Purpose

Depicts the system architecture from a logical point of view.

Example:

Description

Contains a representation of the logical structure of a system architecture, consisting of components (whose contents are to be defined) and elements (whose contents are, it has been decided, not to be defined). Both components and elements can be shown as rectangular, triangular and circular symbols, to follow an optional project-specific convention.
Components and equipments are connected by bi-directional data connections, representing system buses or point-to-point connections. Two forms of connections are provided, data and signal (primarily for the conveyance of control signals). For low volume connections (connections either conveying few pieces of data and/or a limited number of data packets), the data or signal link symbols are provided, shown as thin lines. For connections conveying large and/or complex data, the channel symbols are provided, shown as thick lines.
All components are defined by PSpecs and can be decomposed into a lower-level diagram:

• Another AID

• A Data Flow Diagram (DFD)

• A Behaviour Diagram (BD), also called an extended Function Flow Block Diagram (eFFBD)

• An IDEF0 diagram

• A UML Use Case Diagram (UCD)

Strengths

Allow a clear representation of parallel, sequential and iterative behaviour, including synchronisation of parallel execution threads.

Weaknesses

Limited to the contents of a single class, and inherently non-hierarchical, with no opportunities for re-use of functionality other than complex class inheritance.

Recommended Uses

Functionality of classes, if the classes are deemed to be sufficiently complex.

Diagram Conversions

None.

Characteristics
APPEARS IN MODELS: Implementation
NUMBERING: Same as the class
HIERARCHICAL: No

Linkage:

Symbols

Symbol	Name	Description	Definition	Expansion
	Comment	Makes a note anywhere in the diagram. Are always surrounded by * characters.	None	None
	Boundary point	A connection point for the initial transition to enter the initial state.	None	None
	Terminator	Represents external system or environment to this system	Terminator Description	None
	Picture	Allows you to choose the location of a GIF or JPEG image to be displayed as a diagram symbol or to be embedded in an existing diagram symbol.	None	None
	Circular component	Represents a system item categorised as a component (optional symbology)	PSpec	AID DFD BD UCD IDF
	Rectangular component	Represents a system item categorised as a component (optional symbology)	PSpec	AID DFD BD UCD IDF
	Triangular component	Represents a system item categorised as a component (optional symbology)	PSpec	AID DFD BD UCD IDF
	Circular element	Represents a system item categorised as an element (optional symbology)	None	None
	Rectangular element	Represents a system item categorised as an element (optional symbology)	None	None
	Triangular element	Represents a system item categorised as an element (optional symbology)	None	None
	Data link	Represents low volume connection for data link	Data Definition	None
	Data channel	Represents high volume channel connection for complex or large data link	Data Definition	None
	Signal link	Represents low volume connection for signal link	Data Definition	None
	Signal channel	Represents high volume channel connection for complex or large signal link	Data Definition	None

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