STUDY OF UML
General study of UML.
The heart of the problem solving is the construction of a model. The model abstracts the essential details of the underlying problem from its usually evomplicated real world. Several modeling tools are wrapped under the heading of the UML, which stands unified modeling language. The purpose of this course is to present important highlights of the UML.
At the center of the UML are its six kinds of modeling diagrams. Which are describing here
1. Use case diagram
2. Class diagram
3. Sequence diagram
4. Collaboration diagram
5. Activity diagram
6. State Diagram
7. Component diagram.
8. Object diagram
9. Deployment diagram
WHY IS UML IMPORTANT?
In the past decade the UML has emerged as the software development of blueprint language for analysis, designers and programmers alike. It is now paret of the software trade.
The UML is applicable to oo problem solving. Any one interested in learning UML must be familiar with the underlying tenet of oo problem solving, It all begins with the construction of a model. A model is a n abstraction of the underlying problem. The domain is the actual world from which the problem comes. Models consist of objects that interact by sending each other message. Think of an object as “alive” objects have things they know and things they can do. The values of an objects attributes determine its state.
Classes are the blueprints for objects. A class wraps attributes, behaviors in to a single distinct entity. Objects are instance of classes.
AN INTRODUCTON TO UML DIAGRAM:
The unifiers modeling language for specifying, constructing, visualizing and documenting the artifacts of a software intensive system., Analogous to the use of architectural blue prints in the construction industry. UML provides a common language for describing software models and it can be used in conjunction with a wide range of software life cycles and development processes.
The basic components of use case diagram are the Actor, the use case and the association.
An actor is the user of the system and is depicted using a stick figure. The role of the user is written beneath the icon. Actors are not limited to humans. If a system communicates with another application and expects input or delivers output then the application can also be considered as an actor.
A use case is functionality provided by the system, typically described as verb + object. Use cases are depicted with an ellipse. The name of the use case is written within the ellipse.
Associations are used to link actors with use cases and indicate that an actor. Participates in the use case in some form. Associations are depicted by a line connecting the actor and the use case.
The lifeline identifies the existence of the object overtime. The notation for lifetime is the vertical dotted line extending from an object.
Activations modeled as rectangular boxes on the lifetime indicate when the object is performing an action.
Messages modeled as horizontal arrows between activations, indicates the communications between the objects
When an activity state is completed processing moves to another activity state transitions are used to mark this movement. Transitions are modeled using arrows.
Swim lanes divide activities according to objects by arranging objects in column format and placing activities by that objects within that column. Objects are listed at the top of the columns, and vertical bars separate the columns to form the swim lanes.
The initial state marks the entry point and the initial activity state. The notation for the initial states is the same as in state chart diagrams, a solid circle. There can only be one initial state on a diagram.
Final states mark the end of the modeled workflow. Represented using a solid circle surrounded by another circle.
Activities often can be done in parallel. To split processing (fork), or to resume processing when multiple activities have been coupled (join), synchronization bars are used. These are modeled as solid rectangles, with multiple transactions going in and or out.
USE CASE DIAGRAM:
A use case is a set of scenarios that describing an interaction between a user and a system. A use case diagram displays the relationship among actors and use cases. The two main components of a use case diagram are use cases and actors. An actor is represents a user or another system that will interact with the system you are modeling.
A class diagram gives an overview of a system by showing its classes and the relationships among them. Class diagrams are static they display which interacts but not what happens when they do interact.
Class diagram has three kinds of relationships
Association: A relationship between instances of two classes.
1. Aggregation: An association in which one class belongs to a collection. In diagram order has a collection of order details,
2. Generalization: An inheritance link indicating one class is super class with the other. Payment is a super class of cash, cheque and credit.
Sequence diagram, document the interactions between classes to achieve a result, such as use case. The sequence diagram lists objects horizontally, and time vertically, and handles these messages overtime.
Collaboration diagrams are also interaction diagrams. They convey the information as sequence diagrams, but they focus on objects roles instead by the times that messages are sent., In a sequence diagrams object roles are the vertices and the messages are the connecting links. Last name are preceded by colons (:).
Activity diagram are used document workflows in a system, form the business level down to the operational level. In fact, the activity diagram is a variation of the state diagram where the “states” represent operations and the transitions represents the activities that happen when the operation is complete.
State diagrams are used to describe the behavior of a system. State diagrams describe all of the possible states of an object as events occur. Each diagram usually represents objects of a single class and track the different states of its objects through the system. State diagrams have very few elements. The basic elements are rounded boxes representing the state of the object and arrows indicting the transition to the next state. The activity section of the state symbol depicts what activities the object will be doing while it is in that state.
COMPONENT AND DEPLOYMENT DIAGRAMS:
A component is a code module, component diagrams are physical analogs of class diagrams. Deployment diagrams show the physical configurations of software and hardware.
The following deployment diagrams show the relationships among the software and hardware components involved in real estate transactions.
The physical hardware is made up of nodes. Each component belongs on a node. Components are shown as a rectangle with two tales at the upper left.
A detailed Study of UML was carried out