Mapping Flow of Interactions in the System

The sequence diagram can be created in the Model Structure below a behaviored classifier.

A sequence diagram is a graphic representation of an interaction and describes the exchange of messages between communication partners that are shown as lifelines.

The interaction can be read in two directions. The communication partners are formed as lifelines from left to right An imaginary time line runs from top to bottom; it shows the chronological order of single communication steps of the messages exchanged. The intervals do not means anything on this time axis and even the order the events occur in for messages only refers to its respective time line and not the others.

You can use combined fragments to show that a part of an interaction that certain rules apply for. These rules influence the selection and order of sent send and receive events and their frequency in the fragment. A combined fragment is described in more detail by an interaction operator and can consist of one or more areas, the interaction operands. If no interaction operator is specified, then the weak sequencing (seq.) operator always applies.