Artifact: System Use-Case Sequence Diagram
This artifact shows the time order of message exchanges between a use-case block and the environment (actors).
Domains: Systems Requirements
Purpose
To identify the ports and associated interfaces between the use-case block and associated actors.
Relationships
Description
Main Description

This artifact describes the time-ordered sequence of interactions between a system use case and its associated actors. In addition to the sent and received messages (service requests), the use-case lifeline shows the requested operations.

There will be multiple instances of this artifact. Initially, "black-box" sequence diagrams are created which evolve into "white-box" sequence diagrams that show the responsibilities of specific system elements.

Tailoring
Impact of not havingWithout this artifact, defining use-case block and actor block(s) ports and interfaces will be difficult and error-prone.
Representation OptionsThe Use-Case Black-Box Sequence Diagram is usually represented as a UML/SysML sequence diagram.