J2EE

J2EE 1.4 and Web Services

By Sharmishtha Gupta

The J2EE platform is designed to provide server-side and client-side support for developing Web services and distributed, multi-tier enterprise applications. Web Services can provide unlimited functionalities by connecting with an existing service API or creating your own.

If you can efficiently develop and deploy distributed applications and Web services for use on both corporate intranets and over the Internet, you will gain competitive advantage.

J2EE

The J2EE platform is architected to facilitate the deployment of multi-tier distributed applications and Web services. The platform defines different tiers, including a client tier, one or more middle tiers, and a back-end tier. The J2EE platform supports component-based development of applications and services. The portions of application logic that reside on separate tiers can make use of the different components provided by the platform for each tier. To ensure that the components interact in a standard way, the platform introduces the concept of container-based component management. Components run within containers, which are standardized runtime environments that provide specific services to components and thus ensure application portability across platform implementations.

I assume that you already have J2EE platform on your servers, if not you can access it on with downloadable link and installation guide http://www.oracle.com/technetwork/java/javaee/download-141771.html

Web Services

As Web services can be used with any application or technology, the services should be written in such a way that it can communicate with any software, application and technology. The four basic standards required in web services are:

  • Who make services available, and service requestors, who use services, must be able to write Web services using Extensible Markup Language (XML).
  • Simple Object Access Protocol (SOAP) provides a common message format for Web services.
  • All service providers need to have a common format to specify service details, such as the service type, how to access the service, and so forth, which is written in Web Services Description Language (WSDL).
  • Service requestors must have a common way to look up and obtain details of a service. This is accomplished by having common, well-known locations where providers can register their service specifications and where requestors know to go to find services. Universal Description, Discovery, and Integration (UDDI) specification defines a common means for looking up Web services.

Communication between Java Client and Java Web Services on J2EE Platform

In a Web service scenario, a client makes a request to a particular Web service, such as asking for the weather at a certain location, and the service, after processing the request, sends a response to the client to fulfill the request. When both the client and the Web service are implemented in a Java environment, the client makes the call to the service by invoking a Java method, along with setting up and passing the required parameters, and receives as the response the result of the method invocation.

Once the client knows how to access the service, the client makes a request to the service by invoking a Java method, which is passed with its parameters to the client-side JAX-RPC runtime. With the method call, the client is actually invoking an operation on the service. These operations represent the different services of interest to clients. The JAX-RPC runtime maps the Java types to standard XML types and forms a SOAP message that encapsulates the method call and parameters. The runtime then passes the SOAP message through the SOAP handlers, if there are any, and then to the server-side service port.

Java API

Java API for XML-based RPC (JAX-RPC) supports XML-based RPC for Java and J2EE platforms. It enables a traditional client-server remote procedure call (RPC) mechanism using an XML-based protocol. JAX-RPC enables Java technology developers to develop SOAP-based interoperable and portable Web services. Developers use the JAX-RPC programming model to develop SOAP-based Web service endpoints, along with their corresponding WSDL descriptions, and clients. A JAX-RPC-based Web service implementation can interact with clients that are not based on Java. Similarly, a JAX-RPC-based client can interact with a non-Java-based Web service implementation.

Implementation of JAX-RPC Service Endpoint Interface for the weather service interface using a Web component will be like:

public interface WeatherService extends Remote {
	public String getWeather(String city) throws RemoteException;
}

JAX-RPC Service Implementation will be like:

					WeatherService, ServiceLifecycle {

	public void init(Object context) throws JAXRPCException {}

	public String getWeather(String city) {
		return ("Early morning fog clearing midday; " +
				 "over all great day expected in " + city);
	}

	public void destroy() {}
}

A Java/J2EE Client Accessing the Weather Service will be:

Context ic = new InitialContext();
Service svc = (Service)
		ic.lookup("java:comp/env/service/WeatherService");
WeatherSvcIntf port = (WeatherSvcIntf)
		svc.getPort(WeatherSvcIntf.class);
String info = port.getWeather("San Francisco");

This way you need to code very less and yet you can use lot of functionalities in your applications. The equivalent EJB service endpoint implementation for the same weather service.

public class HelloService implements SessionBean {
	private SessionContext sc;

	public WeatherService(){}
	public void ejbCreate() {}
	public String getWeather(String city) {
		return ("Early morning fog clearing midday; " +
				 "over all great day expected in " + city);
	}
	public void setSessionContext(SessionContext sc) {
		this.sc = sc;
	}
	public void ejbRemove() {}
	public void ejbActivate() {}
	public void ejbPassivate() {}
}

A Web service on the J2EE 1.4 platform may be implemented as follows:

  • Using a JAX-RPC service endpoint–The service implementation is a Java class in the Web container. The service adheres to the Web container’s servlet lifecycle and concurrency requirements.
  • Using an EJB service endpoint–The service implementation is a stateless session bean in an EJB container. The service adheres to the EJB container’s lifecycle and concurrency requirements.

There are other ways to write the services code as we will so start from the simple one and then explore more.

By Sharmishtha Gupta
Sharmishtha Gupta is recently graduated with distinction in MBA program at Hult International Business School. She did her under graduation in Electronics & Communications Engineering. She has work experience as PHP Developer for 2 years at 4th largest software company in India. She received highest rating for her performance in building technology systems for social networking websites and designing structure of Apple Inc’s internal software. She also has 2 year of freelance Web Development experience with well established organizations. Currently, she is working with a Horse Racing international company. More articles by Sharmishtha Gupta
Web Development

Why building a gift card option is essential for ecommerce

By Natalie Pavlovskaya
Gift cards possess huge potential for merchants who want to increase revenue, acquire new customers and get their brand noticed. It’s generally believed that a gift card program is a marketing tool perfect only for the biggest holiday season or that it can be applied merely by big brands. However, gift cards can be a great tool to drive customers and increase sales, regardless of the season or the brand size. According to the National Retail Federation 2014 survey, 60% (or 6 in 10) of shoppers say...
C#

A basic database SCRUD class using abstract and generic modifiers

By DeveloperDrive Staff
Introduction ... SCRUD is short for Select, Create, Read, Update and Delete. These are the general actions that any program will perform when working with databases. Yes, there are plenty of ORM applications ( http://en.wikipedia.org/wiki/Object-relational_mapping ) out there that can replace this, but as a general introduction to abstract or generic classes and general development I still think this is worth a read. I should also explain why I have used an abstract class instead of an interface....
DesignBombs

How to Create a Landing Page with Bootstrap 4

By DeveloperDrive Staff
Bootstrap 4 is currently the most popular front-end framework in the world. You can use it to build any kind of user interfaces, from admin templates to full-featured websites. In this step-by-step tutorial, we will have a look at how to build a responsive landing page with Bootstrap 4. You can even use it as a homepage or connect it to a specific marketing campaign. The landing page we will build will have five sections: a fixed navigation bar, a hero section, a three-column "Services" section, a full-width...
WordPress

How to build an auto-ranking Twitter list with WordPress

By James Montgomery
My team and I recently built an awesome list template on WordPress that ranks a set of Twitter users based on follower count. It allows a content writer to easily add a list of Twitter handles, and generate a well designed post. The first piece of content we created with it generated a 1,212% increase in traffic to our site. Check out the tutorial below if you're interested in building it as well. Requirements ... Input Twitter Handle (required) Name (optional) Tagline (optional) Image (optional) Bio...
DesignBombs

How to build your own theme for Grav CMS

By Angie Vella
Grav is an open source flat-file CMS platform, built by the RocketTheme Team. While there are plenty of great CMS platforms available, they are all mostly database-driven, which can be overkill for smaller websites. Instead of a database, Grav uses folders and a basic file structure, it is focused on speed, simplicity, and flexibility. After reading all of the documentation and spending some time trying Grav out, I’m definitely sold and will be using the platform. I hope you will too. What We’ll...
JavaScript

Developing With The HTML5 Element

By Scott Stanton
Videos have been a great way to attract viewers to a website long before YouTube launched back in 2005.  But it wasn’t until the release of HTML5 that web developers have had a lightweight solution to playing the video.  In the past, displaying a video on your site meant your viewer was required to have a Flash or Java-based player installed on their system in order to watch the video.  This was one more thing that would weigh down your site, causing pages to load slower, and be one more thing you’d...
CSS

HTML5 and CSS3 Form Validation

By DeveloperDrive Staff
In HTML5 forms got a major upgrade with the addition of some simple, yet flexible validation attributes. To support these added attributes CSS3 also added several new pseudo selectors styling controls based on their validation state. Adding validation ... To illustrate the new attributes and some of the new input types, we'll be building up a simple sign up form. Every sign up form is essentially the same, you fill in your details and click submit. How many times has the form been reset on you after you've...
HTML

OAuth2 and the LinkedIn API – A WordPress CV/Résumé plugin

By DeveloperDrive Staff
Continuing on from last weeks introduction to OAuth 2.0 using the Twitter API, this week we're going to focus on an alternate implementation of OAuth 2.0 used in the LinkedIn API. This implementation requires that you manually authorize the application before you can get a token. This implementation is a more complex as it requires you to be re-directed to the authentication server, which then re-directs you back to your own site with the approved token. This allows LinkedIn to add additional permissions...
Home CSS Deals DesignBombs HTML HTML5 JavaScript jQuery Miscellaneous Mobile MySQL News PHP Resources Security Snippet Tools Tutorial Web Development Web Services WordPress