The Unified Modeling Language (UML) was created to forge a common, semantically and syntactically rich visual modeling language for the architecture, design and implementation of complex software systems both structurally and behaviorally. UML has applications beyond software development, such as process flow in manufacturing.

It is a graphic language to visualize, specify, construct and document a system. UML offers a standard for describing a system (model), including conceptual aspects such as processes, system functions, and specific aspects such as expressions of programming languages, database schemas …

UML is not programming, only is diagrammed the reality of a use in a requirement.

UML has several types of diagrams, which show different aspects of the entities represented.

UML uses elements and associates them in different ways to form diagrams that represent static or structural aspects of a system, and behavior diagrams that capture the dynamic aspects of a system.

UML structural diagrams:

• Class diagram.
• Components diagram.
• Structure diagram.
• Implementation diagram.
• Object diagram.
• Package diagram.

UML behavioral diagrams:

• Activity diagram.
• Communication diagram.
• Interaction diagram.
• Sequence diagram.
• State machine diagram.
• Timing diagram.
• Use case diagram.

Is the main diagram used in TAST application. Below, we give a brief explanation of what a sequence diagram is, and show some examples.

A sequence diagram shows the interaction of a set of objects in an application over time, and is modeled for each use case. Describe how a group of objects works together and in what order they do it.

The sequence diagram contains details of scenario implementation, including the objects that are used to implement the scenario and messages exchanged between the objects.

In the sequence diagram can be used branches, conditions and loops.

Below, some examples of sequence diagrams: