UML

What is a UML state diagram? A state diagram (called in the UML 1.x specification) is a diagram showing a state machine and is called a state machine diagram in UML 2.x. The so-called state machine is a behavior that describes the various states and state transitions of an object in its life cycle. A state diagram is one of the 14 UML diagrams used for modeling in UML 2.0.   It defines the different states of an object during its lifecycle, which change in response to events. State diagrams are useful for…continue reading →

What is UML? UML is a standard notation for object-oriented methods, which was created by unifying Object Modeling Techniques. It is used for analysis, design and deployment of systems. The Unified Modeling Language was designed to respond to the needs of businesses to automate the production of software, improve quality and reduce cost and time-to-market. It also provides a formal basis for understanding the modeling language. Why UML? Large enterprise applications must be structured in a way that enables scalability, security, and robust execution under stressful conditions. A well-designed architecture enables code reuse,…continue reading →

UML Sequence Diagrams are interaction diagrams that detail how operations are carried out. They capture the interaction between objects in the context of a collaboration. Sequence Diagrams are time focus and they show the order of the interaction visually by using the vertical axis of the diagram to represent time what messages are sent and when.

In UML, relationships are connections between model elements. Use cases are also connected to each other in different kinds of relationships. The relationship between two use cases basically models the dependencies between two use cases. By reusing existing use cases using different types of relationships, the overall effort required to develop the system is reduced. Use case diagrams show use cases, actors, and the relationships between them. For example, the relationship between an actor and a use case illustrates that the actor can use a certain functionality of the business system.

Use case relationships model the dependencies between use cases in the interaction model of the system. Although, independent use cases can adequately represent simpler systems. However, in order to represent complex or large systems, we may need to construct complex use cases with the help of dependencies between use cases. Establishing relationships between use cases allows reuse of those use cases that need to be defined over and over again, which reduces developer effort.

Packages in the Unified Modeling Language are used to group elements and provide namespaces for the grouped elements. A package can contain other packages, thus providing a hierarchical organization of packages. Almost all UML elements can be grouped into packages. Thus, classes, objects, use cases, components, nodes, node instances, etc. can be organized into packages, thus making the organization of the myriad elements contained in a real-world UML model manageable.

Multiplicity in class diagram should be indicated at each end of the association. This specifies the minimum and maximum number of instances that can be linked. For example, a car has 3 or 4 wheels, but each wheel belongs to exactly one car. Place multiplicity notations near the ends of an association. These symbols indicate the number of instances of one class linked to one instance of the other class.

There are six main types of relationships between classes: inheritance , realization / implementation , composition , aggregation , association, and dependency .