User:M3tainfo/Java Platform, Enterprise Edition

Java Platform, Enterprise Edition or Java EE is Oracle's enterprise Java computing platform. The platform provides an API and runtime environment for developing and running enterprise software, including network and web services, and other large-scale, multi-tiered, scalable, reliable, and secure network applications. Java EE extends the Java Platform, Standard Edition (Java SE), providing an API for object-relational mapping, distributed and multi-tier architectures, and web services. The platform incorporates a design based largely on modular components running on an application server. Software for Java EE is primarily developed in the Java programming language. The platform emphasizes Convention over configuration and annotations for configuration. Optionally XML can be used to override annotations or to deviate from the platform defaults.

History
The platform was known as Java 2 Platform, Enterprise Edition or J2EE until the name was changed to ''Java Platform, Enterprise Edition or Java EE'' in version 5. The current version is called Java EE 7.


 * J2EE 1.2 (December 12, 1999)
 * J2EE 1.3 (September 24, 2001)
 * J2EE 1.4 (November 11, 2003)
 * Java EE 5 (May 11, 2006)
 * Java EE 6 (Dec 10, 2009)
 * Java EE 7 (May 28, 2013, but April 5, 2013 according to spec document. June 12, 2013 was the planned kickoff date )

The Java EE 7 platform incorporates a number of improvements and enhancements over previous versions, including support for the latest web standards such as HTML 5, Web Sockets and JSON as well as modern HTTP and REST web services using JAX-RS. Dependency injection using CDI is now supported more broadly across the platform by APIs such as JMS and includes a new interceptor mechanism.

Although Java EE 7 does not require any new JDK features, upcoming APIs and standards are expected to be designed with Java SE 8 language changes in mind. It is also expected that a future Java EE 8 release will include support for cloud environments and platforms.

The Java EE 7 platform adds first-class support for recent developments in web standards, including Web Sockets and JSON, which provide the underpinnings for HTML 5 support in Java EE. Java EE 7 also adds a modern HTTP client API as defined by JAX-RS 2.0.

Also new in the Java EE 7 platform is the Batch API, which provides a programming model for batch applications and a runtime for scheduling and executing jobs, and the Concurrency Utilities API, which provides asynchronous capabilities by means of managed executor service, managed scheduled executor service, managed thread factory, and context service.

The CDI dependency injection facility introduced in Java EE 6 is enhanced as well as more broadly utilized by the Java EE 7 platform technologies, and the managed bean model is further aligned to remove inconsistencies among Java EE component classes in aspects of CDI injection and interceptor support. The declarative transaction functionality introduced by EJB is been made available in a more general way through CDI interceptors, so that it may be leveraged by other managed beans. The Bean Validation facility is extended to the automatic validation of method invocations and likewise made available via CDI interceptors.

Java EE 7 also continues the "ease of development" focus of Java EE 5 and Java EE 6. Most notably, Java EE 7 includes a revised and greatly simplified JMS 2.0 API. Ease of development encompasses ease of configuration as well. To that end, Java EE 7 broadens the resource definition facilities introduced in Java EE 6 to encompass more of the standard platform resource types, and also provides default database and JMS connection factory resources. It also improves the configuration of application security, including new descriptors for security permissions. Java EE 7 further simplifies the platform by making optional the technologies that were identified as candidates for pruning in Java EE 6, namely: EJB Entity Beans, JAX-RPC 1.1, JAXR 1.0, and JSR-88 1.2.

Finally, Java EE 7 lays groundwork for enhancements to the platform for use in cloud environments in a future release. Such features include resource definition metadata, improved security configuration, and support for database schema generation via the Java Persistence API.

Architecture
The Java EE architecture is based on Containers which are runtime environments that provide services to application components. These include Web, EJB and Application Client containers

Containers
Containers provide the runtime support for Java EE application components. Containers provide a federated view of the underlying Java EE APIs to the application components. Java EE application components never interact directly with other Java EE application components. They use the protocols and methods of the container for interacting with each other and with platform services.

The Containers, denoted by the separate rectangles, are Java EE runtime environments that provide required services to the application components represented in the upper half of the rectangle. The services provided are denoted by the boxes in the lower half of the rectangle. For example, the Application Client Container provides Java Message Service (JMS) APIs to Application Clients, as well as the other services represented. All these services are explained below. See Section EE.2.7, “Java EE Standard Services”.

The arrows represent required access to other parts of the Java EE platform. The Application Client Container provides Application Clients with direct access to the Java EE required Database through the Java API for connectivity with database systems, the JDBCTM API. Similar access to databases is provided to JSP pages, JSF applications, and servlets by the Web Container, and to enterprise beans by the EJB Container.

As indicated, the APIs of the JavaTM Platform, Standard Edition (Java SE), are supported by Java SE runtime environments for each type of application component.

This specification requires that containers provide a Java CompatibleTM runtime environment, as defined by the Java Platform, Standard Edition, v7 specification (Java SE).

Java EE Servers
Underlying a Java EE container is the server of which it is a part. A Java EE Product Provider typically implements the Java EE server-side functionality using an existing transaction processing infrastructure in combination with Java Platform, Standard Edition (Java SE) technology. The Java EE client functionality is typically built on Java SE technology.

Resource Adapters
A resource adapter is a system-level software component that typically implements network connectivity to an external resource manager. A resource adapter can extend the functionality of the Java EE platform either by implementing one of the Java EE standard service APIs (such as a JDBCTM driver), or by defining and implementing a resource adapter for a connector to an external application system.

Database
The Java EE platform requires a database, accessible through the JDBC API, for the storage of business data. The database is accessible from web components, enterprise beans, and application client components.

Profiles
A profile is a configuration of the Java EE platform targeted at a specific class of applications.

Profiles are not a new concept, nor are they unique to the Java EE platform. The Java Community Process Document (version 2.8) gives the following definition of a profile: “A Specification that references one of the Platform Edition Specifications and zero or more other JCP Specifications (that are not already a part of a Platform Edition Specification). APIs from the referenced Platform Edition must be included according to the referencing rules set out in that Platform Edition Specification. Other referenced specifications must be referenced in their entirety.”

All Java EE profiles share a set of common features, such as naming and resource injection, packaging rules, security requirements, etc. This guarantees a degree of uniformity across all products and, indirectly, applications that fall under the “Java EE platform” umbrella. This also ensures that developers who are familiar with a certain profile, or with the full platform, can move easily to other profiles, avoiding excessive compartmentalization of skills and experience.

Beyond the basic functionality outlined above, profiles are free to include any set of technologies that are part of the platform, provided that all rules in the present specification that pertain to the included technologies—either alone or in combination with others—are followed.

Components
The Java EE runtime environment defines four application component types that a Java EE product must support:


 * Application clients are Java programming language programs that are typically GUI programs that execute on a desktop computer. Application clients offer a user experience similar to that of native applications and have access to all of the facilities of the Java EE middle tier.


 * Applets are GUI components that typically execute in a web browser, but can execute in a variety of other applications or devices that support the applet programming model. Applets can be used to provide a powerful user interface for Java EE applications. (Simple HTML pages can also be used to provide a more limited user interface for Java EE applications.)


 * Servlets, JSPpages, JSF applications, filters, and web event listeners typically execute in a web container and may respond to HTTP requests from web cli- ents. Servlets, JSP pages, JSF applications, and filters may be used to generate HTML pages that are an application’s user interface. They may also be used to generate XML or other format data that is consumed by other application components. A special kind of servlet provides support for web services using the SOAP/HTTP protocol. Servlets, pages created with the JavaServer Pages technology or JavaServer Faces technology, web filters, and web event listeners are referred to collectively in this specification as “web com- ponents.” Web applications are composed of web components and other data such as HTML pages. Web components execute in a web container. A web server includes a web container and other protocol support, security support, and so on, as required by Java EE specifications.


 * Enterprise JavaBeans (EJB) components execute in a managed environment that supports transactions. Enterprise beans typically contain the business logic for a Java EE application. Enterprise beans may directly provide web services using the SOAP/HTTP protocol.

Standards and Specifications
Java EE is defined by its specification. As with other Java Community Process specifications, providers must meet certain conformance requirements in order to declare their products as Java EE compliant.

Java EE includes several API specifications, such as JDBC, RMI, e-mail, JMS, web services, XML, etc., and defines how to coordinate them. Java EE also features some specifications unique to Java EE for components. These include Enterprise JavaBeans, Connectors, servlets, JavaServer Pages and several web service technologies. This allows developers to create enterprise applications that are portable and scalable, and that integrate with legacy technologies. A Java EE application server can handle transactions, security, scalability, concurrency and management of the components it is deploying, in order to enable developers to concentrate more on the business logic of the components rather than on infrastructure and integration tasks.

Java EE Specifications

HTTP
The HTTP client-side API is defined by the java.net package. The HTTP server- side API is defined by the servlet, JSP, and JSF interfaces and by the web services support that is a part of the Java EE platform.

HTTPS
Use of the HTTP protocol over the SSL protocol is supported by the same client and server APIs as HTTP.

Java Transaction API (JTA)
An application-level demarcation interface that is used by the container and application components to demarcate transaction boundaries.

RMI-IIOP
The RMI-IIOP subsystem is composed of APIs that allow for the use of RMI-style programming that is independent of the underlying protocol, as well as an implementation of those APIs that supports both the Java SE native RMI protocol (JRMP) and the CORBA IIOP protocol.

Java IDL
Java IDL allows Java EE application components to invoke external CORBA objects using the IIOP protocol.

JDBC API
The JDBC API is the API for connectivity with relational database systems.

Java Persistence API
The Java Persistence API is the standard API for the management of persistence and object/relational mapping.

Java Message Service (JMS)
The Java Message Service is a standard API for messaging that supports reliable point-to-point messaging as well as the publish-subscribe model.

Java Naming and Directory Interface (JNDI)
The JNDI API is the standard API for naming and directory access.

JavaMail
Many Internet applications require the ability to send email notifications, so the Java EE platform includes the JavaMail API along with a JavaMail service provider that allows an application component to send Internet mail.

JavaBeans Activation Framework (JAF)
The JAF API provides a framework for handling data in different MIME types, originating in different formats and locations. The JavaMail API makes use of the JAF API. The JAF API is included in Java SE and so is available to Java EE applications.

XML Processing
The Java API for XML Processing (JAXP) provides support for the industry standard SAX and DOM APIs for parsing XML documents, as well as support for XSLT transform engines.

Java EE Connector Architecture
The Connector architecture is a Java EE SPI that allows resource adapters that support access to Enterprise Information Systems to be plugged in to any Java EE product.

Security Services
The JavaTM Authentication and Authorization Service (JAAS) enables services to authenticate and enforce access controls upon users. It implements a Java technology version of the standard Pluggable Authentication Module (PAM) framework and supports user-based authorization. The JavaTM Authorization Service Provider Contract for Containers (JACC) defines a contract between a Java EE application server and an authorization service provider, allowing custom authorization service providers to be plugged into any Java EE product. The JavaTM Authentication Service Provider Interface for Containers (JASPIC) defines an SPI by which authentication providers implementing message authentication mechanisms may be integrated in client or server message processing containers or runtimes.

Web Services
Java EE provides full support for both clients of web services as well as web service endpoints.

Concurrency Utilities
The Concurrency Utilities for Java EE is a standard API for providing asynchronous capabilities to Java EE application components through the following types of objects: managed executor service, managed scheduled executor service, managed thread factory, and context service.

Batch
The Batch Applications for the Java Platform API (Batch) provides a programming model for batch applications and a runtime for scheduling and executing jobs.

Management
The Java 2 Platform, Enterprise Edition Management Specification defines APIs for managing Java EE servers using a special management enterprise bean.

Deployment
The Java 2 Platform, Enterprise Edition Deployment Specification defines a contract between deployment tools and Java EE products.

Technologies and APIs
The Java EE APIs includes several technologies that extend the functionality of the base Java SE APIs.

Servlets
Servlet 3.1 JSR 340


 * Optimize the PaaS model for Web applications.
 * Multi tenancy for security, session, resources, etc.
 * Asynchronous IO based on NIO2
 * Simplfiied asynchronous Servlets
 * Utilize Java EE concurrency utilities
 * Enable support for WebSockets

The servlet specification defines a set of APIs to service mainly HTTP requests. It includes the JavaServer Pages (JSP) specification.

Enterprise JavaBeans
EJB 3.2 JSR 345


 * Enhancements to the EJB architecture to enable PaaS, such as multi-tenancy
 * Factorization of container-managed transactions to use outside EJB
 * Further use of annotations
 * Alilgnment and integration with other specifications in the platform

The Enterprise JavaBean (EJB) specification defines a set of lightweight APIs that an object container (the EJB container) will support in order to provide transactions (using JTA), remote procedure calls (using RMI or RMI-IIOP), concurrency control, dependency injection and access control for business objects. This package contains the Enterprise JavaBeans classes and interfaces that define the contracts between the enterprise bean and its clients and between the enterprise bean and the ejb container.

Java Persistence API
JPA 2.1 JSR 338


 * Support for multi-tenancy
 * Support for stored procedures and vendor function
 * Update and Delete Critieria queries
 * Support for schema generation
 * Persistence Context synchronisation
 * CDI injection into listeners

This package contains the classes and interfaces that define the contracts between a persistence provider and the managed classes and the clients of the Java Persistence API (JPA).

JAX-RS
JAX-RS 2.0 JSR 339


 * Client API - low level using builder pattern and possibly a higher level on top of that
 * Hypermedia - easily create and process links associated with resources
 * Form or Query parameter validation using Bean Validation
 * Closer integration with @Inject, etc
 * Server-side asynchronous request processing
 * Server-side content negotiation using "qs"

Java Server Faces
JSF 2.2 JSR 344


 * Ease of Development - making configuration options dynamic, make cc:interface in composite components optional, shorthand URLs for Facelet tag libraries, integration with CDI, OSGi support for JSF artifacts
 * Support implementation of Portlet Bridge 2.0 (JSR 329)
 * Support for HTML5 features like HTML5 Forms, Metadata, Heading and Section content model
 * Flow management, Listener for page navigation events, and new components like FileUpload and BackButton

This package defines the root of the JavaServer Faces (JSF) API. JSF is a technology for constructing user interfaces out of components.

This package defines the component part of the JavaServer Faces (JSF) API. Since JSF is primarily component oriented, this is one of the core packages. The package overview contains a UML diagram of the component hierarchy.

Java Message Server
JMS 2.0 JSR 343


 * Ease of development - changes to the JMS programming model to make the application development simpler and easier
 * Remove/Clarify ambiguities in the existing specification
 * Integration with CDI
 * Clarification of the relationship between JMS and other Java EE specs
 * A new mandatory API to allow any JMS provider to be integrated with any Java EE container
 * Multi-tenancy and other cloud-related features from the platform

This package defines the Java Message Service (JMS) API. The JMS API provides a common way for Java programs to create, send, receive and read an enterprise messaging system's messages.

Expression Language
EL 3.0 JSR 341


 * Separate ELContext into parsing and evaluation contexts
 * Customizable EL coercion rules
 * Reference static methods and members directly in EL expressions
 * Adding operators like equality, string concatenation, and sizeof etc.
 * Integration with CDI such as generating events before/during/after the expressions are evaluated

This package defines the classes and interfaces for Java EE's Expression Language. The Expression Language (EL) is a simple language originally designed to satisfy the specific needs of web application developers. It's used specifically in JSF to bind components to (backing) beans and in CDI to name beans, but can be used throughout the entire platform.

JSON Processing
JSR 353


 * Produce and consume JSON text in a streaming fashion, similar to StAX API for XML
 * Build a Java object model for JSON text using API classes, similar to DOM API for XML

Web Socket API


The Java API for WebSocket specification defines a set of APIs to service WebSocket connections.

Concurrency Utilities for Java EE
JSR 236


 * Provides a clean, simple, independent API by building on JSR 166, making it appropriate for use within any Java EE contianer.

This package provides the interfaces for interacting directly with Java EE's platform default managed thread pool. A higher-level executor service working on this same thread pool can be used optionally. The same interfaces can be used for user-defined managed thread pools, but this relies on vendor specific configuration and is not covered by the Java EE specification.

CDI
CDI 1.1 JSR 346


 * Global ordering of interceptors and decorators
 * API for managing built-in contexts
 * Embedded mode to allow startup outside Java EE container
 * Declarative control over which packages/beans are scanned in an archive
 * Injection for static members such as loggers
 * Send Servlet events as CDI event

These packages define the injection annotations for the contexts and Dependency Injection (CDI) APIs.

These packages define the context annotations and interfaces for the Contexts and Dependency Injection (CDI) API.

JCache
JCache JSR 107

API and semantics for temporary, in-memory caching of Java objects, including object creation, shared access, spooling, invalidation, and consistency across JVMs

Bean Validation
Bean Validation 1.1 JSR 349


 * Integration with other Java EE specs
 * JAX-RS: Validate parameters and return values on HTTP calls
 * JAXB: Convert constraints into XML schema descriptor
 * Method level validation
 * Apply constraints on group collection
 * Extend the model to support AND and OR style composition

This package contains the annotations and interfaces for the declarative validation support offered by the Bean Validation API. Bean Validation provides a unified way to provide constraints on beans (e.g. JPA model classes) that can be enforced cross-layer. In Java EE, JPA honors bean validation constraints in the persistence layer, while JSF does so in the view layer.

Batch Application for the Java Platform
Batch JSR 352


 * Programming model for batch applications and a runtime for scheduling and executing jobs
 * Defines Batch Job, Batch Job Step, Batch Application, Batch Executor, and Batch Job Manager for the standard programming model

This package defines the entry AP for Java EE Batch Applications. The Batch Applications API provides the means to run long running background tasks that possibly involve a large volume of data and which may need to be periodically executed.

Java Transaction API
JTA 1.2 JSR 907

This package provides the Java Transaction API (JTA) that contains the interfaces and annotations to interact with the transaction support offered by Java EE. Even though this API abstracts from the really low-level details, the interfaces are also considered somewhat low-level and the average application developer in Java EE is either assumed to be relying on transparent handling of transactions by the higher level EJB abstractions, or using the annotations provided by this API in combination with CDI managed beans.

JASPIC
This package provides the core of the Java Authentication SPI (JASPIC) that contains the interfaces and classes to build authentication modules for secure Java EE applications. Authentication modules are responsible for the interaction dialog with a user (e.g. redirecting to a Form or to an OpenID provider), verifying the user's input (e.g. by doing an LDAP lookup, database query or contacting the OpenID provider with a token) and retrieving a set of groups/roles that the authenticated user is in or has (e.g. by again doing an LDAP lookup or database query).

Java EE Connector Architecture
JCA 1.7 JSR 322

This package defines the Java EE Connector Architecture (JCA) API. Java EE Connector Architecture (JCA) is a Java-based technology solution for connecting application servers and enterprise information systems (EIS) as part of enterprise application integration (EAI) solutions. This is a low-level API aimed at vendors that the average application developer typically does not come in contact with.

JavaServer Pages
JSP 2.3 JSR 245

Standard Tag Library for JavaServer Pages
JSTL 1.2 JSR 52

Dependency Injection for Java
DI 1.0 JSR 330

Common Annotations for the Java Platform
Common Annotations 1.2 JSR 250

JavaMail
JavaMail 1.5 JSR 919

Interceptors
Interceptors 1.2 JSR 318

(Maintenance Release covered under JSR 318)

XML
Implementing Enterprise Web Services 1.3 JSR 109

Java API for XML-Based Web Services (JAX-WS) 2.2 JSR 224

Web Services Metadata for the Java Platform JSR 181

Java API for XML-Based RPC (JAX-RPC) 1.1 (Optional) JSR 101

Java APIs for XML Messaging 1.3 JSR 67

Java API for XML Registries (JAXR) 1.0 JSR 93

Differences between implementations
Although by definition all Java EE implementations provide the same base level of technologies (namely, the Java EE spec and the associated APIs), they can differ considerably with respect to extra features (like connectors, clustering, fault tolerance, high availability, security, etc.), installed size, memory footprint, startup time, etc.