What is UML?

1. What is UML? • The Unified Modeling Language (UML) is a standard way to specify, construct, and document systems that use object-oriented code such as Java or C++. As with any language, the UML has its own notation and syntax. Its notation comprises a set of specialized shapes for constructing different kinds of software diagrams. Each shape has a particular meaning, and the UML syntax dictates how the shapes can be combined. • Although many major object-oriented analysis and design methods influenced the development of the UML, it is derived primarily from three notations: Booch OOD (Object-Oriented Design), Rumbaugh OMT (Object Modeling Technique), and Jacobson OOSE (Object-Oriented Software Engineering). • In 1997, the Object Management Group (OMG) made the UML a standard modeling language for object-oriented applications.   The OMG includes more than 800 software vendors, developers, and users who seek a common architectural framework for object-oriented programming. • The OMG's Unified Modeling Language™ (UML™) uses twelve standard diagram types . 

2. Modeling • Modeling is the designing of software applications before coding. • A model plays the analogous role in software development that blueprints and other plans (site maps, elevations, physical models) play in the building of a skyscraper. • Using a model, those responsible for a software development project's success can assure themselves that business functionality is complete and correct, end-user needs are met, and program design supports requirements for scalability, robustness, security, extendibility, and other characteristics, before implementation in code renders changes difficult and expensive to make. • Surveys show that large software projects have a huge probability of failure - in fact, it's more likely that a large software application will fail to meet all of its requirements on time and on budget than that it will succeed. If you're running one of these projects, you need to do all you can to increase the odds for success, and modeling is the only way to visualize your design and check it against requirements before your crew starts to code. 

3. What can you Model with UML? UML defines twelve types of diagrams, divided into three categories • Four diagram types represent static application structure: • Class Diagram • Object Diagram • Component Diagram • Deployment Diagram • Five represent different aspects of dynamic behavior • Use Case Diagram • Sequence Diagram • Activity Diagram • Collaboration Diagram • Statechart Diagram • Three represent ways you can organize and manage your application modules • Packages • Subsystems • Model

4. Use Case Diagrams • A use case diagramshows a set of use cases and actors (a special kind of class) and their relationships. Use case diagrams address the static use case view of a system. These diagrams are especially important in organizing and modeling the behaviors of a system. Source: UML Multimedia Cybel Classroom (All diagram examples)

5. Class Diagrams • A class diagram shows a set of classes, interfaces, and collaborations and their relationships. These diagrams are the most common diagram found in modeling object-oriented systems. Class diagrams address the static design view of a system.

6. State Diagrams (statechart) • A statechart diagramshows a state machine, consisting of states, transitions, events, and activities. Statechart diagrams address the dynamic view of a system. They are especially important in modeling the behavior of an interface, class, or collaboration and emphasize the event-ordered behavior of an object, which is especially useful in modeling reactive systems.

7. :Name Sequence Diagram - Objects • A life line illustrates what is happening to an object in a chronological fashion. Object Life line Activation

8. Sequence Diagrams and Collaboration Diagrams • Both sequence diagrams and collaboration diagrams are kinds of interaction diagrams. An interaction diagram shows an interaction, consisting of a set of objects and their relationships, including the messages that may be dispatched among them. Interaction diagrams address the dynamic view of a system. A sequence diagram is an interaction diagram that emphasizes the time-ordering of messages; a collaboration diagram is an interaction diagram that emphasizes the structural organization of the objects that send and receive messages. Sequence diagrams and collaboration diagrams are isomorphic, meaning that you can take one and transform it into the other.

9. Activity Diagram • An activity diagramis a special kind of a statechart diagram that shows the flow from activity to activity within a system. Activity diagrams address the dynamic view of a system. They are especially important in modeling the function of a system and emphasize the flow of control among objects

10. Component Diagram • A component diagramshows the organizations and dependencies among a set of components. Component diagrams address the static implementation view of a system. They are related to class diagrams in that a component typically maps to one or more classes, interfaces, or collaborations

11. Deployment Diagram • A deployment diagramshows the configuration of run-time processing nodes and the components that live on them. Deployment diagrams address the static deployment view of an architecture. They are related to component diagrams in that a node typically encloses one or more components.