Web Services

The Next Dimension of Enterprise Computing

Dr. Billy B. L. LimSchool of Information Technology

Illinois State University

Outline

Web Services What Why How Who When Not

Questions Assuming that you’re a venture capitalist:

Would you fund a company that proposes to build xyzBooks.com and compete directly with the Amazon.com’s of the world?

Assuming that you’re a IT168/177 student: Would you be able to write an app that

gather user addresses and plot a map that shows the route from ISU to the closest address?

E-Commerce Scenarios

Objective: Capitalize on the success of e-commerce and build a web site to sell books, CDs, and others

Scenario1 Build BillyBooks.com and compete

directly with the Amazon.com’s of the world

Any chance of success here?

E-Commerce Scenarios Scenario2

Source: Atkin, J., “Amazon Everywhere,” PC Magazine, 9/2003.

What are Web Services? W3C 2003:

“A Web service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP-messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards.”

Why Web Services? Observations

“I couldn’t make DCOM work. I tried and failed, again and again. But I can make a Web service in a heartbeat.”

-- Jim Gray, Microsoft Distinguished Engineer (Turing Award (~= Nobel Price for computing)

Winner)

Explosive Growth of API Calls / WS

Reference: http://www.slideshare.net/jmusser/open-apis-state-of-the-market-2011

Why Web Services? Observations

Projected Revenues 380 millions in 2001 vs. 15.5 billions in 2005 (Source:

ZapThink, Inc. ’02)

IDC estimate: 1.6 billions in 2004 vs. 34 billions in 2007 (Source: South China Morning Post, May 28, ’02)

0

20000

40000

60000

80000

100000

120000

140000

160000

2001 2005

Revenues

Why Web Services? Observations

“When do you expect your company to develop a Web Services strategy?”

Source: InfoWorld Web Services Survey, July ‘01

now / 3mos

4-6 mos

7-12mos

>=12mos

Never

???

Why Web Services? Observations

The industry is aligned … Broad industry initiative for Web services

Over 150 industry leaders Interoperability across platforms, applications,

and languages

www.ws-i.org

Why Web Services? Observations

Why Web Services? Observations

Technology of the Year (InfoWorld ’02)

Why Web Services?

Interoperable Easy to use Reusable Ubiquitous

OS Services

BrowsersBrowsers

ServersData, Hosts

ServersData, HostsUI Logic

Biz Logic

1st Generation Web Applications

Source: Gusmano ‘02

OS Services

Biz LogicTier

Biz LogicTier

Rich Client UI Logic

Rich Client UI Logic

ServersData, Hosts

ServersData, Hosts

Richer Browsers

Richer Browsers

2nd Generation Web Applications

Source: Gusmano ‘02

StandardBrowsers

StandardBrowsers

SmarterClients

SmarterClients

SmarterDevices

SmarterDevices

Open Internet Communications Protocols

(HTTP, SMTP, XML, SOAP)

Applications Become Programmable Web Services

OS Services

BizTier Logic

BizTier LogicBiz Logic & Web Service

OSServices

OSServices

Public WebServices

Foundation Services

InternalWeb Services

XML

XML

XML

ServersData, Hosts

ServersData, Hosts

XML

Other Services XML

XML

XML

HTML

Next Generation Web Applications

Source: Gusmano ‘02

Web Services: Life Cycle

Service Provider (e.g., Brokerage House)

Service Registry (e.g., IBM UDDI service)

Service Requester (e.g., XYZ Financial Software) bind to service

find service publish service (e.g., stock quote)

Life Cycle of a Web Service Execution (Registry, Lookup, and Consumption)

What is Under the Hood?

XML SOAP WSDL UDDI

Web Services: SOAP, WSDL, UDDI

An Overview of SOAP Simple Object Access Protocol Lightweight XML-based messaging format Builds on

W3C XML standards IETF HTTP standard

Works with: Any operating system Any programming language Any platform

SOAP MessageSOAP Message

SOAP Envelope

SOAP HeaderSOAP Header

SOAP BodySOAP Body

Message Name & Data

Headers

Protocol Headers

XML Encoded SOAP Message Name and Data

<Body> contains SOAP Message Name and Data

Individual headers

<Header> encloses headers

<Envelope> encloses payload

Standard Protocol (HTTP, SMTP, etc.) and SOAP Headers

The complete SOAP Message

What is a SOAP Message?

POST /StockQuote HTTP/1.1 Host: www.stockquoteserver.com Content-Type: text/xml Content-Length: 323 SOAPAction: “www.stockquoteserver.com/GetLastTradePrice”

<?xml version=“1.0” encoding=“utf-8”?>

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP-ENV:Body> <m:GetLastTradePrice xmlns:m="Some-Namespace-URI"> <symbol>DIS</symbol> </m:GetLastTradePrice> </SOAP-ENV:Body></SOAP-ENV:Envelope>

Simple SOAP Request (Using HTTP)

HTTP/1.1 200 OKContent-Type: text/xml; charset=utf-8Content-Length: nnnn

<?xml version=“1.0” encoding=“utf-8”?>

<SOAP-ENV:Envelopexmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP-ENV:Body> <m:GetLastTradePriceResponse

xmlns:m="Some-Namespace-URI"> <Price>24.5</Price> </m:GetLastTradePriceResponse> </SOAP-ENV:Body></SOAP-ENV:Envelope>

Simple SOAP Response (Using HTTP)

WSDL

Web Services Description Language Lets Web Services describe

what they are where they can be found how they should be used

<?xml version="1.0"?>

<serviceDescription>

<soap >

<service>

<addresses>

<address uri="http://localhost//HelloWorld.asmx"/>

</addresses>

<requestResponse name="HelloWorld" soapAction="http://tempuri.org/HelloWorld">

<request ref="s0:HelloWorld"/>

<response ref="s0:HelloWorldResult"/>

</requestResponse>

</service>

</soap>

</serviceDescription>

Simplified WSDL example

Complete one: Complete one: ISU Hello in Foreign Language Translator

UDDI

Universal Description, Discovery, and Integration

Lets companies find publicly available Web Services on the Internet or corporate Intranets.

UDDI

Web services: Some possibilities Financial information (e.g., stock quotes) Sports information Weather information News Delivery status Tax and shipping calculations Any data that is relevant to the client

How useful are Web Services?

Web Services: Who? Who is doing this?

Vendors Microsoft, IBM, Sun, Oracle, HP, BEA, etc. .NET passport, Calendar, Alerts, Amazon Web

Services, etc.

Users/Consumers Nordstrom, General Motors, etc. List of public Web Services http://www.xmethods.net/

Who should pay attention to this? All of us!

Web Services: When?

Web Services: When? Web Services will enter most organizations in three

distinct phases: [Source: IDC] 2002 (within the firewall)

Simplified app integration Increased developer productivity

2004 (contained external users) Simplified business-partner connectivity Richer app functionality Subscription-based services

2006 to 2008 (fully dynamic search and use) Casual / ad-hoc use of services New business models possible Commoditization of software Pervasive use in nontraditional devices

Web Services: The Not? Challenges/Issues

Reliability / Consistency Security Authentication Privacy Billing Reuse Performance Incompatible implementations of standards

Web Services: “Lingua Franca”

Source: Clarke ‘02

References Clarke, N., “.Net & the J2EE: Web Services - Can we live together?,” JavaOne

2002. Gosling, J., Next-Generation Web Services Conference, Keynote address,

Jan, 2002. Gusmano, M., “Build Web Services with VB.NET,” Microsoft Internet

Developer Group, April 2001.