Glossary

This is a glossary of OSA terms. Each entry has a brief definition, a link to the main defining page, and links to related terms. A list of symbols used in the graphical representation of OSA models is in the symbolary.

Access Interaction
An access interaction is a shorthand for a bidirectional interaction with the system being modeled. It is used to obtain information about objects, usually regarding relationships and related objects.

Action
An action is a process in states or a procedure in transitions that allow states or transitions to do some processes.

Add Interaction
An add interaction adds an object that already exists in the model to an object class. See also the create interaction.

Aggregation
Aggregation models the is subpart of relationship set. It is used when one object class is made up of one or more component object classes.

Association
Association models the is member of relationship set. It is used when one object class is a set of objects from another object class.

Bidirectional Interaction
A bidirectional interaction is used when there are two one way interactions that are so closely related that they can be treated as being the same interaction.

Cardinality Constraint
See Object-class Cardinality Constraint.

Condition
A condition is a logical statement about the state of the system, the state or existence of an object, or the existence of relationships between objects.

Condition-Based Trigger
See Condition.

Constraint
A constraint restricts possible occurences or allowable combinations in relationship sets, interactions, object classes, etc. There are Co-occurrence Constraints, Object-class Cardinality Constraints, Participation Constraints, and General Constraints.

Continuous Interaction
A continuous interaction is one where the origin object is continuously sending information to the destination object.

Co-occurrence Constraint
A co-occurrence constraint specifies the minimum and maximum number of times an object or combination of objects can co-occur in the relationships of a relationship set with another object or combination of objects.
See also Constraint, Object-class Cardinality Constraint, and Participation Constraint.

Create Interaction
A create interaction creates a new obect in the model. See also the add interaction.

Destroy Interaction
A destroy interaction causes an existing object to cease to exist as far as the analysis model is concerned.

Event
An event is a change within the system, including the creation or deletion of objects or relationships, the starting or stopping of an activity, and the reception of messages.

Event-Based Trigger
See Event.

Exception
An exception is a system event or condition which is not part of normal system behavior. For example, a printer running out of paper during a print job is an exception.

Final Transition
A final tansition is a transition with no subsequent state conjunction.

General Constraint
A general constraint specifies any information constraining relationship set which cannot be specified as co-occurrence constraint, object-class cardinality constraint, or participation constraint.

Generalization
A generalization is an object class which is a superset of another object class (or classes). Generalization models the is a relationship set since members of the specialization class (or classes) are always members of the generalization class. This means that members of the specialization class have all of the same properties of the generalization class including relationships with other objects as well as behaviour. Therefore, specialization plays an important role in the ORM, OBM, and the OIM.
See also Specialization.

High-Level Object Class
A high-level object class is an object class that contains other object classes, relationship sets, constraint, and notes.

High-Level Interaction
A high-level interaction is an interaction that is an abstraction of lower level interactions, objects, object classes, general interactions constraints, and notes.

High-Level Object Class
A high-level object class is an object class that contains other object classes, relationship sets, constraints, and notes.

High-Level Relationship Set
A high-level relationship set is a relationship set that is an abstraction containing other relationship sets, object classes, constraint, and notes.

High-Level State
A high-level state is a state that is an abstraction of lower level states, transitions, constraints, and notes.

High-Level Transition
A high-level transition is a transition that is an abstraction of lower level transitions, states, constraints, and notes combined.

High-Level View
A high-level view is the view of an interaction with the "internal" details omitted.

Homonym
When two object classes appear in the model with the same name, these are considered the same object class.
See also Synonym.

Initial Transition
An initial transition is a transition that has no prior state conjunction on it.

Interaction
An interaction is any inter-object communication. It can be thought of as a message between the participating objects.

Intersection Constraint
An intersection constraint is used when a specialization object class has more than one generalization object class and shows that the specialization object class is the intersection of the generalization object classes. In other words, any object in all of the generalizations is also in the specialization.

Lexical Object Class
A lexical object class is a class whose members have a one-to-one mapping to their representation.

Membership Condition
A membership condition is a constraint imposed on the object class by the ORM. To be a member of an object class, an object must satisfy the membership conditions for that class. Over time, an object may be a member of different object classes. This is referred to as class migration.

Modify Interaction
A modify interaction is an interaction that update some data in object.

Mutual Exclusion Constraint
The mutual exclusion constraint indicates that the specialization object classes are pairwise disjoint. In other words, no object can be a member of more than one specialization object class.

Notes
Notes are explanatory text added to diagrams. They have no semantic significance to the model.

Object
An object is any unique thing such as a person, place, or any physical or conceptual thing.

Object Class
An object class is a set of objects that have shared properties.

Object-Class Cardinality Constraint
An object-class cardinality constraint restricts the number of objects in an object class.
See also Constraint, Co-occurrence Constraint, and Participation Constraint.

Participation Constraint
A participation constraint defines the number of times an object in an object class can participate in a connected relationship set.
See also Constraint, Co-occurrence Constraint, and Object-Class Cardinality Constraint.

Partition Constraint
The partition constraint indicates that every object in a generalization object class must also be a member of at least one of the specialization object classes, and that the specialization object classes are pairwise disjoint.

Path Marker
A path marker is used to apply a real-time constraint to a part of a state net. They are shown on the diagram as identifiers in braces ("{}") placed along directed arrows.

Prior State
A prior state is a state which preceeds a transition. A state may be a prior state of some transitions and a subsequent state of others.
See also Subsequent State.

Prior State Conjunction
A transition may require more than one state to be on before it begins. The set of prior states which must be on is a prior state conjunction.
See also Subsequent State Conjunction.

Real-Time Constraint
A real-time constraint is a maximum time in which something should be completed. Real-time constraints are shown in diagrams inside braces ("{}") and may be applied to states, triggers, actions, entire transitions, or state nets (using path markers).

Relational Object Class
An object class which contains relationship sets. Shown on diagrams by drawing an object class rectangle around a relationship set and all participating object classes.

Relationship
A relationship establishes a logical connection among objects.

Relationship Set
A relationship set is a set of similar relationships.

Remove Interaction
Remove deletes an object from an object class, but not necessarily from the analysis model.

Role
A role is a shorthand way of expressing a specialization.

Specialization
A specialization is an object class which is a subset of another object class (or classes). Specialization models the is a relationship set since members of the specialization class (or classes) are always members of the generalization class. This means that members of the specialization class have all of the same properties of the generalization class including relationships with other objects as well as behaviour. Therefore, specialization plays an important role in the ORM, OBM, and the OIM.
See also Generalization.

Synonym
Synonyms are multiple names for a single object class. These are shown in the object class rectangle, separated by a vertical bar ("|").

State
A state is the status, phase, situation, or activity of an object at any given point in time.

State Net
A state net is the representation of the states of an object and the flow of control within an object or between objects.

Subsequent State
A subsequent state is a state which follows a transition. A state may be a prior state of some transitions and a subsequent state of others.
See also Prior State.

Subsequent State Conjunction
A transition may turn on more than one state when it finishes. The set of subsequent states which are turned on is a subsequent state conjunction.
See also Prior State Conjunction.

Thread
A thread is a flow of control or execution within an object's behavior.

Time-constrained Interaction
A time-constrained interaction is a time-critical interaction that must take place in a specified finite amount of time.

Transition
A transition is how an object changes state. Transitions consist of a trigger description, an action description, and an optional transition identifier.

Trigger
A trigger is a combination of events and conditions which may activate a state transition.

Union Constraint
The union constraint indicates that every object in a generalization object class must also be a member of at least one of the specialization object classes.

Go to the OSA Tutorial
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Created Tue Sep 13 12:41:11 1994 ...
Updated Wed Nov 23 13:38:19 1994
by Paul E. Black (black@lal.cs.byu.edu)