ModellingClass T08

Conceptual Modelling – BehaviourFlow-Based Behavior

References:– Conceptual Modeling of Information Systems (Chapters 11 and 12)– A practical guide to SysML (chapter 8)– OMG Systems Modeling Language (OMG SysML) (Chapter 11)

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Modelação 2

ProgramT01-T02 – Module 1 - Introduction to Systems ModelingT03-T06 – Module 2 - Conceptual Modeling – Domain

T07-T11 – Module 3 - Conceptual Modeling – Behavior1. Overview2. Flow-Based Behavior3. Message Based Behavior4. Event Based Behavior5. Revision

T12-T15 – Module 4 - Ontology

T16-T19 – Module 5 - Conceptual Modeling – ArchitectureT20-T21 – Module 6 - Conceptual Modeling – MethodologiesT22-T23 – Module 7 - Ontology: Advanced

T24-T25 - Conceptual Modeling – Global Revisions; Exercises, …

SysMLUML

Behavior in UML and SyML

3Modelação

Flow-based behavior

Event-based behavior

Message-based behavior

Behavior – Activity Diagrams

4Modelação

Flow-based behavior

The behavioral schema

“The structural schema defines the types of the facts contained in the information base. These facts change over time, but they cannot change in any arbitrary way. Only some changes of the information base are permissible. These changes are called domain events. The definition of the domain event types is the most important part of the behavioral schema.”

Conceptual Modeling of Information Systems, page 247

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Systems and states…

(…) The state of a domain at any given point in time is the set of instances of the relevant entity and relationship types that exist in the domain at that time. (…) Most domains change over time, and therefore their state changes too. When the state of a domain changes, the information base must change accordingly. Of course, a domain cannot change in an arbitrary way. Only some changes are acceptable. The acceptable changes are called domain events. This concept (of a domain event) can be defined precisely in terms of a more basic concept, called a structural event (…)Conceptual Modeling of Information Systems, page 248

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Systems, states and events…

(…) We say that the state of the domain at time t changes if the domain state at that time, t, is different from the domain state at the previous time, t -1. Both states must satisfy all static constraints.

A state change is a set of one or more structural events. A structural event is an elementary change in the population of an entity or relationship type. The precise number and meaning of structural events depend on the conceptual modeling language used. Conceptual Modeling of Information Systems, page 248

In a more generic sense we can say that:

In a conceptual modeling project the precise number and meaning of structural events depend on the purpose of the project under way…

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Events as Activities…

“Activity modeling emphasizes the inputs, outputs, sequences, and conditions for coordinating other behaviors. It provides a flexible link to blocks owning those behaviors.”OMG Systems Modeling Language (OMG SysML) (Page 85)

“Activity is some work that is carried out; it might overlap several Use Cases or form only a part of one Use Case.”Enterprise Architecture User Guide

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Activities and actions…

An Activity organizes and specifies the participation of subordinate behaviors, such as sub-Activities or Actions, to reflect the control and data flow of a process. Activities are used in Activity diagrams for various modeling purposes, from procedural-type application development for system design, to business process modeling of organizational structures or work flow.Enterprise Architecture User Guide

In simple terms:–Activities are made of other Activities or of Actions.–Actions are Activities that are not decomposed.

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Activities and actions…

The following simple diagram of an Activity contains Action elements and includes input parameters and output parameters:Enterprise Architecture User Guide

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Activity Diagrams (UML)• An activity diagram is used to display the sequence of activities involving one or more

entities of the system. They show an workflow detailing the decision paths.• Activity diagrams are useful for business modeling where they are used for detailing the

processes involved in business activities.

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Activity Diagrams…

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Activity Elements and Connectors

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Graphical Nodes on Activity Diagrams

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Actions (atomic activities)

Activities

Refinement of Activity elements

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Enterprise Architect uses this symbol to

represent refinement

Graphical Nodes on Activity Diagrams

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Actions:InitialFinal

Actions:PreconditionsPostconditions

Graphical Nodes on Activity Diagrams

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Simple transitions

Transitions with object flow

Fork and Join

Decision

Merge

Graphical Nodes on Activity Diagrams

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Partition lanes can provide context…

… or it can be made clear in the activity

box itself

Activities and Partitions

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Context of the activity (a class of the domain)

• Activities always must have a context, represented by the system’s entity responsible for its execution (this points the specific entity for this activity; we assume the rest of the diagram belongs to the context of other entity).

• Activity diagrams can use partitions (lanes) to represent multiple contexts

More examples with partitions (lanes)

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Activities in UML and SysML…

• Main semantic differences are:– In UML Activities, control can only enable actions to start.– SysML extends control to support disabling of actions that are already executing.– A control value is an input or output of a control operator, which is how control

acts as data. A control operator can represent a complex logical operation that transforms its inputs to produce an output that controls other actions

– See section 8.6 of “A practical guide to SysML” for more details…

• For all the rest, Activities are quite the same in UML and SysML…

Modelação 21

An example of an Activity Diagram in SysML

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Aggregating activities in SysMLActivities can be aggregated in block diagrams to represent all the activities of a specific context

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