design focussed exercise, the wide variety of diagrams made it evident that the visualisation of ideas was a skill that most people sorely lacked. The C4 model is essentially a formalisation of how Simon used to visualise software architecture, which has evolved over the years.
The roots of the C4 model, and the various diagram types within it, can be traced back to somewhere in the region of , although the "C4" name came much later, around the end of It was created during a time where teams, influenced by the agile movement, were less than enthusiastic about using UML. Whether you see the C4 model as a step forwards or a step backwards depends upon where you are. Unfortunately, UML usage seems to be in decline, and many teams have reverted to using ad hoc boxes and lines diagrams once again.
Given that many of those teams don't want to use UML for various reasons , the C4 model helps introduce some structure and discipline into the way software architecture is communicated. For many teams, the C4 model is sufficient. And for others, perhaps it's a stepping stone to UML. The honest answer is that nobody knows.
Simon has personally taught the C4 model to somewhere over 10, people in more than 30 countries; with conference talks, videos, books and articles reaching many more than this. Other people are also teaching, speaking and writing about the C4 model too.
It's definitely being used though, in organisations ranging from startups to global household names. Terms like "process", "application", "app", "server", "deployable unit", etc all have associated implications, so the name "container" was chosen as a generic way to describe something in which components live.
From one perspective, it's unfortunate that containerisation has become popular, because many software developers now associate the term "container" with Docker. From another perspective though, there is sometimes a nice parity between a container in the C4 model and an infrastructure e.
Docker container. While many teams successfully use the C4 model as is, feel free to change the terminology if needed. This terminology context, containers, components and code works for many organisations and many types of software.
However, sometimes an organisation will have an existing terminology that people are already familiar with. Or perhaps "components" and "classes" don't easily map on to the technology being used e. Feel free to modify the terminology that you use to describe software architecture at different levels of abstraction.
Just make sure that everybody explicitly understands it. Broadly speaking, there are two options for diagramming microservices when using the C4 model, although it depends what you mean by "microservice". Approach 1: Each "microservice" is owned by a separate team If your software system has a dependency upon a number of microservices that are outside of your control e.
Even with a relatively small software system, it's tempting to try and include the entire story on a single diagram. For example, if you have a web application, it seems logical to create a single component diagram that shows all of the components that make up that web application. Unless your software system really is that small, you're likely to run out of room on the diagram canvas or find it difficult to discover a layout that isn't cluttered by a myriad of overlapping lines.
Using a larger diagram canvas can sometimes help, but large diagrams are usually hard to interpret and comprehend because the cognitive load is too high. And if nobody understands the diagram, nobody is going to look at it. Instead, don't be afraid to split that single complex diagram into a larger number of simpler diagrams, each with a specific focus around a business area, functional area, functional grouping, bounded context, use case, user interaction, feature set, etc.
The key is to ensure that each of the separate diagrams tells a different part of the same overall story, at the same level of abstraction. See also Diagramming vs modelling for an alternative approach. Due to the hierarchical nature of the C4 model, each diagram will change at a different rate. The focus of the C4 model is the static structures that make up a software system, at different levels of abstraction. Often this is because teams don't know these notations well enough, perceive them to be too complicated, think they are not compatible with agile approaches or don't have the required tooling.
If you are already successfully using one of these notations to communicate software architecture and it's working, stick with it. If not, try the C4 model. And don't be afraid to supplement the C4 diagrams with UML state diagrams, timing diagrams, etc if you need to. Our app includes first-class support for elements you're familiar with and care about.
Link directly from diagram to lines of code, or any other external documentation. Automatically sync diagrams to a Github repository. Whenever there are changes, our bot pushes revisions to a repository of your choice. Collaborate with your teammates seamlessly.
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. It would include only a newly created system and a single customer, which didn't bring any value.
That way the context diagram started to make sense and allowed to omit those elements from the lower level diagrams. Given the amount of vectors in this Stencil, when OmniGraffle helped me a great deal achieve that goal. I created this stencil to help throw ideas on a 'digital' white board and conduct brainstorming sessions with remote team members via screen sharing.
Hope you find Set of elements for the visualization of a microservice architecture for web applications.
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