Application components of Java 2 Platform, Enterprise Edition support
The Java™ 2 Platform, Enterprise Edition (J2EE) provides the runtime environment for hosting J2EE applications.
The runtime environment defines four application component types
that a J2EE product must support:
- Application clients are Java programming language programs that are typically GUI programs that execute on a desktop computer. Application clients have access to all of the facilities of the J2EE 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.
- Servlets, JavaServer Pages (JSPs), filters, and web event listeners typically execute in a web server and might respond to HTTP requests from web clients. Servlets, JSPs, and filters can be used to generate HTML pages that are an application's user interface. They can also be used to generate XML or other format data that is consumed by other application components. Servlets, pages created with the JSP technology, web filters, and web event listeners are referred to collectively in this specification as web components. Web applications are composed of web components and other data such as HTML pages.
- Enterprise JavaBeans (EJB) components execute in a managed environment that supports transactions. Enterprise beans typically contain the business logic for a J2EE application.
The application components listed above can divided into three
categories, based on how they can be deployed and managed:
- Components that are deployed, managed, and executed on a J2EE server.
- Components that are deployed, managed on a J2EE server, but are loaded to and executed on a client machine.
- Components whose deployment and management are not completely defined by this specification. Application clients can be under this category.
The runtime support for these components is provided by containers.