Glossary

Syntropy Glossary

This glossary defines terms used in the Syntropy method.

Abstract type: An object type such that all objects conforming to it must also conform to one of its sub-types
Active object: An object with its own thread of control
Aggregation: A property of an association representing life-time containment. The life-times of the aggregated objects are contained within the life-time of the aggregating object
Association: A generic description of a related set of links between objects of two types
Association property: A property that belongs to an association rather than an object type
Class: A template defining the implementation of a set of object features
Concept domain: A domain within a specification or implementation model that contains object types corresponding directly to object types found in the essential model
Conformance: When features offered by an object satisfy all the expectations defined by an object type
Consequence: A textual statement of the effects of an event or message on an object
Constraint: A restriction, typically on an association
Creation operation: An operation implicitly invoked on object creation that initialises an object
Derived association: An association whose members can be determined from one or more other associations
Detected event: An event that causes the state of the software system to change
Domain: A collection of related object types that together provide a coherent unit. The domains partition the object types
Encapsulation: Localisation of knowledge within an object
Essential model: A model constructed to describe the structure and behaviour of a real or imagined situation in the world, without reference to the role software might play in its creation
Event: An occurrence that carries information. Events are defined as an instantaneous broadcast of information to all interested objects
Event list: A list in the textual part of a specification or implementation model statechart that indicates all the event types of interest to that object type
Event table: A table listing events, parameters, pre-conditions and consequences
Event type: The signature of an event: its name and parameter types
Exception: An indication in software that a fault has occurred
Exclusive contract: A contract between two objects such that one is the only client of the other
Filter: A statically determinable logical predicate in an event list that defines the set of objects interested in any particular event occurrence
Finalisation: The transition of an object into a condition where it is no longer part of the model
Generated event: An event in a specification model generated by an object
Guard: A logical predicate that limits the availability of a transition in a statechart
Implementation model: A model of a domain constructed to describe the interfaces of objects, their relationships and their interaction (in terms of message sequences)
Infrastructure domain: A domain that provides software-related services to other domains
Inheritance: The ability of a sub-type automatically to include features of its super-types
Initial object: The object that forms the root of an instance of a model; the single instance of the initial type
Initial object configuration: The set of objects, including the initial object, that exist at the moment an instance of a model is created
Initial type: The type of the initial object
Interaction domain: A domain containing types describing objects that connect objects in concept domains to the environment
Internal event: An event in a specification model that is both generated and detected
Invariant: A logical predicate that limits properties or associations
Link: A connection between two objects, in accordance with an association; an instance of an association
Link type: An object type that is related to an association
Mechanism: An example object interaction with messages
Message: A synchronous request made by one object of another, taking a measurable time to process
Message sequence diagram: A diagram that shows a mechanism as a time-line
Model: A description of the structure and behaviour of a set of objects, portrayed through a number of views, built to illustrate a particular perspective: essential, specification or implementation
Multiple association: An association end that yields a set of objects
Multiplicity: The number of objects permitted to form the result of navigating an association
Name space: The set of names that belong to a type, especially its property names and role names
Navigation expression: An expression that traverses associations to yield one or more objects or values, starting from a particular object
nil: The value yielded by unset properties or an empty optional association
Non-exclusive contract: A contract between two objects such that one is just one of many clients of the other
Object: A unique grouping of information that conforms to one or more object types
Object diagram: A diagram depicting objects and their links
Object type: A named set of features to be provided by one or more objects
Observer: An operation that will not cause a change in state of the system
Operation: A named unit of processing belonging to an object type in an implementation model, invoked by a message
Optional association: An association end that yields zero or one objects
Orthogonal state machine: The name given to a state machine when the statechart comprises two or more machines
Overriding: The redefinition by a sub-type of a feature inherited from a super-type
Parameterised property: An object property whose value depends on one or more parameters supplied when the property is evaluated
Parameterised type: An object type that uses a value type denoted only by a place-holder; the place-holder to be substituted by a value type when the object type is used
Post-condition: A logical expression used in statecharts that indicates the state of an object after an event or message has been detected/received
Pre-condition: A textual statement or logical predicate that indicates conditions which must hold for an event or message to be detected/received
Property: A named value owned by an object
Qualified association: A multiple association whose membership is partitioned by the value of a qualifier
Qualifier: A function signature used to select association members in a qualified association
Recursive association: An association where the source and the destination are the same object type
Relaxed section: The final section of an updater; other updaters of the same object can execute concurrently in other threads
Role name: The name attached to an association end to indicate its purpose
Secured section: The first section of an updater; it must execute in mutual exclusion with other secured sections and observers
self: The name given to the anonymous object used in a navigation expression to identify the starting point of the navigation; the anonymous object assumed to have detected the event or received the message in a statechart
Specification model: A model constructed to describe abstractly the structure and stimulus-response behaviour of a software system, assuming infinite resources and processing power
State view: A view of a model describing how its state changes over time
Statechart: A form of finite state machine used to describe the dynamic behaviour of objects
Sub-type: An object type such that objects conforming to it also conform to one or more other types (its super-type)
Super-type: An object type that has sub-types
Synchronisation expression: A logical predicate that controls the availability of operations in a non-exclusive contract
Synchronising type: An object type containing synchronisation expressions
Thread: A control path through the software
Type view: A view of a model describing its object types and their relationships
Updater: An operation that may cause a change in state of the system
Value: An immutable quantity whose identity is itself
Value type: A type whose members are values
View: A diagram describing one aspect of a model
Viewpoint: A subset of the features of an object type defined for use by a particular kind of client
Visibility: The ability to navigate an association in a particular direction

Comments, corrections to jdaniels@cix.co.uk