m. adel serhani

8/3/2019 M. ADEL SERHANI

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WEB SERVICE REVOLUTION: TRENDS ANDCHALLENGES

SECOND KUWAIT CONFERENCE ON E-SERVICES AND E-SYSTEMS

M. ADEL SERHANIFACULTY OF INFORMATION TECHNOLOGY

UAE UNIVERSITY

Outline Tutorial Objectives

Part I: Overview of Web Services Concepts

Introduction to SOA

On Demand Business

Main SOA standards: WSDL, SOAP, UDDI, and XML

Service Oriented architecture SOA and Business Challenges

Architectu ral features of SOA: the Webservice Gateway and the EnterpriseService Bus (ESB)

How to implement my fi rst Web Service

Using Netbeans. Web Service Composition

Business Process

BPEL

Service Integration

How to implement my first BPEL processusing Netbeans

Restful Web Services

REST Design Pattern

Restful Architecture

Restful vs. Web service

How to implement my first Restful

Web service using Netbeans.

Part II: Web Service Tools,

Development Platforms and

Applications

Web Services Development Platforms.

Web Services Tools.

Real world applications and casestudies.

Resources: References and online

resources.

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Tutorial Objectives

To learn the current state of the art in Web services, contrast and present tools

and techniques for the development of standard and RESTful Web services.

To acquire advanced concepts related Service Oriented Architecture (SOA)

and their standards.

To understand technologies those are involved and/or must be developed to

realize the advanced concepts.

To grasp the potential of Web service compositions.

To discuss and debate the main research challenges in Web services and SOA

adoption.

To learn detailed step-by-step examples of how to program Web services

both SOAP and Restful Web services in Java. And to learn how to build a BPEL composition process.

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The On Demand business

IBM defines an on demand business as an

enterprise whose business processes,

integrated end-to-end across the company

and with key partners, suppliers, and customers,

can respond with speed to any customer

demand, market opportunity, or external threat.

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An on demand business must be:

Responsive can sense and respond to the market

Variable can adapt processes and cost structures

to reduce risk

Focused concentrates on its core business, not

infrastructure

Resilient manages changes and external threats

while keeping its constituents happy.

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The idea behind (Web) services

If youve got some code that does something useful

(an EJB or a legacy application, for example), you

can make that code available as a (Web) service.

Ejb, Legacy

Runtime wrapperSOAP, RMI, Java

Design time wrapperWSDL

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Web Services

A Web service is an implementation of well-defined business

functionality

Are published, found and used through the Web.

It is promoted as a new way to build network applications from

distributed components that are language- and platform-

independent.

Help simple web applications publish their functions on the web

and make them available for integration with other applications.

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Web Service Sample Scenario

Consumer of Web Services

Inventory client:

Connect to Web Service

Query

Order

Ship

Deliver

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Web Service Sample Scenarios (Cont.)

Consumer of Web Services

Road traffic information client

Connect to query conditions

Review options

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Web Services Basics

What You Should Know

HTML

XML

What are Web Services

Web services are application components

Web services communicate using open protocols

Web services are self-contained and self-describing

Web services can be discovered using UDDI

Web services can be used by other applications

XML is the basis for Web services

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Web Services as a Business Asset

Combination of content, application code, process logic

Represented by an XML object

SOAP (Simple Object Access Protocol) protocol

WSDL (Web Services Description Language) description

UDDI (Universal Description, Discovery and Integration)registration

Standards based

Can be shared, combined, used, reused

Supporting heterogeneous users, organizations, firms

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Main Uses

Reusability

Help create web-based components that are used by several

applications

Examples:

Currency conversion, weather reports, language translation,

etc.

Integration

Allows different applications to exchange their data (even

when they are implemented in different platforms andprogramming tools).

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Web Services Standards

JSR-101 (Web Services)

SOAP Definition

Lightweight protocol

XML based

Message elements

Envelope - defines framework fordescribing message contents

Processing options

Encoding rules data types,conventions, remote procedurecalls

Not suitable for pervasivedevices

Due to Resource demands

JSR-172 (J2ME Web Services)

Defines a standard interface to WebServices

Targets for J2ME platform

CDC and CLDC based profiles

Access to remote SOAP / XML basedWeb Service

Parsing XML data (optional)

Minimal memory footprint

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Web Service Protocols

transport

network

messaging

service description

service discovery

application

UDDI (Universal Description, Discovery,

and Integration)

WSDL (Web Service Description Language)

XML, SOAP (Simple Object Access Protocol)

TCP, HTTP, SMTP, Jabber

IP

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UDDI

UDDI - Universal Description, Discovery, and Integration

protocol.

UDDI is a directory service where businesses can

register and search for Web services.

A directory for storing information about web services

A directory of web service interfaces described by WSDL

Communicates via SOAP

OASIS driven standardization effort

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UDDI Query and Response Example

The following query, whenplaced inside the body ofthe SOAP envelope, returnsdetails on Microsoft.

Microsoft

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Microsoft Corporation

Empowering people through great software -any time, any place and on any device is Microsoft'svision. As the worldwide leader in software for personaland business computing, we strive to produce innovativeproducts and services that meet our customer's

Web s ervices for smart searching

Electronic Business Integration Services..

Query Response


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WSDL

WSDL - Web Services Description Language:

WSDL is an XML-based language for describing Web

services and how to access them.

Written in XML as an XML document

Used to describe Web services

Used to locate Web services

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WSDL Skeleton

A WSDL document can be divided into six major elements

: Root WSDL Element

: What data types will be transmitted?

: What messages will be transmitted?

: What operations will be supported?

: How will the messages be transmitted

on the wire?

: Where is the service located?

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SOAP

SOAP - Simple Object Access Protocol:

A protocol for communication between applications

Platform independent and language independent

Simple and extensible

Applies XML for message exchange in support of remote method calls

(invocations) over the Internet (using HTTP).

Compared to remote method invocation and CORBA-based facilities:

SOAP is web-based or wired thus is not subject to firewall restrictions

SOAP is language-independent

SOAP can provide just-in-time service integration

SOAP is developed as a W3C standard

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SOAP Building Blocks

A SOAP message is an ordinary XML document containing the

following elements:

A required Envelope element that identifies the XML document as a

SOAP message

An optional Header element that contains header information

A required Body element that contains call and response information

An optional Fault element that provides information about errors thatoccurred while processing the message

All the elements above are declared in the default namespacefor the SOAP envelope

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SOAP Messages

message body

SOAP body

header block

header block

SOAP header

SOAP envelope

optional

req

uired

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Skeleton SOAP Message

SOAP Response:

Toptimate 3-PieceSet

827635

3-Piece luggage set. Black

Polyester.96.50

true

SOAP Request:

827635

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What is an SOA?

Architecture that leverages open standards to

represent software assets as services

Provides a standard way of representing and

interacting with software assets

Individual software assets become building blocks that

can be reused in developing other applications

The preferred method of building an SOA is (Web)services.

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Ordering at a Restaurant Diagram

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Craig Duncan

Calling a Web service diagram28

Craig Duncan


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S.O.A

SOA uses the find-bind-executeparadigm

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Benefits of SOA (I)

Applications can be built that are: Platform-independent

Distributed

Secure

Web services will become the common architecture forsystem and application integration Based on open industry standards

Companies and government agencies will be able toeasily communicate with customers and externalpartners


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Benefits of SOA (II)

Loosely-coupled and flexible systems are more usefulthan hard-wired and monolithic ones: Example World Wide Web

Service Oriented Architecture (SOA)

Companies and government agencies will be able toaccess software remotely that they or others havealready built (reuse)

Organizations will be able to extend the life andvalue of legacy systems by exposing existing data as

XML

More reasons to use Web services

Developers will be able to integrate applications: Quickly Easily Inexpensively

Software development and maintenance time will bereduced Increase efficiency 30% Gartner

Data can be secured using industry standard security

methods: Secure Socket Layer (SSL) protocol Public-key certificates WS-Security


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Two Important Concepts in SOA

SOAs are designed to integrate everything in your

enterprise.

Not everything understands SOAP, and not everything is

accessible by HTTP.

The Web services gateway and the Enterprise

service bus are two important architectural features

of an SOA.

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Web Services Gateway

A Web services gateway is an intermediary

between a SOAP client and a service that doesn't

have a SOAP interface.

A Web service gateway is a front-end to another

type of service. It has two interfaces:

One that understands SOAP

One that understands the native protocol (or languageor data format and so forth) of the service.

Web serviceclient

Web servicesgateway

Legacyapplication

SOAP???

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The Web Services Gateway

ClientWeb Svcs.Gateway

SOAP

Service

Local JavaService

JMS

Service

JCAService

CICS

Service

WSDL URL,method name,

methodparameters

protocol-specificdetails

The Gateway:

Takes requests from Webservice clients

Figures out where the

requests should go

Handles the details of

getting it there.

It might convert a SOAPrequest to an MQ message,

for example.

It is an implementation of the

delegate pattern.

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Managing Interoperability

You can get significant business value from a point-

to-point Web service:

Java client Java service

J2EE application

Packaged apps

B2B service

COBOL system

But what happens

when you have multiple

services?

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Managing Interoperability

With multiple clients and services, complexity

becomes a big issue

we need something to simplify this.


.NET client J2EE application

Packaged apps

B2B service

COBOL system

COBOL client

Perl client

Python client

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The ESB

IBMs vision is for the Enterprise Service Bus to

handle message routing between Web services.

EnterpriseService

Bus


J2EE application

Packaged apps

B2B service

COBOL system

.NET client

COBOL client

Perl client

Python client

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The ESB

With the ESB, the requestors job is to build a

request according to the services WSDL.

Remember, this might use something other than SOAP,

something other than HTTP, and so forth.

The ESBs job is to figure out how to get the request

to the service, then get the response to the

requestor.

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How to implement my first Web Service using Netbeans

Install Netbeans version 9.6.1 available under the following link: http://netbeans.org/ , Install the full

version that include the Glassfish Server.

Make sure that a java (JDK) is installed on your computer if not download it from:

http://www.oracle.com/technetwork/java/javase/downloads/index-jdk5-jsp-142662.html

Copy and unzip the file MyFirstWS file to a folder your create on your computer call it

MyFirstWSProject.

Open Netbeans IDE, then open a project from the folder above and use the file MyFirstWS.

Deploy/Run the project and Test the Web service.

Extend the Web service implementation by adding new methods: Multiplication, and division methods.

Redeploy/Run the project and test the new updated Web service.

Cerate another Web Service under the same project call it TimeWS.

Cerate the corresponding methods: methods that returns the time, date, year, etc.

Redeploy /Run the project and test the new Web service.

Try to extend your project by using other web services you created or those available online.


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Business Processes

No one implements an SOA without a businessjustification.

Flexible business processes are the ultimate goal ofan SOA. (On Demand!)

Business experts define the flow of a process (tasks,exceptions, data flows, and so forth).

Developers then associate the steps in the processwith resources.

Business experts and developers can work togethermuch more closely.

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Problem

To achieve a given objective sell my car, I may

need more than one Web Service:

Car Valuation service WS1

Car Auction Service WS2

Online Financial service WS3

All three WS need to interact seamlessly

To achieve my goal

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Web Services Composition

Composed Web Services are:

Individual components implemented at different places

Execute in different contexts

But, need to communicate to yield desired behavior

Multiple approaches based on perspective:

StaticDynamic WS composition

Synchronous and Asynchronous

Industry solution Semantic Web solution

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Composition of Web Services: Synchronous

ClientService

CreditService

InventoryService

PurchaseOrder

InvoiceConsolidate

Results

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Composition of Web Services: Asynchronous

ClientService

CreditService

InventoryService

PurchaseOrder

InvoiceConsolidate

Results

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BPEL

The Business Process Execution Language (BPEL)

defines a business process as a set of tasks.

BPEL is a high-level XML-based language for

stringing Web services calls (and other things)

together.

We can export our business process model as a BPEL

file.

BPEL makes it easy to change the way the process flows.

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BPEL: Core Concepts

Peer-to-peer synchronous/asynchronous messageexchanges Request-response One way (e.g., notification, reply to callback interface) Sequence vs. parallel flow

Data handling: variables, property definition, dataextraction and assignment

Data-dependent behavior (conditional and timeoutconstructs)

Exception handling and recovery Cross-partner coordination (message correlation) Scope (group a set of activities)

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BPEL Example

Business Process Execution Language

Introduction to Web Services Technologies

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Examples of Web Service composition implementation50

Netbeans SOA Tools, Composite Application, CASA

http://www.youtube.com/watch?v=a76RxkzB4Bg&feature=BF&list=QL&index=2

Oracle BPEL - Hello World Example

http://www.youtube.com/watch?v=XRzTySj-aak

Eclipse Web Service Composition

http://www.youtube.com/watch?v=q2PvBUev0Mk&feature=related


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What is REST?

REST stands for REpresentation State Transfer

A proven architectural style for building loosely-coupled, highly-scalable applications

REST is about accessing resources through a universalinterface

Conceived in 2000 as a doctoral dissertation by RoyFielding (a principal author of HTTP protocol).

NOT a standard You will not see the W3C putting out a REST specification.

You will not see IBM or Microsoft or Sun selling a REST developer's toolkit.

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REST defined

Resources are identified by uniform resource

identifiers (URIs)

Resources are manipulated through their

representations

Messages are self-descriptive and stateless

Multiple representations are accepted or sent

Hypertext is the engine of application state

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REST Characteristics

Client-server

Stateless

Cached

Uniform interface

Layered system

Code on demand: Java script code can be loadedfrom the server to be executed by the browser.

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RESTful Implementation

Resources: Web Servers

Representation: Web pages

URI:

Web site address which is uniquely identified

Standard verbs like GET, PUT, POST, DELETE

Guess what?

All functions on the Web has till date been done with the use ofthese standard verbs

These verbs are general enough

State: Stateless interactions, as each hyperlink gets anew representation which changes client state

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RESTful Architecture State

Resource

Representation

Unique Identification

Client1

Resource

Clientn

Representation

http://www.worldstock.com/MycroSoft/RateToday

RateToday.html

The Representation sent from the Resource transfers the state of the client.

Hence, Representational State Transfer (REST)

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RESTful Architecture (Cont.)

State

State is the representation of the values of the properties of a resource

Clients state changes when a representation is received from a resource

Resource

The source of information

All requests to resources must be stateless containing all the information necessary for that request without dependency on

previous requests

Representation

The information received from a source (resource): Can take differentformats

Unique Identification (URI: Uniform Resource Identification) Nouns, which identify what is required (e.g. Patient, Students )

Communication via a standardized interface Standard Verbs, which identify what is the action (e.g. Give, Remove....)

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RESTful Web Services Every Resource can be identified by a URI

Defined as nouns and NOT verbs

http://UAEU/student/a122233

http://UAEU/students?name=sam

The resources are requested through HTTP Request

The representation is received as HTTP Response

Representation is got through standard interface (HTTP verbs)

GET : Retrieve

PUT : Update

POST : Create

DELETE : Delete

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RESTful Web Services

So why should we build Web services using REST?

REST leverages well know internet standards

The necessary infrastructure has already become pervasive

HTTP clients and servers available for all possible platforms

Inexpensive and very low adoption barrier

REST sees HTTP as an application level protocol

HTTPS provides the level of security

URLs provide unique identification and service description

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SOAP vs. REST

REST web services are:

Lightweight - not a lot of extra xml markup

Human Readable Results

Easy to build - no toolkits required

SOAP also has some advantages:

Easy to consume - sometimes

Rigid - type checking, adheres to a contract

Development tools

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SOAP vs. REST

What the experts say

Each has its place

One cannot replace the other

REST is a good choice for exposing data while SOAP for

exposing logic

REST is simpler and can be used for applications on the

Internet while SOAP can be used for enterpriseapplications

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REST applications The famous Twitter API is all REST.

Yahoo! offer most of their services using REST. Thisincludes Search API,

Maps,

Photos,

Traffic,

... and just about any other.

Amazon.com offer several REST services, e.g., for theirS3 storage solution

Atom is a RESTful alternative to RSS.

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RESTful Web Services Challenges

Absence of RESTful Web service Registry to allow:

Service providers to publish information about their services

Clients to look for these services

Absence of service description information (e.g.operation detail and parameters) to allow client tosearch within the service itself.

WADL is emerging but yet not rich enough.

Restful Web services does not adhere to a compositionscheme.

...

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How to implement my first Restful Web Service using Netbeans

Copy and unzip the file MyFirstRESTWS file to a folder your create on yourcomputer call it MyFirstRESTWSProject.

Open Netbeans IDE.

Open Netbeans IDE, then open a project from the folder above and use the fileMyFirstRESTWS.

Deploy/Run the project and Test the Web service

Extend the Web service implementation by adding new methods: Multiplication,and Division methods.

Redeploy/Run the project and test the new updated Web service.

Cerate another Web Service under the same project call it TimeWS

Cerate the corresponding methods: methods that returns the time, date, year, etc.

Redeploy/Run the project and test the new Web service.

Try to extend your project by using other web services you created or thoseavailable online.


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Web Service Development Platforms

Platforms:

Sun J2EE (Netbeans, Eclipse, etc.)

IBM WebSphere

Microsoft .NET Framework

Oracle SOA Suite (Weblogic, JDeveloper, )

Management Frameworks:

IBM Tivoli (Integrated Service Management Software)

HP OpenView (Service Management Framework)

...

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Web Service organizations

Standards organizations: World Wide Web Consortium (W3C) Web Services Interoperability Organization (WS-I) Organization for the Advancement of Structured Information Standards

(OASIS)

Vendors: Microsoft IBM Sun Microsystems

Companies exposing data as Web services: Amazon.com Google

Companies writing Web services for theaviation industry C3D Aero

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Web Service Tools

SOAP Engine

Apache AXIS

WSDL Editor

WSDL Designer

soapUI

XMLSpy

SOAPAgent

Crispy UDDI4J

Gomba

IBM alphaWorks Web Services Tools

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Real World applications

Healthcare

Connect Healthcare Enterprise using SOA

Mobile Web services for Health Monitoring

Habitat Monitoring and Green Building (Sensors + Web

Services)

AC, Light, Door monitoring and control

Marriage of Web services and Sensor Networks

Mobile Web Services

Traffic information

Digital Maps (Google Maps API Web Services)

Attraction services

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Summary

Web Services provide controlled access to back-endapplications

Minimal devices can still consume web services

SOA drive the new trends in Service/Application Integration

Web Services expand your applications reach.

Web Service composition explore the full potential of WebServices.

Restful Web Service leverages well know internet standards. Restful Web Services A proven style for building loosely-coupled,

highly-scalable applications

Web Services Toolkit eases programming access to WebServices.

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References and resources used to develop this Tutorial

Francis Geysermans, IBM Tutorials, Service-oriented Architecture briefing,http://ibm.com/developerworks/offers/techbriefings/presentations/webservices.html

Craig Duncan, How Web Services Work, C3D AERO http://www.c3daero.com/presentations/HowWebServicesWork.ppt

Michael Stollberg and Armin Haller DERI Digital Enterprise Research Institute, Semantic Web Services Tutorial, ICWS2005.

http://javasoa.com/

http://www-01.ibm.com/software/solutions/soa/

http://www.alphaworks.ibm.com/webservices

http://ws.apache.org/

Java Web Serv ices Tutorial For Java Web Services Developer's Pack, v2.0:http://java.sun.com/webservices/docs/2.0/tutorial/doc/

RESTful Web Service Tutorial: http://rest.elkstein.org/2008/02/roa-vs-soa-rest-vs-soap.html

John Cowan, An introduction to building Web Services without tears (without SOAP or WSDL), http://www.ccil.org/~cowan

Web Services Tutorial: http://www.w3schools.com/webservices/

SOAP Tutorial: http://www.w3schools.com/soap/default.asp

Apache SOAP: http://www.ibm.com/developerworks/library/ws-peer2/

Apache SOAP for Java: http://www.soapuser.com/client2.html

BPEL Tutorials: http://soa.netbeans.org/soa/ Examples of Web services from (www.webservicex.net) and from NetBeans (http://netbeans.org/kb/trails/web.html)

Open Source Web Services Tools in Java (http://java-source.net/open-source/web-services-tools)

.

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