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OOAD Tutorial in PDF - Learn Object Oriented Analysis and Design in simple and easy steps starting from basic to advanced concepts with examples including. Describing how the objects interact. The common models used in OOA are use cases and object models. 1. OOAD ─ Object-Oriented Paradigm. OOAD - OBJECT MODEL. The object model visualizes the elements in a software application in terms of objects. In this chapter, we will look into the basic.
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Kindly pay an amount of USD before you download this wonderful tutorial in PDF version. We have put lot more effort to bring it to you. DOWNLOAD. target code efficient and optimized in terms of time and space. this tutorial, please notify us Selenium Tutorial (PDF Version) - TutorialsPoint. UML Tutorial - custom-speeches.com - Download as PDF File .pdf), Text File .txt) or read online. UML is a standard language for specifying, visualizing.
As an example, consider a design in Java that uses a JFrameto display the information. Assume the NextGen application has a window that displays sale information and captures cashier operations. Using the Controller pattern, Figure illustrates an acceptable relationship between the JFrameand the controller and other objects in a portion of the POS system with simplifications. It did not get involved in processing the operation or deciding how to handle it; the window only delegated it to another layer.
Assigning the responsibility for system operations to objects in the application or domain layer by using the Controller pattern rather than the UI layer can increase reuse potential. If a UI layer object like the SaleJFrame handles a system operation that represents part of a business process, then business process logic would be contained in an interface for example, window - like object; the opportunity for reuse of the business logic then diminishes because of its coupling to a particular interface and application.
Consequently, the design in Figure is undesirable. Placing system operation responsibility in a domain object controller makes it easier to reuse the program logic supporting the associated business process in future applications.
It also makes it easier to unplug the UI layer and use a different UI framework or technology, or to run the system in an offline "batch" mode. Message Handling Systems and the Command Pattern Some applications are message - handling systems or servers that receive requests from other processes.
A telecommunications switch is a common example. In such systems, the design of the interface and controller is somewhat different. Desirable coupling of UI layer to domain layer statedPatterns Command : - In a message - handling system, each message may be represented and handled by a separate Command object [GHJV95]. Placing domain logic in the domain layer rather than the presentation layer is part of the Layers pattern.
Less desirable coupling of interface layer to domain layer High Cohesion Problem How to keep objects focused, understandable, and manageable, and as a side effect, support Low Coupling? In terms of object design, cohesion or more specifically, functional cohesion is a measure of how strongly related and focused the responsibilities of an element are.
An element with highly related responsibilities that does not do a tremendous amount of work has high cohesion. These elements include classes, subsystems, and so on.
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Solution Assign a responsibility so that cohesion remains high. Use this to evaluate alternatives. A class with low cohesion does many unrelated things or does too much work. Such classes are undesirable; ti:ey suffer from the following problems: hard to comprehend hard to maintain delicate; constantly affected by change Low cohesion classes often represent a very "large grain" of abstraction or have taken on responsibilities that should have been delegated to other objects.
ExampleLet's take another look at the example problem used in the Low Coupling pattern and analyze it for High Cohesion. Assume we have a need to create a cash Payment instance and associate it with the Sale. What class should be responsible for this? Since Register records a Payment in the real - world domain, the Creator pattern suggests Register as a candidate for creating the Payment.
The Register instance could then send an addPaymentmessage to the Sale, passing along the new Payment as a parameter, as shown in Figure Register creates Payment This assignment of responsibilities places the responsibility for making a payment in the Register. The Register is taking on part of the responsibility for fulfilling the makePaymentsystem operation. In this isolated example, this is acceptable; but if we continue to make the Register class responsible for doing some or most of the work related to more and more system operations, it will become increasingly burdened with tasks and become incohesive.
Imagine fifty system operations, all received by Register. If Register did the work related to each, it would become a "bloated" incohesive object.
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The point is not that this single Payment creation task in itself makes the Register incohesive, but as part of a larger picture of overall responsibility assignment, it may suggest a trend toward low cohesion. And most important in terms of developing skills as object designers, regardless of the final design choice, is the valuable achievement that at least we know to consider the impact on cohesion. Since the second design supports both high cohesion and low coupling, it is desirable.
Sale creates Payment Discussion Like Low Coupling, High Cohesion is a principle to keep in mind during all design decisions; it is an underlying goal to continually consider. It is an evaluative principle that a designer applies while evaluating all design decisions.
Grady Booch describes high functional cohesion as existing when the elements of a component such as a class "all work together to provide some well - bounded behavior" [Booch94].
Here are some scenarios that illustrate varying degrees of functional cohesion: Very low cohesion : - A class is solely responsible for many things in very different functional areas. Assume the existence of a class called RDB - RPC' - Interface which is completely responsible for interacting with relational databases and for handling remote procedure calls. These are two vastly different functional areas, and each requires lots of supporting code.
The responsibilities should be split into a family of classes related to KDB access and a family related to RPC support. Low cohesion : - A class has sole responsibility for a complex task in one functional area. Assume the existence of a class called RDBInterfacewhich is completely responsible for interacting with relational databases.
The methods of the class are all related, but there are lots of them, and a tremendous amount of supporting code; there may be hundreds or thousands of methods. The class should split into a family of lightweight classes sharing the work to provide RDB access.
High cohesion : - A class has moderate responsibilities in one functional area and collaborates with other classes to fulfill tasks. Assume the existence of a class called RDBInterfacethat is only partially responsible for interacting with relational databases. It interacts with a dozen other classes related to RDB access in order to retrieve and save objects.
Moderate cohesion : - A class has lightweight and sole responsibilities in a few different areas that are logically related to the class concept but not to each other.
Assume the existence of a class called Company that is completely responsible for knowing its employees and knowing its financial information. These two areas are not strongly related to each other, although both are logically related to the concept of a company. In addition, the total number of public methods is small.
As a rule of thumb, a class with high cohesion has a relatively small number of methods, with highly related functionality, and does not do too much work. It collaborates with other objects to share the effort if the task is large.
A class with high cohesion is advantageous because it is relatively easy to maintain, understand, and reuse. The next section will present the full details of the language. Invariants Integrity constraints in OCL are represented as invariants defined in the context of a specific type, named the context type of the constraint.
Its body, the boolean condition to be checked, must be satisfied by all instances of the context type. OCL derivation rules follow the same structure as init expressions see above although their interpretation is different.
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Note that in this example, the input collection self. Before explaining the type system in a systematic way, let us discuss OCL example types which are already known or which can be deduced from the class diagram of our running example in Fig. The type Set Car is a flat, concrete collection type. Set Car is a reification of the parametrized collection type Set T where T denotes an arbitrary type parameter which can be stubstituted.
Conceptual model of UML can be mastered by learning the following three major elements: Rules to connect the building blocks Common mechanisms of UML Object oriented concepts: UML can be described as the successor of object oriented analysis and design.
An object contains both data and methods that control the data. The data represents the state of the object.
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A class describes an object and they also form hierarchy to model real world system. The hierarchy is represented as inheritance and the classes can also be associated in different manners as per the requirement.
The objects are the real world entities that exist around us and the basic concepts like abstraction, encapsulation, inheritance, polymorphism all can be represented using UML. So UML is powerful enough to represent all the concepts exists in object oriented analysis and design. UML diagrams are representation of object oriented concepts only.
Following are some fundamental concepts of object oriented world: Objects: Objects represent an entity and the basic building block.
Class: Class is the blue print of an object. Abstraction: Abstraction represents the behavior of an real world entity. Encapsulation: Encapsulation is the mechanism of binding the data together and hiding them from outside world.
Inheritance: Inheritance is the mechanism of making new classes from existing one.To capture dynamic behaviour of a system. UML deployment diagram is used to support this perspective. The following diagram is an instance of the system at a particular time of purchase. Sequence diagram is a time dependent view of the interaction between objects to accomplish a behavioral goal of the system. We promote a modular design by creating methods and classes with high cohesion.
Boundary objects are abstractions of the interfaces, entity objects are the application - independent and typically persistent domain software objects, and control objects are use case handlers as described in this Controller pattern. Now the usage of component diagrams can be described as: Another case for components with lower cohesion is with distributed server objects. A class with low cohesion does many unrelated things or does too much work.