Examples of Dependency and Usage

Gallery
Tutorial
TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo
Section
08:01: The building Blocks of SysML
Topic level
BASIC
UML keywords
Dependency
Usage
Element
DirectedRelationship
SysML keywords
Block
Slide kind
SysML Block Definition Diagram (BDD)
The difference between Dependency and Usage in UML (and as available for general domain modelling in SysML) is notoriously vague:
UML-2.5.1: 'A Dependency is a Relationship that signifies that a single model Element or a set of model Elements requires other model Elements for their specification or implementation. This means that the complete semantics of the client Element(s) are either semantically or structurally dependent on the definition of the supplier Element(s).'
UML-2.5.1: 'A Usage is a Dependency in which the client Element requires the supplier Element (or set of Elements) for its full implementation or operation.'
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Don't fuss too much about which one you use where; try to choose a convention that makes sense for your model, and remember you can always convert between them easily in the tool. Also:
MagicDraw/Cameo: If you can't find Usage on a particular diagram just use a Dependency then the refactor context menu item.
But note carefully:
When dealing with required Interfaces you must use Usage (not Dependency) and it has dedicated "socket" notation.
Up next
Dependency vs Usage vs Association vs Connector
Notes
[TOOL, WORKAROUND]{SUGGESTED} MagicDraw/Cameo: If you can't find Usage on a particular diagram just use a Dependency then the refactor context menu item.
[WARNING] The difference between Dependency and Usage in UML is notoriously vague.
[ASSERTION, TIP]{STRICT} When dealing with required Interfaces you must use Usage (not Dependency) and it has dedicated "socket" notation.
Snippets (quotes/extracts)
  [UML-2.5.1] A Dependency is a Relationship that signifies that a single model Element or a set of model Elements requires other model Elements for their specification or implementation.
  [UML-2.5.1] This means that the complete semantics of the client Element(s) are either semantically or structurally dependent on the definition of the supplier Element(s).
  [UML-2.5.1] A Usage is a Dependency in which the client Element requires the supplier Element (or set of Elements) for its full implementation or operation.
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