JavaEE6 MyWayJava, Java, Tomcat, Eclipse EE

PART 1/2- WebComponents

4 dec 2013

Requirements

Soft requirements, go and seeTomEE Appunti Devoxx2012

JavaEE WebApp Components

JavaEE WebApp Files

JavaEE WebApp ReleaseThe process for creating, deploying, and executing a web application can be summarized as follows:1. Develop the web component code.2. Develop the web application deployment descriptor, if necessary.3. Compile the web application components and helper classes referenced by

the components.4. Optionally, package the application into a deployable unit.5. Deploy the application into a web container.6. Access a URL that references the web application.

TomEE - WebProfileTomEEThe Web Profile version of TomEE containsWEB COMPONENT

● JSF - Apache MyFaces● JSP - Apache Tomcat● JSTL - Apache Tomcat● Servlet - Apache Tomcat

JAVABEANS COMPONENT● CDI - Apache OpenWebBeans● EJB - Apache OpenEJB● JPA - Apache OpenJPA● JTA - Apache Geronimo Transaction● Javamail - Apache Geronimo JavaMail● Bean Validation - Apache BVal

TomEE+TomEE+The TomEE Plus distribution adds the following:

WEB COMPONENTS● JAX-RS - Apache CXF ● JAX-WS - Apache CXF

JAVABEANS COMPONENTS● JMS - Apache ActiveMQ● Connector - Apache Geronimo Connector

WebClientBrowser but not only...

WebComponents

WebComponentsJava EE web components are either servlets or pages created using JSP technology (JSP pages) and/or JavaServer Faces technology.

No JSF pleasehttp://davidwburns.wordpress.com/2012/04/23/why-i-dont-use-java-server-faces-jsf/

One: JSF isn’t easier than standard web programming

Two: At the mercy of the implementation

Three: You’re cut off from the rest of the web community

Four: The web is meant to be stateless

Five: Be honest. Are you just using JSF as a crutch?

Don’t use JSF to avoid learning the web.

HTML5 for the clientPure HTML5 clients are all we need.

ServletStill core and getting better… more efficient technologies are in JavaEE7 Servlet3.1.

Asynchronous Servlets

/** approccio sincrono (classico) **/var dato = ottieniDatoDaRemoto(url);alert(dato);

/** approccio ad eventi (asincrono) **/ottieniDatoDaRemoto(url, function(dato) { alert(dato);}); //la funzione ritorna subito

JavaEE6 Servlet 3.0Servlet 3.0 allowed asynchronous request processing but only traditional I/O was permitted. This can restrict scalability of your applications. In a typical application, ServletInputStream is read in a while loop.

public class TestServlet extends HttpServlet {

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws IOException, ServletException {

ServletInputStream input = request.getInputStream();

byte[] b = new byte[1024];

int len = -1;

while ((len = input.read(b)) != -1) {

. . .

}

}

}

JavaEE7 Servlet 3.1If the incoming data is blocking or streamed slower than the server can read then the server thread is waiting for that data. The same can happen if the data is written to ServletOutputStream.

This is resolved in Servet 3.1 (JSR 340, released as part Java EE 7) by adding event listeners - ReadListener and WriteListener interfaces. These are then registered using ServletInputStream.setReadListener and ServletOutputStream.setWriteListener. The listeners have callback methods that are invoked when the content is available to be read or can be written without blocking.

Java WebServices● JAX-WS: addresses advanced QoS requirements commonly occurring in enterprise

computing. When compared to JAX-RS, JAX-WS makes it easier to support the WS-* set of protocols, which provide standards for security and reliability, among other things, and interoperate with other WS-* conforming clients and servers.

● JAX-RS: makes it easier to write web applications that apply some or all of the constraints of the REST style to induce desirable properties in the application, such as loose coupling (evolving the server is easier without breaking existing clients), scalability (start small and grow), and architectural simplicity (use off-the-shelf components, such as proxies or HTTP routers). You would choose to use JAX-RS for your web application because it is easier for many types of clients to consume RESTful web services while enabling the server side to evolve and scale. Clients can choose to consume some or all aspects of the service and mash it up with other web-based services.

JAX-WS

http://tomee.apache.org/examples-trunk/simple-webservice/README.html

In our testcase we see how to create a client for our Calculator service via the javax.xml.ws.Service class and leveraging our CalculatorWs endpoint interface.

JAX-WS stepsOfficial JEE6 tutorial

The basic steps for creating a web service and client are as follows:1. Code the implementation class.2. Compile the implementation class.3. Package the files into a WAR file.4. Deploy the WAR file. The web service artifacts, which are used to communicate with

clients, are generated by the GlassFish Server during deployment.5. Code the client class.6. Use a wsimport Ant task to generate and compile the web service artifacts needed to

connect to the service.7. Compile the client class.8. Run the client.

JAX-WS notesTomEE container is configured and packaged with Apache CXF .

TomEE leave the use od wsimport optional.

Whether or not you use annotations it's important to understand the performance impact they can have on a server at startup. In order for the server to discover annotations on classes, it must load the classes, which means that at startup, a server will look through all the classes in WEB-INF/classes and WEB-INF/lib, looking for annotations. (Per the specification, servers don't have to look outside these two places.) You can avoid this search when you know you don't have any annotations by specifying a metadata-complete attribute on the <web-app> root like this:

<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="3.0" metadata-complete="true"></web-app>

Run a TomEE example* Create a Dynamic Web Project* Add web.xml, beans.xml, index.html* Add Unit4 library* Add your package* Create example sources

SOAP WS Manual Testing

RESTFull WebServicesResource identification through URI: A RESTful web service exposes a set of resources that identify the targets of the interaction with its clients. Resources are identified by URIs, which provide a global addressing space for resource and service discovery.

Uniform interface: Resources are manipulated using a fixed set of four create, read, update, delete operations: PUT, GET, POST, and DELETE. PUT creates a new resource, which can be then deleted by using DELETE. GET retrieves the current state of a resource in some representation. POST transfers a new state onto a resource.

Self-descriptive messages: Resources are decoupled from their representation so that their content can be accessed in a variety of formats, such as HTML, XML, plain text, PDF, JPEG, JSON, and others. Metadata about the resource is available and used, for example, to control caching, detect transmission errors, negotiate the appropriate representation format, and perform authentication or access control.

Stateful interactions through hyperlinks: Every interaction with a resource is stateless; that is, request messages are self-contained. Stateful interactions are based on the concept of explicit state transfer. Several techniques exist to exchange state, such as URI rewriting, cookies, and hidden form fields. State can be embedded in response messages to point to valid future states of the interaction.

JAX-RS Code@Path("/greeting")

public class SimpleRest {

@GET

public String message() {

return "Hi get REST!";

}

@POST

public String lowerCase(final String message) {

return "Hi post REST!".toLowerCase();

}

}

REST WS Manual Testing

JavaBeans Components

JavaBeansComponentsWeb components are supported by the services of a runtime platform called a web container. A web container provides such services as request dispatching, security, concurrency, and lifecycle management. A web container also gives web components access to such APIs as naming, transactions, and email.

Enterprise JavaBeansEnterprise beans are Java EE components that implement Enterprise JavaBeans (EJB) technology. Enterprise beans run in the EJB container. The EJB container provides system-level services, such as transactions and security, to its enterprise beans.

To be continued...Thank you!

Riferimentihttp://docs.oracle.com/javaee/6/tutorial/doc/index.html

http://davidwburns.wordpress.com/2012/04/23/why-i-dont-use-java-server-faces-jsf/

http://www.html.it/pag/32814/introduzione-a-nodejs/

https://blogs.oracle.com/arungupta/entry/non_blocking_i_o_using

http://blog.sortedset.com/step-by-step-web-services-with-tomcat-tomee-apache-cxf-eclipse/

http://www.javacodegeeks.com/2013/08/async-servlet-feature-of-servlet-3.html