More about UML

Unified Modeling Language

• UML is not a programming language. It’s a graphical notation for drawing diagrams to visualize object oriented systems.

• UML includes over a dozen different types of structural and behavioral diagrams.

• UML has been marketed for many contexts.

• Some problems (Wikipedia):

  • It has been treated, at times, as a design silver bullet, which leads to problems.

  • UML misuse includes overuse (designing every part of the system with it, which is unnecessary) and assuming that novices can design with it.

  • It is considered a large language, with many constructs. Some people feel that the size of UML hinders learning (and therefore, using) it.

“These diagrams should be a quick, useful communication tool. A support system for your brain, not the other way around!”

First iteration in planning can be paper or whiteboard Then there are benefits with digital tools

Building blocks

• Things

  • Structural

    • Class

    • Interface

    • collaboration

    • use case

    • component

    • node

  • Behavioral (dynamic)

    • interaction

    • state machine

  • Grouping

    • packaging

  • Annotational

    • Note

• Relationships

  • Dependency

  • association

  • generalization

  • realization

Diagrams

• Structure

  • Class

  • Component

  • Object

  • Composite structure

  • Package

  • Deployment

• Behavior

  • Use case

  • Activity

  • State machine

  • Interaction within/outside system

    • Sequence

    • Communication

    • Timing

    • Interaction overview

Class

A diagram that shows the system classes and relationships between them.

@startuml
 class01 <|-- class02
 class03 *-- class04
 class05 o-- class06

 class01- class03 : knows >
 class class01 {
    -var01 : Integer
    Time : Date
    #method01()
    +get_var01()
    {method}Without paranteces or Qualifiers
 }
 
 class class02 {
    -var02 : Float
    Time : Date
    #method01()
    +get_var02()
    {method}Without paranteces or Qualifiers
 }

@enduml

@startuml
class Car

Driver - Car : drives >
Car *- Wheel : have 4 >
Car -- Person : < owns
@enduml

Sequence

A diagram that shows the existence of Objects over time, and the Messages that pass between those Objects over time to carry out some behavior.

   
@startuml
user -> (use PlantUML)

note left of user
   Hello!   
end note
@enduml

@startuml
Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

Alice -> Bob: Another authentication Request
Alice <-- Bob: Another authentication Response
@enduml

@startuml
participant User

User -> A: DoWork
activate A

A -> B: << createRequest >>
activate B

B -> C: DoWork
activate C
C --> B: WorkDone
destroy C

B --> A: RequestCreated
deactivate B

A -> User: Done
deactivate A
@enduml

Activity

A flowchart that shows the process and its correlating decisions, including an algorithm or a business process.

@startuml

start

if (Graphviz installed?) then (yes)
  :process all\ndiagrams;
else (no)
  :process only
  __sequence__ and __activity__ diagrams;
endif

stop

@enduml

Syntax for algorithm flowchart

Start and stop

What’s this?

Computation

Input output

Choice

Direction of program flow Iterative or counting loop

Other

Use case

A diagram that shows relations between Actors and Use Cases.

@startuml
left to right direction
actor Guest as g
package Professional {
  actor Chef as c
  actor "Food Critic" as fc
}
package Restaurant {
  usecase "Eat Food" as UC1
  usecase "Pay for Food" as UC2
  usecase "Drink" as UC3
  usecase "Review" as UC4
}
fc --> UC4
g --> UC1
g --> UC2
g --> UC3
@enduml

Object

Object diagrams are derived from class diagrams so object diagrams are dependent upon class diagrams.

Object diagrams represent an instance of a class diagram. The basic concepts are similar for class diagrams and object diagrams. Object diagrams also represent the static view of a system but this static view is a snapshot of the system at a particular moment.

@startuml
object Object01
object Object02
object Object03
object Object04
object Object05
object Object06
object Object07
object Object08

Object01 <|-- Object02
Object03 *-- Object04
Object05 o-- "4" Object06
Object07 .. Object08 : some labels
@enduml

Component

A diagram that shows relations between various Components and Interfaces.

@startuml
package "Some Group" {
  HTTP - [First Component]
  [Another Component]
}

node "Other Groups" {
  FTP - [Second Component]
  [First Component] --> FTP
}

cloud {
  [Example 1]
}

Deployment

A diagram that shows relations between various Processors.

Deployment diagrams are used to visualize the topology of the physical components of a system, where the software components are deployed.

Deployment diagrams are used to describe the static deployment view of a system. Deployment diagrams consist of nodes and their relationships.

@startuml
node foo
foo --> bar : normal
foo --> bar1 #line:red;line.bold;text:red  : red bold
foo --> bar2 #green;line.dashed;text:green : green dashed 
foo --> bar3 #blue;line.dotted;text:blue   : blue dotted
@enduml

State

A diagram that shows States of a system or subsystem, Transitions between States, and the Events that cause the Transitions.

@startuml
scale 600 width

[*] -> State1
State1 --> State2 : Succeeded
State1 --> [*] : Aborted
State2 --> State3 : Succeeded
State2 --> [*] : Aborted
state State3 {
  state "Accumulate Enough Data\nLong State Name" as long1
  long1 : Just a test
  [*] --> long1
  long1 --> long1 : New Data
  long1 --> ProcessData : Enough Data
}
State3 --> State3 : Failed
State3 --> [*] : Succeeded / Save Result
State3 --> [*] : Aborted

@enduml

Timing

show timing constraints of a system in a given time frame

@startuml
robust "DNS Resolver" as DNS
robust "Web Browser" as WB
concise "Web User" as WU

@0
WU is Idle
WB is Idle
DNS is Idle

@+100
WU -> WB : URL
WU is Waiting
WB is Processing

@+200
WB is Waiting
WB -> DNS@+50 : Resolve URL

@+100
DNS is Processing

@+300
DNS is Idle
@enduml

Syntax

• https://plantuml.com/

Test yourself!

• PlantUML web server

• Look at the source files of this material.