Requirement extensions (SysML item)
The SysML profile includes the following non-normative Requirement Extensions:
Design Constraint
Extended Requirement
Functional Requirement
Interface Requirement
Performance Requirement
Physical RequirementCreate a Requirement Extension through a Modeler explorer pane or a diagram:
• In a Modeler pane, right-click the Model or Package that is to own the Requirement, point to New, point to SysML, point to Requirements, and then click the appropriate command for the Requirement Extension you want to create.
• In a Modeler pane, right-click the Requirement or Requirement Extension that is to own the Requirement, point to New, point to SysML, and then click the appropriate command for the Requirement Extension you want to create.
• On a diagram, click the button for the Requirement Extension you want to create, and then click in free space on the diagram.
For more information about using Requirement Extensions, see the topics for Requirements in the Modeler Help: Requirement Extensions are subtypes of the Requirement item type and can be used in mostly the same way as Requirements in the model except for the following differences:
• Most of the Requirement Extensions have restrictions as to which items they can be linked to using a Satisfy relationship.
• The Requirement Extensions have the following additional SysML Properties: Risk, Source and VerifyMethod.
Design Constraint
A Design Constraint can be satisfied only by Blocks or Block Properties of type part.
Extended Requirement
A mix-in stereotype that contains generally useful attributes for requirements.
Functional Requirement
A Functional Requirement can be satisfied only by Activities, Operations and State Machines.
Interface Requirement
An Interface Requirement can be satisfied only by
Binding Connectors, Connectors, Constraint Properties, Flow Ports, Full Ports, Item Flows, Proxy Ports and Standard Ports.
Performance Requirement
A Performance Requirement can be satisfied only by Block Properties of type value.
Physical Requirement
A Physical Requirement can be satisfied only by Blocks, Block Properties of type part, Flow Ports, Full Ports, Interface Blocks, Proxy Ports and Standard Ports.
The following sections provide information about how the Requirement Extensions are used in the model. For more information about a SysML diagram or item - click it.
Owned by
Model (UML item)
Package (UML item)
Owns
Allocate - the Allocate is owned jointly by the Requirement Extension and the associated item. The access permissions you have to an Allocate are determined by the access permissions you have to the item that is allocated from - you require write access to both items to create or delete an Allocate.
Derive Reqt - the Derive Reqt relationship is owned jointly by the two Requirements it links. The access permissions you have to a Derive Reqt relationship are determined by the access permissions you have to the derived Requirement.
Shown on these diagrams
Requirement Extensions can be shown on most UML and SysML diagrams.
SysML Properties
The Requirement Extensions have all the SysML properties of a Requirement and these additional properties:
• risk - specifies the risk, either High (unacceptable level of risk), Medium (acceptable level of risk) or Low (minimal level of risk).
• source - specifies the source of the Requirement Extension.
• verifyMethod - specifies the method for verification, either Analysis, Demonstration, Inspection or Test.
The Requirement Extension inherits these properties from a Requirement:
allocatedFrom - lists source items that are linked through Allocate relationships (on Allocated tab when item is allocated).
allocatedTo - lists target items that are linked through Allocate relationships (on Allocated tab when item is allocated).
derived - lists source items that are linked through Derive Reqt relationships.
derivedFrom - lists target items that are linked through Derive Reqt relationships.
id# - A unique id for the Requirement Extension, which may be an id assigned to the Requirement Extension by an external requirements management tool.
isDeletedInRequirementTool - specifies that the Requirement Extension's associated item in PTC Integrity Lifecycle Manager or DOORS has been deleted (used by Integration for PTC Integrity Lifecycle Manager and Integration for IBM Rational DOORS).
isExternallyManaged - can be used to specify that the Requirement Extension is managed by an external requirements management tool.
isInRequirementTool - specifies that the Requirement Extension is associated with an item in PTC Integrity Lifecycle Manager or DOORS (used by Integration for PTC Integrity Lifecycle Manager and Integration for IBM Rational DOORS).
master - lists target items that are linked through Copy relationships.
parentRequirement - lists the parent Requirement or Requirement Extension, if there is one.
problem - lists child Problems.
rationale - lists child Rationales.
refinedBy - lists source items that are linked through Refine relationships.
refines - lists target items that are linked through Refine relationships.
satisfiedBy - lists source items that are linked through Satisfy relationships.
satisfies - lists target items that are linked through Satisfy relationships.
slave - lists target items that are linked through Copy relationships.
subRequirement - lists child Requirements and Requirement Extensions.
synchronizationStatus - can be used to specify the status of a Requirement Extension when managed by an external requirements management tool.
tracesFrom - lists source items that are linked through Trace relationships.
tracesTo - lists target items that are linked through Trace relationships.
txt - derived from the Description property of the Requirement Extension, but can be inherited from a master Requirement or Requirement Extension through the Copy relationship.
verifiedBy - lists source items that are linked through Verify relationships.
verifies - lists target items that are linked through Verify relationships.