17_Developing the Business Tier Web Services

8/14/2019 17_Developing the Business Tier Web Services

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17Copyright 2007, Oracle. All rights reserved.

Developing the Business Tier with

Web Services


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17-2 Copyright 2007, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to do

the following:

Define Service-Oriented Architecture (SOA)

Describe the benefits of Web services Identify Web services components

Create a Web service

Utilize a Web service from a client


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What Is Service-Oriented

Architecture (SOA)?

SOA is a software design pattern that implements a set

of reusable services by using standard elements:

Service

description

Communication protocol

Service

registry


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SOA: Development Life Cycle

Orchestrate

Change

Integrate

Manage

Secure

Monitor

Develop


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What Is a Web Service?

A Web service is:

A software component whose technology is based

on a set of standards for building interoperable

distributed applications A set of self-describing business functions

Service oriented

Component based


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7/4217-7 Copyright 2007, Oracle. All rights reserved.

Benefits of Web Services

Distributed component model with interoperability

XML format for representing data. The request andresponse messages are in the XML format.

Programming language independent Easily accessible with standard protocols such as

HTTP, HTTPS, SMTP, and FTP

Communication through firewalls

Existing components can be exposed as

Web Services to save development time Different communication styles:

RPC style (synchronous)

Message style (asynchronous)



Web Services and SOA

Web services are a technology that can be used in

SOA:

Service

description(WSDL)

Communication protocol (SOAP)

Service

registry

(UDDI)



Web Services Model

Web Servicesdirectory

(UDDI)

XML interface (WSDL)

Web service

Find

Invoke Publish

1

2

3

XML interface (WSDL)

Client application

SOAP



Anatomy of a Service

Service consumer

Interface Proxy

Service

interface

Service

implementation

New service

Wrapped

legacy

Composite

service



Defining Web Services

A Web service is:

A self-describing business function

A small application sending data to a Web browser

using Web services

Web services:

Refer to a standard set of platform independentmessaging protocols (SOAP, HTTP, JMS)

Enable connections between services from any

Web-connected device

Exchange data and functionality in XML format

Web ServiceWeb browser

Request

Response



WSDL

Web Service(J2EE, PL/SQL,

.NET,C/C++,

Legacy )

Web Serviceclient

(J2EE, .NET,

PL/SQL )

Points to

description

Describes and

Points to

Web Service

Finds

service

Invokes with

XML messages

Basic Web Services

SOAP

UDDI

registry



Two Development Use Cases

Service

implementation

Example: EJB/Java

class to WSDL

Example: WSDL contract as the

interface and message description

Bottom-Up Top-Down/Contract Driven

WSDL WSDL

Service

implementation



JAX-RPC

Core Web services standard for Java:

Enables portability across containers

Standard class and interface structure for client and

server

Various hook points for custom serializers, custom

handlers, attachments

Tools must provide abstractions to handle service

as a set of classes.

Navigator structure for quick location Wizard support for declarative definition



Simple Object Access Protocol (SOAP)

Supports RPC or message-oriented information

exchange

Features:

Protocol independence Language independence

Platform independence

Attachments (MIME)

Message consists of envelope

containing header (optional)

and body

SOAP header

SOAP body



Web Services Definition

Language (WSDL)

Is a definition language to define Web service

interfaces and how to invoke them

Is an XML Schema for defining Web services: Service interface definition: Describes what

message must be sent and what message isreturned

Service implementation definition: Describes towhich address the message must be sent

Allows both the messages and the operations on

the messages to be defined abstractly in XML Answers three key questions about a Web service:

What does a service do?

How is a service accessed?

Where is a service located?



Web Services Definition

Language (WSDL)

... ... ....

.. ..



Anatomy of a WSDL Document

A

has a number of

with input

and output.

A

composed of

describes the structure

of an .

A

describes

style of an

.

A

describes describesthe and

for a

specific .



Other Web Service Features

Run and test

Deploy

Use Http Analyzer

Test for WS-Icompliance

WSDL

Running service

Quality of Service Reliability, security

Auditing, logging



Using Http Analyzer

Sets dummy proxy

Intercepts messages

Configurable

Headers

Next/Previous Resend



Why Web Services and Applications?

UIGeneration

Binding

abstraction

DatabaseApplication server(s)Client

Business

Service

Facade

Rules

EngineBPEL

Engine



UDDI Registry

Is an online electronic registry for registering

businesses and Web services

Is a specification for description and discovery

Supports the Publishing and Inquiry APIs topublish and

inquire about a

Web service


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Options for Located Web Service


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UDDI Publishing and Browsing with

Oracle Enterprise Manager

Using Oracle Enterprise Manager Application Server

Control, you can:

Browse and register services within the UDDI

registry

Publish Web services and deploy them to a

Java EE container

Monitor and administer Web services


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Oracle Application Server 10g

Web Services

Oracle Application Server10gWeb Services can beimplemented as any of thefollowing:

Stateless and statefulJava classes

Stateless PL/SQLpackages or Webservices

Stateless sessionEnterprise JavaBeans(EJBs)

Java Message Service(JMS) destinations


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Developing a Web Service

with a Stateless Java Class

To develop a Web service with a stateless Java class,

perform the following steps:

1. Define an interface.

2. Define a stateless Java class.3. Generate an .ear file.

4. Deploy the generated .ear file to Oracle

Application Server 10g.


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Defining an Interface


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Defining a Stateless Java Class


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Creating the Web Service

Invoking JDevelopers

Create Web Service

Wizard


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Examining the Web Service Files


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Deploying the Web Service

Options:

To embedded OC4J

Directly to application server

To WAR or EAR file


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Web Service Home Page

A Web service home page provides:

A link to the service definition (WSDL file)

Links to Web service test pages to test the

available operations of the Web service A link to the Web service client-side proxy JAR

A link to the Web service client-side proxy source


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Testing the Deployed Web Service

with Home Page


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Testing the sayHello Operation


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Exposing and Publishing a PL/SQL

Package as a Web Service


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Summary

In this lesson, you should have learned how to:

Describe a Web service in terms of

Service-Oriented Architecture

Describe that Web services employ a distributedcomponent model, use XML, and are programming

language independent

Create, publish, find, and invoke a Web service

Describe how WSDL is used to define a WS

functionality, how it communicates, and where it isaccessible

Describe how the UDDI registry supports

publishing and inquiry about Web services


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Practice Overview:

Creating a Web Service

This practice covers the following topics:

Developing a Web service

Consuming a Web service


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17_Developing the Business Tier Web Services

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