OOPs Technology Definitions

Alphabetically Arranged Glossary of Terms used commonly in Java Application Development.

A

• Architecture : The overall structure of a system. Architecture takes into consideration the the overall working of the system as well as the non-functional requirements( scalability, security, portability) of the system. Software architecture is the high-level structure of a software system.
• Abstraction : The process of picking out (abstracting) common features of objects and procedures. A programmer would use abstraction, for example, to note that two functions perform almost the same task and can be combined into a single function. Abstraction is one of the most important techniques in software engineering and is closely related to two other important techniques -- encapsulation and information hiding. All three techniques are used to reduce complexity.
• Abstract Class : A class that provides common behavior across a set of subclasses but is not itself designed to have instances that work. An abstract class represents a concept; classes derived from it represent implementations of the concept.
• Accessor Methods : Methods that an object provides to define the interface to its instance variables. The accessor method to return the value of an instance variable is called a get method or gettermethod, and the accessor method to assign a value to an instance variable is called a setmethod or settermethod.
• ACID : The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.
• Applet A Java program designed to run within a Web browser. Contrast with application.
• Application In Java programming, a self-contained, stand-alone Java program that includes a main() method. Contrast with applet.
• Application Server : A server program that allows the installation of application specific software components, in a manner so that they can be remotely invoked, usually by some for of remote object method call.
• Attribute : A specification of a property of a bean.
• Algorithms : A formula or set of steps for solving a particular problem. To be an algorithm, a set of rules must be unambiguous and have a clear stopping point. Algorithms can be expressed in any language, from natural languages like English or French to programming languages like FORTRAN.

  B

• Base Class : A class from which other classes or beans are derived. A base class may itself be derived from another base class.
• Bean : A definition or instance of a JavaBeans component.
• Bean-Managed Persistence (BMP) : When an Enterprise JavaBeans performs its own long-term state management.
• Break Point : A point in a computer program where the execution can be halted.
• Blueprint : Something intended as a guide for making something else
• Black Box Testing :Also known as functional testing. Asoftware testing technique whereby the internal workings of the item being tested are not known by the tester. For example, in a black box test on a software design the tester only knows the inputs and what the expected outcomes should be and not how the program arrives at those outputs. The tester does not ever examine the programming code and does not need any further knowledge of the program other than its specifications.

  C

• Class : (1) A class is a collection of data and methods to operate on that data. (2) A Class can also be thought of as a Template to create Objects. (3) An aggregate that defines properties, operations, and behavior for all instances of that aggregate.
• Class Hierarchy : The relationships between classes that share a single inheritance. All Java classes inherit from the Object class.
• Class Library : A collection of classes.
• Classification : The grouping of entities by classes or categories.
• Collection A set of features in which each feature is an object.
• Component : Component can be defined as a unit which provides some agreed upon functionality for which it is designed.
• Commit : The operation that ends a unit of work and updates the database such that other processes can access any changes made.
• Common Object Request Broker Architecture (CORBA) : A middleware specification which defines a software bus—the Object Request Broker (ORB)—that provides the infrastructure.
• Component Model : An architecture and an API that allows developers to define reusable segments of code that can be combined to create a program. Eg (JavaBeans component model)
• Composite Bean : A bean that is composed of a bean and one or more subbeans. A composite bean can contain visual beans, nonvisual beans, or both.
• Concrete Class : A subclass of an abstract class that is a specialization of the abstract class.
• Container-Managed Persistence (CMP) : When an Enterprise JavaBeans server manages a bean’s long-term state.
• Construction From Parts : A software development technology in which applications are assembled from existing and reusable software components, known as parts.
• Constructor : A special class method that has the same name as the class and is used to construct and possibly initialize objects of its class type.
• Container : A component that can hold other components. In Java, examples of containers include applets, frames, and dialogs.
• Cursor : A database control structure used by the Data Access Builder to point to a specific row within some ordered set of rows and to retrieve rows from a set, possibly making updates or deletions.

  D

• Decompose : Separate into constituent elements or parts
• Design Pattern : A The Gang of Four described patterns as "a solution to a problem in a context". These three things -- problem, solution, and context -- are the essence of a pattern."Abstracting solutions to recurring design problems".
• Data Abstraction : A data type with a private representation and a public set of operations. The Java language uses the concept of classes to implement data abstraction.
• Distributed Computing Environment (DCE) :Adopted by the computer industry as a de facto standard for distributed computing. DCE allows computers from a variety of vendors to communicate transparently and share resources such as computing power, files, printers, and other objects in the network.
• Distributed Component ObjectModel (DCOM) : A protocol that enables software components to communicate directly over a network in a reliable, secure, and efficient manner. Previously called "Network OLE," DCOM is designed for use across multiple network transports, including Internet protocols such as HTTP. DCOM is based on the Open Software Foundation's DCE-RPC specification and works with both Java applets and ActiveX components through its use of the Component Object Model (COM).
• DMZ : Demilitarized Zone.
• DTD : Document type definition.
• DLL :dynamic link library. A file containing executable code and data bound to a program at run time rather than at link time. The C++ Access Builder generates beans and C++ wrappers that let your Java programs access C++ DLLs.

  E

• Extreme Programming : A discipline of software development that follows a specific structure that is designed to simplify and expedite the process of developing new software. Kent Beck developed Extreme Programming to be used with small teams of developers who need to develop software quickly in an environment of rapidly-changing requirements. XP teams design software for specific functionalities without adding any functionalities that are not specifically requested that may slow down the process, keeping the development course simple through systematic and regular testing and design improvements.
• Encapsulation :(1) In programming, the process of combining elements to create a new entity. Put in a short or concise form, reduce in volume, Enclose in a capsule or other small container. Object-oriented programming languages rely heavily on encapsulation to create high-level objects. Encapsulation is closely related to abstraction and information hiding. (2) The hiding of a software object’s internal representation. The object provides an interface that queries and manipulates the data without exposing its underlying structure.
• EJB :Enterprise JavaBeans. A server component developed by SUN Microsystems.
• Event : An action by a user program, or a specification of a notification that may trigger specific behavior. In JDK 1.1, events notify the relevant listener classes to take appropriate actions.

  F

• Field : A data object in a class. For example, a customer class could have a name field and an address field. A field can itself be an object with its own behavior and fields. By default, a field, in contrast to a property, does not support event notification.
• Framework : A set of cooperative classes with strong connections that provide a template for development.

  G

• GIGO : Garbage in, Garbage out, often abbreviated as GIGO. This is a famous computer axiom meaning that if invalid data is entered into a system, the resulting output will also be invalid. Although originally applied to computer software, the axiom holds true for all systems, including, for example, decision-making systems.
• Garbage Collection : A Smalltalk process for periodically identifying unreferenced objects and deallocating their memory.
• Gateway : A host computer that connects networks that communicate in different languages. For example, a gateway connects a company’s LAN to the Internet.
• GUI :graphical user interface (GUI). A type of interface that enables users to communicate with a program by manipulating graphical features, rather than by entering commands. Typically, a graphical user interface includes a combination of graphics, pointing devices, menu bars and other menus,overlapping windows, and icons.

  H

• HTTPS : When you need to ensure the integrity and privacy of information that is sent over a network, especially an open one like the Internet, one of the options is to use the HTTPS protocol, rather than standard HTTP. HTTPS is normal HTTP wrapped by a Secure Sockets Layer (SSL). SSL is a communication system that ensures privacy when communicating with other SSL-enabled applications. It's really just a protocol that runs on top of the TCP/IP layer. It encrypts the data through the use of symmetric encryption and digital certificates. An SSL connection can only be established between a client and server when both systems are running in SSL mode and are able to authenticate each other.

  I

• Integrity : An unreduced or unbroken completeness or totality.
• Inheritance :(1) A mechanism by which an object class can use the attributes, relationships, and methods defined in more abstract classes related to it (its base classes). (2) An object-oriented programming technique that allows you to use existing classes as bases for creating other classes.
• Instance : Synonym for object, a particular instantiation of a data type.
• Interface : (1) An interface specifies a collection of abstract methods that must be overridden by classes that implement the interface. (2) A set of methods that can be accessed by any class in the class hierarchy.
• Information Hiding :The process of hiding details of an object or function. Information hiding is a powerful programming technique because it reduces complexity. One of the chief mechanisms for hiding information is encapsulation -- combining elements to create a larger entity. The programmer can then focus on the new object without worrying about the hidden details.

  J

• Java archive (JAR) : A platform-independent file format that groups many files into one. JAR files are used for compression, reduced download time, and security. Because the JAR format is written in Java, JAR files are fully extensible.
• JavaBeans : In JDK 1.1, the specification that defines the platform-neutral component model used to represent parts. Instances of JavaBeans (often called beans) may have methods, properties, and events.
• JNDI : Java Naming and Directory Interace (JNDI). The Java standard API for accessing directory services, such as LDAP, COS Naming, and others.
• JNI :Java Native Interface (JNI). In JDK 1.1, the specification that defines a standard naming and calling convention so that the Java virtual machine can locate and invoke methods written in a language different from Java. See also native method.
• JSP : JavaServer Pages.
• JTA : Java Transaction API.
• JTS : The Java Transaction Service based on the CORBA Transaction Service which provides a way for middleware vendors to build interoperable transactional middleware.

  K

• Keyword : A predefined word, reserved for Java, that cannot be used as an identifier.

  L

• LDAP : Lightweight Directory Access Protocol for accessing X.500 directories.
• Listener : In JDK 1.1, a class that receives and handles events.

  M

• Member : (1) A data object in a structure or a union. (2) In Java, classes and structures can also contain functions and types as members.
• Method : A fragment of Java code within a class that can be invoked and passed a set of parameters to perform a specific task.
• Method call : A communication from one object to another that requests the receiving object to execute a method. A method call consists of a method name that indicates the requested method and the arguments to be used in executing the method. The method call always returns some object to the requesting object as the result of performing the method. Synonym for message.
• Message : A request from one object that the receiving object implement a method. Because data is encapsulated and not directly accessible, a message is the only way to send data from one object to another. Each message specifies the name of the receiving object, the method to be implemented, and any arguments the method needs for implementation. Synonym for method call.
• Model : A nonvisual bean that represents the state and behavior of an object, such as a customer or an account. Contrast with view.
• MVC : Model-View-Controller.
• Native method : Method written in a language other than Java that can be called by a Java object through the JNI specification.

  N

• Named package : A package that has been explicitly named and created.
• Nonvisual bean : In the Visual Composition Editor, a bean that has no visual representation at run time. A nonvisual bean typically represents some real-world object that exists in the business environment. Compare with model. Contrast with viewand visual bean.
• Notification framework : In JDK 1.1, a set of classes that implement the notifier/listener protocol. The notification framework is the base of the construction from beans technology (Visual Composition Editor).

  O

• Object :(1) A computer representation of something that a user can work with to perform a task. An object can appear as text or an icon. (2) A collection of data and methods that operate on that data, which together represent a logical entity in thesystem. In object-oriented programming, objects are grouped into classes that share common data definitions and methods. Each object in the class is said to be an instance of the class. (3) An instance of an object class consisting of attributes, a data structure, and operationalmethods. It can representon, place, thing, event, or concept. Each instance has the same properties, attributes, and methods as other instances of the object class, although it has unique values assigned to its attributes.
• Object class : A template for defining the attributes and methods of an object. An object class can contain other object classes. An individual representation of an object class is called an object.
• Object factory : A nonvisual bean capable of dynamically creating new instances of a specified bean. For example, during the execution of an application, an object factory can create instances of a new class to collect the data being generated.
• Object Request Broker (ORB) : A CORBA term designating the means by which objects transparently make requests and receive responses from objects, whether they are local or remote.
• Open Database Connectivity (ODBC) A Microsoft developed C database API that allows access to database management systems calling callable SQL, which does not require the use of an SQL preprocessor. In addition, ODBC provides an architecture that allows users to add modules (database drivers) that link the application to their choice of database management systems at run time. Applications no longer need to be directly linked to the modules of all the database management systems that are supported.
• Operation : A method or service that can be requested of an object.
• OSE : Open servlet engine.
• Overloading : An object-oriented programming technique that allows redefinition of methods when the methods are used with class types.

  P

• Package : A program element that contains related classes and interfaces.
• Parameter connection : A connection that satisfies a parameter of an action or method by supplying either a property’s value or the return value of an action, method, or script. The parameter is always the source of the connection. See also connection.
• Primitive bean : A basic building block of other beans. A primitive bean can be relatively complex in terms of the function it provides.
• Property : An initial setting or characteristic of a bean; for example, a name, font, text, or positional characteristic.
• Property-to-method connection : A connection that calls a method whenever a property’s value changes. It is similar to an event-to-method connection because the property’s event ID is used to notify the method when the value of the property changes. See also connection.
• Property-to-property connection : A connection from a property of one bean to a property of another bean. When one property is updated, the other property is updated automatically. See also connection.
• Prototype : A method declaration or definition that includes both the return type of the method and the types of its arguments.
• Proxy bean : A group of client-side and server-side objects that represent a remote server bean. The top-level class that implements the proxy bean is the client-side server proxy. See also client-side server proxy and server-side server proxy.

  R

• RMI : Remote Method Invocation (RMI). In JDK 1.1, the API that enables you to write distributed Java programs, allowing methods of remote Java objects to be accessed from other Java virtual machines. remote object instance manager. Creates and manages instances of RMI server beans through their associated server-side server proxies.
• Resource file : A noncode file that can be referred to from your Java program in VisualAge for Java. Examples include graphics and audio files.
• RMI compiler : The compiler that generates stub and skeleton files that facilitate RMI communication. This compiler can be automatically invoked by the RMI Access Builder or from the Tools menu item.
• RMI registry : A server program that allows remote clients to get a reference to a server bean.
• Roll back : The process of restoring data changed by SQL statements to the state at its last commit point.

  S

• Schema : In the Data Access Builder, the representation of the database that will be mapped.
• Schema mapping : In the Data Access Builder, a set of definitions for all attributes matching all columns for your database table, view, or SQL statement. The mapping contains the information required by the Data Access Builder to generate Java classes.
• Server bean : The bean that is distributed using RMI services and deployed on a server.
• Server-side server proxy : Generated by the RMI Access Builder, a companion class to the client-side server proxy, facilitating client-side server proxy communication over RMI.
• Service : A specific behavior that an object is responsible for exhibiting.
• SQL predicate : The conditional part of an SQL statement.
• Stored procedure : A procedure that is part of a relational database. The Data Access Builder can generate Java code that accesses stored procedures.
• Slipstream :To add enhancements to or fix bugs in software without creating a new version number to identify the changes.
• Software Entropy :The tendency for software, over time, to become difficult and costly to maintain. A software system that undergoes continuous change, such as having new functionality added to its original design, will eventually become more complex and can become disorganized as it grows, losing its original design structure. In theory, it may be better to redesign the software in order to support the changes rather than building on the existing program, but redesigning the software is more work because redesigning the existing software will introduce new bugs and problems.

  T

• Tear-off property : A property that a developer has exposed to work with as though it were a stand-alone bean.
• Thread : A unit of execution within a process.
• Transaction : In a CICS program, an event that queries or modifies a database that resides on a CICS server.
• Type : A generic term for a class or interface.

  U

• UIML :Short for User Interface Markup Language, a markup language extension of XML that promotes the creation of Web pages that can be viewed on any kind of interface device, from PC monitors to smart phones to PDAs. Using UIML style sheets, Web content can be created once without knowing specifically which devices it will be viewed on.

  V

• Versioning : The act of making an open edition a versioned edition; that is, making the edition read-only.
• View : (1) A visual bean, such as a window, push button, or entry field. (2) A visual representation that can display and change the underlying model objects of an application. Views are both the end result of developing an application and the basic unit of composition of user interfaces. Compare with visual bean. Contrast with model.

  W

• White Box Testing :Also known as glass box, structural, clear box and open box testing. A software testing technique whereby explicit knowledge of the internal workings of the item being tested are used to select the test data. Unlike black box testing, white box testing uses specific knowledge of programming code to examine outputs. The test is accurate only if the tester knows what the program is supposed to do. He or she can then see if the program diverges from its intended goal. White box testing does not account for errors caused by omission, and all visible code must also be readable.
• Widget :Pronounced wih-jit. (1) A generic term for the part of a GUI that allows the user to interface with the application and operating system. Widgets display information and invite the user to act in a number of ways. Typical widgets include buttons, dialog boxes, pop-up windows, pull-down menus, icons, scroll bars, etc.

Status Code Categories
Numeric Value	Meaning
100-199		Informational - Request has been received, continuing to process it.
200-299		Success - The action was successfully received, understood, and accepted.
300-399		Redirection - Further action must be taken in order to complete the request.
400-499		Client Error - The request contains bad syntax or cannot be fulfilled.
500-599		Server Error - The server failed to fulfill an apparently valid request.

Common HTTP Response Status Codes
Code		Meaning
200		OK - The request has succeeded.
302		Moved Temporarily - The request resides temporarily under a different URI. 
		If the new URI is a location, the location header field in the response will
		give the new URL. This is typically used when the client is being redirected.
400		Bad Request - The server couldn't understand the request due to malformed syntax.
401		Unauthorized - The request requires authentication and/or authorization.
403		Forbidden - The server understood the request, but for some reason is refusing
		to fulfill it. The server may or may not reveal why it has refused the request.
404		Not Found - The server has not found anything matching the request URI.
500		Internal Server Error - The server encountered an unexpected condition 
		which prevented it from fulfilling the request.