Diagrams¶

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Flow Chars¶

Flowcharts are diagrams that represent workflows or processes. The steps are rendered as nodes of various kinds and are connected by edges, describing the necessary order of steps:

``` mermaid
graph LR
  A[Start] --> B{Error?};
  B -->|Yes| C[Hmm...];
  C --> D[Debug];
  D --> B;
  B ---->|No| E[Yay!];
```

graph LR
  A[Start] --> B{Error?};
  B -->|Yes| C[Hmm...];
  C --> D[Debug];
  D --> B;
  B ---->|No| E[Yay!];

Sequence Diagrams¶

Sequence diagrams describe a specific scenario as sequential interactions between multiple objects or actors, including the messages that are exchanged between those actors:

``` mermaid
sequenceDiagram
  autonumber
  Alice->>John: Hello John, how are you?
  loop Healthcheck
      John->>John: Fight against hypochondria
  end
  Note right of John: Rational thoughts!
  John-->>Alice: Great!
  John->>Bob: How about you?
  Bob-->>John: Jolly good!
```

sequenceDiagram
  autonumber
  Alice->>John: Hello John, how are you?
  loop Healthcheck
      John->>John: Fight against hypochondria
  end
  Note right of John: Rational thoughts!
  John-->>Alice: Great!
  John->>Bob: How about you?
  Bob-->>John: Jolly good!

State Diagrams¶

State diagrams are a great tool to describe the behavior of a system, decomposing it into a finite number of states, and transitions between those states:

``` mermaid
stateDiagram-v2
  state fork_state <<fork>>
    [*] --> fork_state
    fork_state --> State2
    fork_state --> State3

    state join_state <<join>>
    State2 --> join_state
    State3 --> join_state
    join_state --> State4
    State4 --> [*]
```

stateDiagram-v2
  state fork_state <<fork>>
    [*] --> fork_state
    fork_state --> State2
    fork_state --> State3

    state join_state <<join>>
    State2 --> join_state
    State3 --> join_state
    join_state --> State4
    State4 --> [*]

Class Diagrams¶

``` mermaid
classDiagram
  Person <|-- Student
  Person <|-- Professor
  Person : +String name
  Person : +String phoneNumber
  Person : +String emailAddress
  Person: +purchaseParkingPass()
  Address "1" <-- "0..1" Person:lives at
  class Student{
    +int studentNumber
    +int averageMark
    +isEligibleToEnrol()
    +getSeminarsTaken()
  }
  class Professor{
    +int salary
  }
  class Address{
    +String street
    +String city
    +String state
    +int postalCode
    +String country
    -validate()
    +outputAsLabel()  
  }
```

classDiagram
  Person <|-- Student
  Person <|-- Professor
  Person : +String name
  Person : +String phoneNumber
  Person : +String emailAddress
  Person: +purchaseParkingPass()
  Address "1" <-- "0..1" Person:lives at
  class Student{
    +int studentNumber
    +int averageMark
    +isEligibleToEnrol()
    +getSeminarsTaken()
  }
  class Professor{
    +int salary
  }
  class Address{
    +String street
    +String city
    +String state
    +int postalCode
    +String country
    -validate()
    +outputAsLabel()  
  }

Entity-Relationship Diagrams¶

An entity-relationship diagram is composed of entity types and specifies relationships that exist between entities. It describes inter-related things in a specific domain of knowledge:

``` mermaid
erDiagram
  CUSTOMER ||--o{ ORDER : places
  ORDER ||--|{ LINE-ITEM : contains
  LINE-ITEM {
    string name
    int pricePerUnit
  }
  CUSTOMER }|..|{ DELIVERY-ADDRESS : uses
```

erDiagram
  CUSTOMER ||--o{ ORDER : places
  ORDER ||--|{ LINE-ITEM : contains
  LINE-ITEM {
    string name
    int pricePerUnit
  }
  CUSTOMER }|..|{ DELIVERY-ADDRESS : uses