APIs
Following is a very incomplete list, as the number of APIs available for the Java platform is overwhelming.
- Rich client platforms
- Office_compliant libraries
- Compression
- JSON
- Game engines
- Real-time libraries
Real time Java is a catch-all term for a combination of technologies that allows programmers to write programs that meet the demands of real-time systems in the Java programming language.
Java's sophisticated memory management, native support for threading and concurrency, type safety, and relative simplicity have created a demand for its use in many domains. Its capabilities have been enhanced to support real time computational needs:
- Java supports a strict priority based threading model.
- Because Java threads support priorities, Java locking mechanisms support priority inversion avoidance techniques, such as priority inheritance or the priority ceiling protocol.
To overcome typical real time difficulties, the Java Community introduced a specification for real-time Java, JSR001. A number of implementations of the resulting Real-Time Specification for Java (RTSJ) have emerged, including a reference implementation from Timesys, IBM's WebSphere Real Time, Sun Microsystems's Java SE Real-Time Systems,[1] Aonix PERC or JamaicaVM from aicas.
The RTSJ addressed the critical issues by mandating a minimum (only two) specification for the threading model (and allowing other models to be plugged into the VM) and by providing for areas of memory that are not subject to garbage collection, along with threads that are not preempt able by the garbage collector. These areas are instead managed using region-based memory management.
Real-Time Specification for Java
The Real-Time Specification for Java (RTSJ) is a set of interfaces and behavioral refinements that enable real-time computer programming in the Java programming language. RTSJ 1.0 was developed as JSR 1 under the Java Community Process, which approved the new standard in November, 2001. RTSJ 2.0 is being developed under JSR 282. A draft version is available at JSR 282 JCP Page. More information can be found at RTSJ 2.0
- Windowing libraries
The windowing library is a set of classes available in the Streams Processing Language (SPL) Runtime C++ API and the SPL Java™ Operator API. The library is used to implement primitive operators that need windows following the SPL window semantics. Using the windowing library provides a consistent window policy semantic across operators, and simplifies the operator implementation.
SPL offers both tumbling and sliding windows. Both types of windows keep all the incoming data in memory until its tuple eviction policy triggers. Use the SPL support for windows when the functionality required by the primitive operator can be built using the semantics provided by SPL window constructs.
One example operator from the SPL Standard Toolkit that uses the windowing library and syntax is the Aggregate operator. An example operator that buffers recently received tuples but that does not use the windowing library and syntax is the DeDuplicate operator. This action occurs because this operator has different eviction and trigger semantics than the ones provided by SPL. This operator needs to maintain only unique tuples and discards all repeated tuples that are received within a time window.
With the windowing library, developers can specify different eviction and trigger policies but can implement the event handling actions independently of the window policy details. There are a few differences when implementing primitive operators in C++ and Java that take advantage of the SPL window clause.
In the C++ implementation, developers have no obligation to use the window library (the preferred practice is to use library). They are free to use the SPL Operator Code Generation API just to get the specified window policy for a given operator instance. Then, they can generate code using other containers. In addition, developers can check for valid window configurations during code generation time.
In the Java implementation, developers must use the window library. This action can be achieved by registering a class that implements com.ibm.streams.operator.window.StreamWindowListener<T> that handles events generated by a window (com.ibm.streams.operator.window.StreamWindow<T>). This use is required because Java operators are not based on code generation. As a result, windows are automatically managed by the runtime to guarantee SPL window semantics. Developers can check for valid window configurations during runtime by checking the window policy associated to a given input port.
- Physics libraries
Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers write once, run anywhere (WORA), meaning that compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax of Java is similar to C and C++, but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities that are typically not available in traditional compiled languages.
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes what is required in a JVM implementation. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform.
Jakarta Enterprise Beans is one of several Java APIs for modular construction of enterprise software. EJB is a server-side software component that encapsulates business logic of an application. An EJB web container provides a runtime environment for web related software components, including computer security, Java servlet lifecycle management, transaction processing, and other web services. The EJB specification is a subset of the Java EE specification.
Java Platform, Micro Edition or Java ME is a computing platform for development and deployment of portable code for embedded and mobile devices. Java ME was formerly known as Java 2 Platform, Micro Edition or J2ME. As of December 22, 2006, the Java ME source code is licensed under the GNU General Public License, and is released under the project name phoneME.
Java Platform, Standard Edition is a computing platform for development and deployment of portable code for desktop and server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE).
Java and C++ are two prominent object-oriented programming languages. By many language popularity metrics, the two languages have dominated object-oriented and high-performance software development for much of the 21st century, and are often directly compared and contrasted. Java's syntax was based on C/C++.
The Connected Limited Device Configuration (CLDC) is a specification of a framework for Java ME applications describing the basic set of libraries and virtual-machine features that must be present in an implementation. The CLDC is combined with one or more profiles to give developers a platform for building applications on embedded devices with very limited resources such as pagers and mobile phones. The CLDC was developed under the Java Community Process as JSR 30 and JSR 139.
This article compares two programming languages: C# with Java. While the focus of this article is mainly the languages and their features, such a comparison will necessarily also consider some features of platforms and libraries. For a more detailed comparison of the platforms, see Comparison of the Java and .NET platforms.
Jakarta Connectors are a set of Java programming language tools designed for connecting application servers and enterprise information systems (EIS) as part of enterprise application integration (EAI). While JDBC is specifically used to establish connections between Java applications and databases, JCA provides a more versatile architecture for connecting to legacy systems. JCA was developed through the Java Community Process, with versions including JSR 16, JSR 112, and JSR 322.
BeanShell is a small, free, embeddable Java source interpreter with object scripting language features, written in Java. It runs in the Java Runtime Environment (JRE), dynamically executes standard Java syntax and extends it with common scripting conveniences such as loose types, commands, and method closures, like those in Perl and JavaScript.
C# is a general-purpose high-level programming language supporting multiple paradigms. C# encompasses static typing, strong typing, lexically scoped, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines.
Real time Java is a catch-all term for a combination of technologies that enables programmers to write programs that meet the demands of real-time systems in the Java programming language.
In the Java computer programming language, an annotation is a form of syntactic metadata that can be added to Java source code. Classes, methods, variables, parameters and Java packages may be annotated. Like Javadoc tags, Java annotations can be read from source files. Unlike Javadoc tags, Java annotations can also be embedded in and read from Java class files generated by the Java compiler. This allows annotations to be retained by the Java virtual machine at run-time and read via reflection. It is possible to create meta-annotations out of the existing ones in Java.
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.
The Java memory model describes how threads in the Java programming language interact through memory. Together with the description of single-threaded execution of code, the memory model provides the semantics of the Java programming language.
The Java language has undergone several changes since JDK 1.0 as well as numerous additions of classes and packages to the standard library. Since J2SE 1.4, the evolution of the Java language has been governed by the Java Community Process (JCP), which uses Java Specification Requests (JSRs) to propose and specify additions and changes to the Java platform. The language is specified by the Java Language Specification (JLS); changes to the JLS are managed under JSR 901. In September 2017, Mark Reinhold, chief Architect of the Java Platform, proposed to change the release train to "one feature release every six months" rather than the then-current two-year schedule. This proposal took effect for all following versions, and is still the current release schedule.
Component Object Model (COM) is a binary-interface standard for software components introduced by Microsoft in 1993. It is used to enable inter-process communication object creation in a large range of programming languages. COM is the basis for several other Microsoft technologies and frameworks, including OLE, OLE Automation, Browser Helper Object, ActiveX, COM+, DCOM, the Windows shell, DirectX, UMDF and Windows Runtime. The essence of COM is a language-neutral way of implementing objects that can be used in environments different from the one in which they were created, even across machine boundaries. For well-authored components, COM allows reuse of objects with no knowledge of their internal implementation, as it forces component implementers to provide well-defined interfaces that are separated from the implementation. The different allocation semantics of languages are accommodated by making objects responsible for their own creation and destruction through reference-counting. Type conversion casting between different interfaces of an object is achieved through the QueryInterface method. The preferred method of "inheritance" within COM is the creation of sub-objects to which method "calls" are delegated.
The Java Development Kit (JDK) is a distribution of Java Technology by Oracle Corporation. It implements the Java Language Specification (JLS) and the Java Virtual Machine Specification (JVMS) and provides the Standard Edition (SE) of the Java Application Programming Interface (API). It is derivative of the community driven OpenJDK which Oracle stewards. It provides software for working with Java applications. Examples of included software are the virtual machine, a compiler, performance monitoring tools, a debugger, and other utilities that Oracle considers useful for a Java programmer.
Windows Runtime (WinRT) is a platform-agnostic component and application architecture first introduced in Windows 8 and Windows Server 2012 in 2012. It is implemented in C++ and officially supports development in C++, Rust/WinRT, Python/WinRT, JavaScript-TypeScript, and the managed code languages C# and Visual Basic .NET (VB.NET).
