Welcome
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Do and Learn
Create a hello world service with EGL
In this tutorial, you will learn how to build a simple web service with EGL. Then, you will create a client that uses this service.
Introduction
In this tutorial, you will learn how to build a simple web service with EGL. Then, you will create a client that uses this service.

Overview
Getting started
- Tutorials
- Do and Learn
  - Introducing EGL
    In this tutorial, you will learn how to build a simple dynamic web site using EGL. This site has two pages: one to display a list of records in a database and another to allow users to change the data from one of those records.
  - Create a hello world program with EGL
    In this tutorial, you will learn how to write and run your first EGL program. Although the program you create will not be powerful or complex, it will demonstrate how an EGL program works.
  - Create a hello world service with EGL
    In this tutorial, you will learn how to build a simple web service with EGL. Then, you will create a client that uses this service.
    - Introduction
      In this tutorial, you will learn how to build a simple web service with EGL. Then, you will create a client that uses this service.
    - Lesson 1: Create an EGL web project for the service
      EGL projects can act as services, as clients, or as both simultaneously. For this tutorial, you will create two projects: one to act as the service and one to act as the client. While you could put all the code into a single EGL project, using two projects demonstrates how EGL can call services in another application.
    - Lesson 2: Set up the service
      Now that you have written the code for this service, you can make it available to other applications as a web service. Making the service available in this way involves creating service binding information, which tells other applications where to find the service and what functions are available in the service. The service publishes this information as a Web Services Description Language (WSDL) file.
    - Lesson 3: Create an EGL service client
      The next step is to create a client project to use the service. While the client you create in this tutorial is in the same workspace, you can imagine that it is in a completely separate location or on a different platform. Since services and clients do not need to be written in the same code language, you can also imagine that this client application is written in a different language or is created with an entirely different set of tools.
    - Lesson 4: Set up the project as a client
      Just like the service project, the client project uses an EGL deployment descriptor file. However, in the client project, the EGL deployment descriptor will hold information about where to find services. You will import the WSDL file you created from the service and EGL will add appropriate binding information to the EGL deployment descriptor so the client can find the service.
    - Summary
      This is the end of the tutorial Create a hello world service with EGL.
  - Create a mortgage application with EGL Rich UI
    Create a Rich UI application so that the user can do the following tasks: calculate monthly mortgage payments, given a loan amount and interest rate; display a pie chart that tells the interest and principal for the life of the mortgage; retrieve any of the payment calculations that were provided earlier to the same user; and display a map of the mortgage lenders who have offices in one or another U.S. zip code.
  - Access a database with EGL Rich UI
    In this tutorial, you create a Rich UI application so that the user can access rows in an SQL database.
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Introduction

In this tutorial, you will learn how to build a simple web service with EGL. Then, you will create a client that uses this service.

This tutorial might require some optionally installable components. To ensure that you installed the appropriate optional components, see the System requirements list.

Service-oriented architecture is a method of organizing applications in modular pieces called services and clients. The services provide logic to the clients in the form of functions, in much the same way that EGL libraries make functions available to programs. However, in service-oriented architecture, the services are stateless, meaning that they do not remember interactions with a particular client. In this way, each time the service is called, it is as though that service is being used for the first time. Services are also able to provide their functionality to a wide variety of applications through the WSDL standard, promoting flexibility and code reuse.

Learning objectives

In this tutorial, you learn to do the following tasks:

Create and configure an EGL project
Create a web service with EGL
Configure an EGL project to act as a service or as a client at run time
Create a web page controlled by EGL
Test an application on a web application server

Time required

To complete this tutorial, you will need approximately 90 minutes. If you decide to explore other facets of EGL or web services while working on the tutorial, it could take longer to finish.

Skill level

Intermediate

System requirements

Enterprise Generation Language
WebSphere® Application Server

Prerequisites

There are no prerequisites for this tutorial.

Tutorial application

In this tutorial, you will create a simple web service in EGL. This service accepts a person's name and the name of a city and returns a string combining the two, such as "Bill, welcome to New York!" You will use the service-oriented architecture tools included in Rational® Business Developer Extension to expose this service as a web service and publish the information about the service in a WSDL file.

The EGL service code

You will then create a project to act as a client for this service. This project includes a simple web page that retrieves the two input parameters, passes them to the service, and displays the output from the service on the page:

The finished client page