Coffee Machine: Concept Level


The concept level defines the problem we are trying to solve. For the espresso machine, we are going to use diagrams at this abstraction level to answer questions like:

  • Who will use the machine and what are their goals while using it?

  • What sequence of events will a person take while operating the machine?

  • What are the key features and capabilities required for the machine to perform its intended function?

  • What are the design constraints and requirements that must be considered when designing the machine?

  • What are the key performance metrics that the machine must meet in order to be considered successful?

  • How will the machine fit into the larger context of the café, and how will it interact with other systems and components within the café?

  • What are the needs of others like those marketing, selling, manufacturing, or buying the machine?

At this level, the focus is on understanding the big picture of the espresso machine and its role within the café system. The answers to these questions will help guide the design and development of the machine at the logical and technology levels of abstraction.

Use Case Diagram

First the ants work on the behavior of the system. Expand the Behavior package in the Model Browser and double-click on the diagram named Use Cases.

A use case diagram is a type of visual representation used in systems engineering to describe the functional requirements of a system, such as an espresso machine. In the context of the espresso machine, a use case diagram would be used to identify and define the different ways in which the machine will be used by its users, such as the café staff and customers.

The diagram would typically include different actors or users, such as the barista, the customer, and possibly a manager or maintenance technician. It would also include different “use cases” or scenarios, which describe the different actions that the users can take with the machine, such as placing an order, making an espresso, or cleaning the machine.

The use case diagram helps to ensure that all the necessary functional requirements of the espresso machine are identified and accounted for, and that the system is designed to meet the needs of its users. It can also be used as a communication tool between the different stakeholders involved in the development of the machine, such as the ants and Cappuccino the cat.

The ants need your help updating the diagrams, so let’s get started:

  1. Double-click on the actor to pop up the rename dialog, and replace User with Barista.

  2. Update the name of the oval Use Case from Use Case #1 to Brew espresso.

  3. Update the name of the rectangle Block from Feature to Espresso Machine

A barista interacts with the espresso machine. The barista is provided a simple interface with a few push buttons.

In this particular use case diagram, we have one actor named Barista and one use case called Brew espresso, which is allocated to a block called Espresso Machine. The actor, in this case, is a cat barista who interacts with the system (an espresso machine) to accomplish a particular task, which is brewing espresso.

Use case diagram showing an actor named Barista and a use case called Brew espresso

The use case Brew espresso represents a specific functionality or action that the system (the Espresso Machine block) can perform. It describes the steps or interactions necessary to complete the task of brewing espresso, such as selecting the appropriate settings, starting the brewing process, and stopping the process once it’s complete.

The use case diagram shows the relationship between the actor and the use case. It is represented by an oval shape with the use case name inside and an association with the actor. The association represents the interaction from the actor to the use case.

Domain Diagram

A domain diagram is a graphical representation of the concepts, terms, and relationships within a specific domain. In the case of a coffee shop, a domain diagram could represent the key elements and relationships within the coffee shop domain.

The following is a domain diagram that builds upon the context diagram with additional blocks:

  • Barista

  • Coffee Machine

  • Roasted Coffee

  • Coffee Grinder

  • Water Supply

  • Customer

Each block in the Block Definition Diagram (bdd) represents a key concept within the coffee shop domain, and the containment relationship is used between the domain and the blocks to show that they are part of the domain.

Block Definition Diagram showing hierarchy of blocks in the Coffee Shop domain

The Barista block is responsible for preparing and serving the coffee to the customers. The Roasted Coffee block contains the types of coffee available for the barista to use. The Coffee Grinder block grinds the roasted coffee beans to the desired consistency before brewing. The Water Supply block contains the water source for the coffee machine, and finally the Customer block represents the person who orders and receives the coffee.

The ants need more of your help to rename the Feature Domain diagram and update it so that it matches the one above. Make sure that “Profile: SysML” is selected in the top-left corner of the Gaphor user interface. The names of the blocks can be changed directly in the diagram, but the name of the bdd can only be changed in the Model Browser. In the Structure package, right-click on the Blocks with the B symbol and rename them from the context menu. Also remember that you can use auto-layout to align and distribute all elements.

The domain diagram provides a high-level view of the coffee shop domain and the key concepts and relationships involved in it. It can be a useful tool for understanding the relationships between different elements of the domain and for communicating these relationships to others.

Context Diagram

The context diagram is a high-level view of the system, and it shows its interaction with external entities. In the case of a coffee machine, a context diagram provides a clear and concise representation of the system and its interactions with the external environment.

The context diagram for a coffee machine shows the coffee machine as the system at the center, with all its external entities surrounding it. The external entities include the barista, the power source, the coffee grinder, and the water source.

Block definition diagram showing context of the coffee shop with external entities

The ants need more of your help to rename the Feature Context diagram and update it so that it matches the one above. To create the specific arrows shown, use an Association entity, then toggle Enable Item Flow to on for that association and fill in the Item Property field.

Overall, the context diagram for a coffee machine provides a high-level view of the system and its interactions with external entities. It is a useful tool for understanding the system and its role in the broader environment.

Concept Requirements

Concept requirements are typically collected by analyzing the needs of the stakeholders involved in the development of the coffee machine. This involves identifying and gathering input from various stakeholders, such as the barista, the other engineers working on the product, manufacturing, and service.

To collect concept requirements, stakeholders may be asked questions about what they want the coffee machine to do, what features it should have, and what problems it should solve. They may also be asked to provide feedback on existing coffee machines to identify areas where improvements could be made.

Once the needs of the stakeholders have been gathered, they can be analyzed to identify common themes and requirements. This information can then be used to develop the concept requirements for the coffee machine, which serve as a starting point for the design process.

The following are some concept requirements for a coffee machine that addresses a water tank, heat-up time, and HMI button:

  • Water Tank: The coffee machine shall have a water tank of sufficient size to make multiple cups of coffee before needing a refill. The water tank should be easy to access and fill.

  • Heat-up Time: The coffee machine shall have a heat-up time of no more than 10 minutes from the time the user turns on the machine until it’s ready to brew coffee.

  • 1 Cup Button: The coffee machine shall have an HMI with a 1 cup brew button to make it easy for the user to select the amount of coffee they want to brew.

Concept requirements for water tank, heat-up time, and HMI button

Help the ants update the Concept Requirements diagram with these requirements.

Throughout the design process, the concept requirements will be refined and expanded upon as more information becomes available and the needs of the stakeholders become clearer. This iterative process ensures that the final design of the coffee machine meets the needs of all stakeholders and delivers a high-quality product.