Specification and Description Language (SDL)

This finite state machine diagram example was redesigned from the Wikimedia Commons file: SdlStateMachine.png. [commons.wikimedia.org/ wiki/ File:SdlStateMachine.png]
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. [creativecommons.org/ licenses/ by-sa/ 3.0/ deed.en]
"Behavior.
Each process agent is a state machine that contributes to the action carried out by the system. A message stimulus coming from the environment or from another agent to an agent is called a signal. Signals received by a process agent are first placed in a queue (the input port). When the state machine is waiting in a state, if the first signal in the input port is enabled for that state it starts a transition leading to another state. Transitions can output signals to other agents or to the environment. A process agent is allowed to contain procedure types so that the same actions can be invoked from different places. It is also allowed to call a remote procedure type to invoke a procedure in another agent (or even another system) and wait for a response." [Specification and Description Language. Wikipedia]
The example "SDL diagram - State Machine" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Specification and Description Language (SDL) solution from the Engineering area of ConceptDraw Solution Park.