Misplaced Pages

#687312

23-399: From version 1.1 on, JAX-RS is an official part of Java EE 6. A notable feature of being an official part of Java EE is that no configuration is necessary to start using JAX-RS. For non-Java EE 6 environments a small entry in the web.xml deployment descriptor is required. JAX-RS provides some annotations to aid in mapping a resource class (a POJO ) as a web resource. The annotations use

46-563: A "Backing Bean". The example below uses Contexts and Dependency Injection (CDI) and Jakarta Enterprise Beans ( EJB ). To implement business logic, Jakarta Enterprise Beans ( EJB ) is the dedicated technology in Jakarta EE. For the actual persistence, JDBC or Jakarta Persistence (JPA) can be used. The example below uses EJB and JPA. Not explicitly shown is that JTA is used under the covers by EJB to control transactional behavior. For defining entity/model classes Jakarta EE provides

69-623: A common client API and support for Hypermedia following the HATEOAS -principle of REST . In May 2013, it reached the Final Release stage. On 2017-08-22 JAX-RS 2.1 specification final release was published. Main new supported features include server-sent events , reactive clients, and JSON-B. Implementations of JAX-RS include: Java Platform, Enterprise Edition Jakarta EE , formerly Java Platform, Enterprise Edition ( Java EE ) and Java 2 Platform, Enterprise Edition ( J2EE ),

92-399: A database in a transactional way, managing distributed queues. The Jakarta EE APIs include several technologies that extend the functionality of the base Java SE APIs , such as Jakarta Enterprise Beans , connectors , servlets , Jakarta Server Pages and several web service technologies. In an attempt to limit the footprint of web containers, both in physical and in conceptual terms,

115-598: A product until December 1996 when Sun shipped JWS. This was before what is now the Jakarta EE was made into a specification. The Servlet1 specification was created by Pavni Diwanji while she worked at Sun Microsystems , with version 1.0 finalized in June 1997. Starting with version 2.2, the specification was developed under the Java Community Process . Three methods are central to the life cycle of

138-593: A server-side servlet web API . Such web servlets are the Java counterpart to other dynamic web content technologies such as PHP and ASP.NET . A Jakarta Servlet is a Java class in Jakarta EE that conforms to the Jakarta Servlet API, a standard for implementing Java classes that respond to requests. Servlets could in principle communicate over any client–server protocol, but they are most often used with HTTP . In principle, any servlets can extend

161-407: A servlet and using URL mapping with a servlet. Before servlet 3.0 specification (Tomcat 7.0), configuring the web.xml to map a servlet to a URL was the only option. For applications using the servlet 3.0 specification or later, the @WebServlet annotation can be used to map any servlet to one or more URL patterns. Servlets may be packaged in a WAR file as a web application . A web container

184-545: A servlet. These are init() , service() , and destroy() . They are implemented by every servlet and are invoked at specific times by the server. The following is a typical user scenario of these methods. The following example servlet prints how many times its service() method was called. Note that HttpServlet is a subclass of GenericServlet , an implementation of the Servlet interface. The service() method of HttpServlet class dispatches requests to

207-487: A web form for editing a user. In Jakarta EE a (web) UI can be built using Jakarta Servlet , Jakarta Server Pages ( JSP ), or Jakarta Faces ( JSF ) with Facelets . The example below uses Faces and Facelets . Not explicitly shown is that the input components use the Jakarta EE Bean Validation API under the covers to validate constraints. To assist the view, Jakarta EE uses a concept called

230-839: 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 . The platform

253-399: Is an object that receives a request and generates a response based on that request. The basic Servlet package defines Java objects to represent servlet requests and responses, as well as objects to reflect the servlet's configuration parameters and execution environment. The Servlet API , contained in the Java package hierarchy javax.servlet , defines the expected interactions of

SECTION 10

#1732783813688

276-508: Is only responsible for processing, and the JSP is only responsible for presenting the HTML, allowing for a clear separation of concerns and conformance to the single-responsibility principle . While the direct usage of servlets to generate HTML (as shown in the example below) has become rare, the higher level MVC web framework in Jakarta EE ( Faces ) still explicitly uses the servlet technology for

299-486: Is required for deploying and running a servlet. A web container (also known as a servlet container) is essentially the component of a web server that interacts with the servlets. The 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. Servlets can be generated automatically from Jakarta Server Pages (JSP) by

322-631: The GenericServlet class; however, realistically speaking, all servlets extend the HttpServlet class. Thus "servlet" is often used as shorthand for "HTTP servlet". Thus, a servlet can be used to add dynamic content to a web server using the Java platform . The generated content is commonly HTML , but may be other data such as XML and more commonly, JSON . The Jakarta Servlet API has, to some extent, been superseded by two standard Java technologies for web services: A Servlet

345-522: The Jakarta Server Pages compiler . The difference between servlets and JSP is that servlets typically embed HTML inside Java code, while JSPs embed Java code in HTML. In general, when using JSPs, embedding Java code in JSP is considered bad practice. Instead, a better approach would be to move the back-end logic from the JSP to the Java code in the Servlet . This ensures that the Servlet

368-542: The Java package jakarta.ws.rs (previously was javax.ws.rs but was renamed on May 19, 2019). They include: In addition, it provides further annotations to method parameters to pull information out of the request. All the @*Param annotations take a key of some form which is used to look up the value required. In January 2011 the JCP formed the JSR 339 expert group to work on JAX-RS 2.0. The main targets are (among others)

391-629: The Jakarta Persistence ( JPA ), and for expressing constraints on those entities it provides the Bean Validation API. The example below uses both these technologies. Jakarta Servlet A Jakarta Servlet , formerly Java Servlet is a Java software component that extends the capabilities of a server . Although servlets can respond to many types of requests, they most commonly implement web containers for hosting web applications on web servers and thus qualify as

414-523: The low level request/response handling via the FacesServlet . A somewhat older usage is to use servlets in conjunction with JSPs in a pattern called " Model 2 ", which is a flavor of the model–view–controller . The Java Servlet API was first publicly announced at the inaugural JavaOne conference in May 1996. About two months after the announcements at the conference, the first public implementation

437-620: The use of javax and Java trademarks. Oracle owns the trademark for the name "Java" and the platform was renamed from Java EE to Jakarta EE. The name refers to the largest city on the island of Java and also the capital of Indonesia, Jakarta . The name should not be confused with the former Jakarta Project which fostered a number of current and former Java projects at the Apache Software Foundation . Jakarta EE includes several specifications that serve different purposes, like generating web pages, reading and writing from

460-490: The web container and a servlet. The package javax.servlet.http defines HTTP -specific subclasses of the GenericServlet . This package includes session management objects that track multiple requests and responses between the web server and a client. Servlets can maintain state in session variables across many server transactions by using HTTP cookies , or URL mapping . There are several ways of creating

483-649: The web profile was created, a subset of the Jakarta EE specifications. The Jakarta EE web profile comprises the following: Although by definition all Jakarta EE implementations provide the same base level of technologies (namely, the Jakarta 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. The code sample shown below demonstrates how various technologies in Java EE 7 are used together to build

SECTION 20

#1732783813688

506-565: Was known as Java 2 Platform, Enterprise Edition or J2EE from version 1.2, until the name was changed to Java Platform, Enterprise Edition or Java EE in version 1.5. Java EE was maintained by Oracle under the Java Community Process . On September 12, 2017, Oracle Corporation announced that it would submit Java EE to the Eclipse Foundation . The Eclipse top-level project has been named Eclipse Enterprise for Java (EE4J). The Eclipse Foundation could not agree with Oracle over

529-542: Was made available on the JavaSoft website. This was the first alpha of the Java Web Server (JWS; then known by its codename Jeeves ) which would eventually be shipped as a product on June 5, 1997. In his blog on java.net , Sun veteran and GlassFish lead Jim Driscoll details the history of servlet technology. James Gosling first thought of servlets in the early days of Java , but the concept did not become

#687312