State diagram
PB007 Software Engineering I
Stanislav Chren
8. 11. 2021
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State diagram
State diagram models dynamic behaviour (lifecycle) of one reactive
object(class, use case, system, subsystem).
It consists of:
States
Transitions
Events
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Elements of state diagram
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States
State represents semantically important situation in an object. State of
the object is determined by its attribute values by connections to other
objects and ongoing activity.
State may include:
Entry/Exit actions
Internal actions/transitions
Internal activity
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Transitions
Transitions specify how the states of the object can change.
Transition consists of:
Events
Guard Conditions
Actions
Syntax: event[guard condition]/action
Semantics: At the occurence of the event, if the guard condition is
satisﬁed, perform the action and switch to the new state.
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Event
Event is a trigger, to which the object can respond by change of state or
by execution of an operation.
There are 4 types of events:
Call event - operation call on the given object.
Signal event - asynchronous sending and reception of a signal from
one object to another.
Change event - a boolean expression. The event occurs when the
evaluation of the expression changes from false to true.
Time event - the event occurs eithr at a speciﬁed time (when()) or
after speciﬁed duration (after())
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Events - example
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Composite states
Composite state is a state which contains inner states.
There are two types of composite states:
Simple composite states - they consist of single region. Often used
for capturing of ¨ınheritance”between the states.
Orthogonal composite states - they consist of at least two regions,
each containing a separate state machine. The inner state machines
are executed in parallel.
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Composite states - Example I
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Composite states - Example II
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Additional resources
http://www.uml-diagrams.org/state-machine-diagrams.html
http://mpavus.wz.cz/uml/uml-b-state-3-2-2.php
http://www.agilemodeling.com/artifacts/
stateMachineDiagram.htm
http://www.sparxsystems.com.au/resources/uml2_tutorial/
uml2_statediagram.html
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Tasks
Choose one reactive object (class instance) for modelling.
Make a list of all states that can be distinguished for the chosen
object and that are interesting to consider with respect to the
requirements and functions of the system.
Make a list of events that have impact on object states.
Based on the lists of states and events, construct a state diagram.
You can also try to use the composite states.
Submit the pdf report to homework vault(Seminar 09).
Deadline:
Saturday (Groups 03, 04)
Monday (Group 11)
Tuesday (Groups 06, 07)
Wednesday ([06:00 AM] Groups 08, 09)
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Rules for report submission
1 Submit the PDF report, not the VP source ﬁle and not an exported image.
2 PDF report must be created using the procedure shown on the seminars
including the report settings.
3 The name of the PDF report ﬁle should be lastname1-lastname2-lastname3
of the team members.
4 PDF report must contain all diagrams modelled until now.
5 PDF report must be uploaded to the homework vault by the speciﬁed
deadline.
6 PDF report must be uploaded to the correct homework vault. The name of
the homework vault is always speciﬁed on the slides.
7 Each team uploads only a single PDF report for the whole team.
8 Submitted diagrams must be clear and readable.
9 Submitted diagrams should not contain serious mistakes. At least, they
should not contain mistakes mentioned in the Catalogue of common
mistakes.
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VP report settings
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