19-06-2013, 01:02 PM
Unified Modeling Language
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Introducing the UML (Unified Modeling Language)
As the world becomes more complex, the computer-based systems that inhabit the world also must increase in complexity. They often involve multiple pieces of hardware and software, networked across great distances, linked to databases that contain mountains of information. If you want to make systems that deal with this, how do you get your hands around the complexity? The key is to organize the design process in a way that clients, analysts, programmers and other involved in system development can understand and agree on. The UML provides the organization. Consider this: Would you tell a building contractor that you want a 4 bedroom, 3 bath home, about 2000 square feet - Start building it! We'll hammer out the details as we go along? We all know this is ludicrous. But sadly, this method of development is all too common in the software industry. Just as you would work with an architect to design a blueprint that would diagram exactly how the house is to be built, you will work with us on an UML diagram that will document exactly how your custom software system will be built.
What is UML?'
The Unified Modeling Language (UML) is a standard language for specifying, visualizing, constructing, and documenting the artifacts of software systems, as well as for business modeling and other non-software systems. The UML represents a collection of best engineering practices that have proven successful in the modeling of large and complex systems. The UML is a very important part of developing object oriented software and the software development process. The UML uses mostly graphical notations to express the design of software projects. Using the UML helps project teams communicate, explore potential designs, and validate the architectural design of the software.
Types of UML Diagrams
Each UML diagram is designed to let developers and customers view a software system from a different perspective and in varying degrees of abstraction. UML diagrams commonly created in visual modeling tools include:
Use Case Diagram: This displays the relationship among actors and use cases. A use case is a description of a system's behavior from a user's standpoint. For system developers, this is a valuable tool: it's a tried-and-true technique for gathering system requirements from a user's point of view. That's important if the goal is to build a system that real people can use. In graphical representations of use cases a symbol for the actor is used. Use cases are a relatively easy UML diagram to draw, but this is a very simplified example. This example is only meant as an introduction to the UML and use cases.
Interaction Diagrams:
Sequence Diagram displays the time sequence of the objects participating in the interaction. This consists of the vertical dimension (time) and horizontal dimension (different objects). Class diagrams and object diagrams represent static information. In a functioning system, however, objects interact with one another, and these interactions occur over time. The UML sequence diagram shows the time-based dynamics of the interaction. Sequence diagrams demonstrate the behavior of objects in a use case by describing the objects and the messages they pass. the diagrams are read left to right and descending. The example below shows an object of class 1 start the behavior by sending a message to an object of class 2. Messages pass between the different objects until the object of class 1 receives the final message.