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Java Class Loader
The Java class loader, part of the Java Runtime Environment, dynamically loads Java classes into the Java Virtual Machine. Usually classes are only loaded on demand. The virtual machine will only load the class files required for executing the program. The Java run time system does not need to know about files and file systems as this is delegated to the class loader. A software library is a collection of related object code. In the Java language, libraries are typically packaged in JAR files. Libraries can contain objects of different types. The most important type of object contained in a Jar file is a Java class. A class can be thought of as a named unit of code. The class loader is responsible for locating libraries, reading their contents, and loading the classes contained within the libraries. This loading is typically done "on demand", in that it does not occur until the class is called by the program. A class with a given name can only be loaded once by a given class load ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Runtime Environment
Java is a set of computer software and specifications that provides a software platform for developing application software and deploying it in a cross-platform computing environment. Java is used in a wide variety of computing platforms from embedded devices and mobile phones to enterprise servers and supercomputers. Java applets, which are less common than standalone Java applications, were commonly run in secure, sandboxed environments to provide many features of native applications through being embedded in HTML pages. Writing in the Java programming language is the primary way to produce code that will be deployed as byte code in a Java virtual machine (JVM); byte code compilers are also available for other languages, including Ada, JavaScript, Kotlin (Google's preferred Android language), Python, and Ruby. In addition, several languages have been designed to run natively on the JVM, including Clojure, Groovy, and Scala. Java syntax borrows heavily from C and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extensibility
Extensibility is a software engineering and systems design principle that provides for future growth. Extensibility is a measure of the ability to extend a system and the level of effort required to implement the extension. Extensions can be through the addition of new functionality or through modification of existing functionality. The principle provides for enhancements without impairing existing system functions. An extensible system is one whose internal structure and dataflow are minimally or not affected by new or modified functionality, for example recompiling or changing the original source code might be unnecessary when changing a system’s behavior, either by the creator or other programmers. Because software systems are long lived and will be modified for new features and added functionalities demanded by users, extensibility enables developers to expand or add to the software’s capabilities and facilitates systematic reuse. Some of its approaches include facilit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OSGi
OSGi is an open specification and open source project under the Eclipse Foundation. It is a continuation of the work done by the OSGi Alliance (formerly known as the Open Services Gateway initiative), which was an open standards organization for software founded in March 1999. The foundation originally specified and maintained the OSGi standard. The alliance transferred its work to the Eclipse Foundation at the end of 2020. The OSGi specification describes a modular system and a service platform for the Java programming language that implements a complete and dynamic component model, something that does not exist in standalone Java or VM environments. It has a service-oriented architecture based on micro services each implemented as an extended Java class file archive ( JAR (file format)). Description OSGi is built around a service-oriented architecture. Applications or components, come in the form of bundles for deployment, can be remotely installed, started, stopped ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Servlet Container
A web container (also known as a servlet container; and compare "webcontainer" ) is the component of a web server that interacts with Jakarta Servlets. A web container is responsible for managing the lifecycle of servlets, mapping a URL to a particular servlet and ensuring that the URL requester has the correct access-rights. A web container handles requests to servlets, Jakarta Server Pages (JSP) files, and other types of files that include server-side code. The Web container creates servlet instances, loads and unloads servlets, creates and manages request and response objects, and performs other servlet-management tasks. A web container implements the web component contract of the Jakarta EE architecture. This architecture specifies a runtime environment for additional web components, including security, concurrency, lifecycle management, transaction, deployment, and other services. List of Servlet containers The following is a list of notable applications which impleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EAR (file Format)
EAR (''Enterprise'' ''Archive'') is a file format used by Jakarta EE for packaging one or more modules into a single archive so that the deployment of the various modules onto an application server happens simultaneously and coherently. It also contains XML files called deployment descriptors which describe how to deploy the modules. Ant, Maven, or Gradle can be used to build EAR files. File structure An EAR file is a standard JAR file (and therefore a Zip file) with an .ear extension, with one or more entries representing the modules of the application, and a metadata directory called META-INF which contains one or more deployment descriptors. * META-INF/ ** application.xml: This is the main deployment descriptor for the EAR. It lists all the modules included in the EAR and specifies configuration settings. ** MANIFEST.MF: The manifest file that provides metadata about the archive. * JAR Files: ** These files contain Enterprise JavaBeans (EJB) modules or utility classes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WAR (file Format)
In software engineering, a WAR file (Web Application Resource or Web application ARchive) is a file used to distribute a collection of JAR (file format), JAR-files, Jakarta Server Pages, Jakarta Servlets, Java (programming language), Java class (file format), classes, XML files, tag libraries, static web pages (HTML and related files) and other resources that together constitute a web application. Content and structure A WAR file may be digital signature, digitally signed in the same way as a JAR (file format), JAR file in order to allow others to determine where the source code came from. There are special files and directories within a WAR file: * The /WEB-INF directory in the WAR file contains a file named web.xml which defines the structure of the web application. If the web application is only serving JSP files, the web.xml file is not strictly necessary. If the web application uses servlets, then the servlet container uses web.xml to ascertain to which Jakarta Servlet, serv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jakarta EE
Jakarta EE, formerly Java Platform, Enterprise Edition (Java EE) and Java 2 Platform, Enterprise Edition (J2EE), is a set of specifications, extending Java SE with specifications for enterprise features such as distributed computing and web services. Jakarta EE applications are run on reference runtimes, which can be microservices or application servers, which handle transactions, security, scalability, concurrency and management of the components they are deploying. Jakarta EE is defined by its specification. The specification defines APIs (application programming interface) and their interactions. As with other Java Community Process specifications, providers must meet certain conformance requirements in order to declare their products as ''Jakarta EE compliant''. Examples of contexts in which Jakarta EE referencing runtimes are used are: e-commerce, accounting, banking information systems. History The platform created by Sun Microsystems was known as ''Java 2 Platform, E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspect-oriented Programming
In computing, aspect-oriented programming (AOP) is a programming paradigm that aims to increase modularity by allowing the separation of cross-cutting concerns. It does so by adding behavior to existing code (an advice) ''without'' modifying the code, instead separately specifying which code is modified via a " pointcut" specification, such as "log all function calls when the function's name begins with 'set. This allows behaviors that are not central to the business logic (such as logging) to be added to a program without cluttering the code of core functions. AOP includes programming methods and tools that support the modularization of concerns at the level of the source code, while aspect-oriented software development refers to a whole engineering discipline. Aspect-oriented programming entails breaking down program logic into cohesive areas of functionality (so-called ''concerns''). Nearly all programming paradigms support some level of grouping and encapsulation of conce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspect Weaver
An aspect weaver is a metaprogramming utility for aspect-oriented languages designed to take instructions specified by aspects (isolated representations of significant concepts in a program) and generate the final implementation code. The weaver integrates aspects into the locations specified by the software as a pre- compilation step. By merging aspects and classes (representations of the structure of entities in the program), the weaver generates a woven class. Aspect weavers take instructions known as '' advice'' specified through the use of pointcuts and join points, special segments of code that indicate what methods should be handled by aspect code. The implementation of the aspect then specifies whether the related code should be added before, after, or throughout the related methods. By doing this, aspect weavers improve modularity, keeping code in one place that would otherwise have been interspersed throughout various, unrelated classes. Motivation Many programmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encryption
In Cryptography law, cryptography, encryption (more specifically, Code, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Despite its goal, encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor. For technical reasons, an encryption scheme usually uses a pseudo-random encryption Key (cryptography), key generated by an algorithm. It is possible to decrypt the message without possessing the key but, for a well-designed encryption scheme, considerable computational resources and skills are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users. Historically, various forms of encryption have been used to aid in cryptography. Early encryption ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Bytecode
Java bytecode is the instruction set of the Java virtual machine (JVM), the language to which Java and other JVM-compatible source code is compiled. Each instruction is represented by a single byte, hence the name bytecode, making it a compact form of data. Due to the nature of bytecode, a Java bytecode program is runnable on any machine with a compatible JVM, without the lengthy process of compiling from source code. Java bytecode is used at runtime either interpreted by a JVM or compiled to machine code via just-in-time (JIT) compilation and run as a native application. As Java bytecode is designed for a cross-platform compatibility and security, a Java bytecode application tends to run consistently across various hardware and software configurations. Relation to Java In general, a Java programmer does not need to understand Java bytecode or even be aware of it. However, as suggested in the IBM developerWorks journal, "Understanding bytecode and what bytecode is li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
