It performs well in situation where systems are undergoing continuous design, adaption, and maintenance. It identifies the objects in problem domain, classifying them in terms of data and behavior. All tangible entities student, patient and some intangible entities bank account are modeled as object.
A Reflective Object-Oriented Architecture for Developing Fault-Tolerant Software
It defines the operation performed on objects. Objects with similar meaning and purpose grouped together as class. They are nothing more than an action that an object can perform. They are information sent to objects to trigger methods. Essentially, a message is a function or procedure call from one object to another. Encapsulation is a process of information hiding. It is simply the combination of process and data into a single entity. Data of an object is hidden from the rest of the system and available only through the services of the class.
It allows improvement or modification of methods used by objects without affecting other parts of a system. It is a process of taking or selecting necessary method and attributes to specify the object.
Object Oriented Approach
It focuses on essential characteristics of an object relative to perspective of user. All the classes in the system are related with each other. The objects do not exist in isolation, they exist in relationship with other objects. It indicates that two classes are similar but have some differences. Polymorphism is the ability to take on many different forms. It applies to both objects and operations.
A polymorphic object is one who true type hides within a super or parent class.
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During the past year, OODT achieved two major accomplishments: we matured our software framework into a production-like technology; and we transferred that technology outside of JPL. The service is extensible and can be customized for specific needs, such as returning profiles for sets of documentation in a knowledgebase, or profiles for transient software objects.
In addition, we have created a root profile server whose job is to describe other profile servers.
hyecotemterabo.tk By starting a query at this root level, any described resource can be discovered. A scientist may request an radar image from Alpha Regio on Venus in JPEG format, even though the image may be stored in a mission-specific bitmap format. Different product servers offer different facilities for accessing and converting products. We've had successes with technology transfer as well. OODT served as the middleware for their engineering lifecycle support system, brokering information from simulations and models between a commercially-maintained simulation environment and Methedit analysis tools developed by JPL.
Finally, and most importantly, the success of this technology towards bridging separate scientific disciplines has caught the attention of the National Institutes of Health NIH. We are in the process of transferring our query, product and archive service technologies to the EDRN, while at the same time parterning with EDRN researchers to bring them into the workflowfurther broadening our requirements analysis and resulting feature support.
It uses four hierarchically arranged levels M0 to M3. The meta-meta level M3 specifies the metadata of the modeling language and its relationships using the metaobject facility MOF. It defines the meta-model, and also enables metadata transfer. The XMI format defined by the object management group members is a practical tool for sharing object-oriented data at the meta-meta level between development tools.
The image shows that the metamodeling of UML 2.
Table of Contents
It represents concrete, real objects and individual data records - e. Level M1 comprises all models that describe and structure the data of level M0.
These are UML diagrams such as the activity diagram or the package diagram explained below. To define the structure of these models, M2 meta-models define the specifications and semantics of the model elements. The highest level, M3, is a meta-model of the meta-model.
The mentioned meta-object facility works on an abstract level that defines meta-models. This level defines itself, since otherwise further, superordinate meta-levels would arise. UML layer M2 defines the rules for its own semantics. The language units are terms defined in UML 2. This means a formal representation that everyone involved can understand is possible. Language units abstract similarly structured and similarly functioning objects and processes, and give them a visually representable form.
Depending on the hierarchy level within the model, elements take on more specialized tasks or define other elements more closely. Class: As a language unit, classes are a core aspect of UML. You define what a class is and how classes interact with each other. This language unit has four levels, ranging from simple elements to more complex relationships:. Components: Components are software modules that separate their contents from the external system.
There is only a connection to the outside through interfaces or port. A composition connector establishes a connection to another component via the interface. The delegation connector links internal elements with an interface at the external border. Components are modular and interchangeable. Composite structure: The composite structure of language units describes elements that are shielded inwards and outwards like components.
Only ports connect the content to the external system. The so-called encapsulated classifiers are composed of elements called parts. Parts communicate via connectors.
Profile: A profile configures UML 2. Abstract terms such as activity or object must be specified for some projects to increase understanding. You can use a profile to adjust semantics and notations that are loosely set. Model: The model includes all elements necessary to represent a specific view of the structure or behavior of a system. This also includes external influences such as actors.
Action: When it comes to depicting behavior, actions are central. They represent a single step within an activity — an activity, in turn, is a behavior which is made up of a collection of actions. Here are some examples of actions:. It contains three specifications:. Distribution: A network consists of objects that are connected to each other in meshes. A special case of application exists if these elements represent executable software or artifacts.
These artifacts run on execution environments or devices that UML 2.
Related Distrib. Obj.-Oriented Data-Systs. Design
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