PlantUML: Working with state diagram

State diagram presents the order of states underwent by an object within the system.

State is defined using ‘state’ keyword.

 

state New

 

You can add colors to the state using #color notation.

state Running #green

 

You can give an alias to the state using ‘as’ keyword.

state "Suspend ready" as SR #FFFF77

 

You can connect one state to other state using -->

 

Ready --> Running : Schedule/dispatch

 

‘Schedule/dispatch’ message is displayed as array label.

 

helloworld.txt

@startuml

<style>
 document {
  BackGroundColor silver
}

</style>

left to right direction
skinparam roundCorner 50

title "Operating System Process states" 

state New #magenta
state Ready #palegreen
state Running #green
state "Suspend wait" as  SW #FFBA77
state "Wait / block" as WB #FFDF77
state "Suspend ready" as SR #FFFF77
state Termination #red

[*] --> New
New --> Ready

Ready --> Running : Schedule/dispatch
Running --> Ready : Priority/time elapse

Running --> Termination : completion
Running --> WB : I/O Request

WB --> Ready : I/O completion
WB --> SW : Suspend

SW --> WB : Resume
SW --> SR : Completed I/O, but still in suspend

SR --> Ready : Resume
Ready --> SR : Suspend

Termination --> [*]

@enduml

Above snippet generate below diagram.

Points to note

a.   [*] is used as starting and ending point in the state diagram.

b.   --> Connect two states

  

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