Creating & Consuming Web Creating & Consuming Web ServicesServices

MIS 424

Professor Sandvig

Overview – Web ServicesOverview – Web Services

What are Web Services?What are Web Services?

BenefitsBenefits

Who is using themWho is using them

Using in .NETUsing in .NET– How to createHow to create– How to consumeHow to consume

What are Web Services?What are Web Services?

Web services allow applications to communicate Web services allow applications to communicate with each other via Internetwith each other via Internet

Islands of dataIslands of data

Huge databasesHuge databases– Every large organizationEvery large organization– Can’t communicate, shareCan’t communicate, share

Between organizationsBetween organizations

Within organizationsWithin organizations

What are Web Services?What are Web Services?

Underlying TechnologiesUnderlying Technologies– XMLXML

Defines data contentDefines data content– SOAPSOAP

Simple object access protocolSimple object access protocol– Protocol Protocol rules rules

AdvantageAdvantage– HTTP: name-value pairsHTTP: name-value pairs– SOAP: SOAP:

data relationshipsdata relationshipsData typesData types

Both are W3.org standardsBoth are W3.org standards– Supported by all major vendorsSupported by all major vendors

Why Now?Why Now?

HistoricallyHistorically– Physical distancePhysical distance– Small data pipelinesSmall data pipelines

NowNow– Internet, fiber optics, …Internet, fiber optics, …– Distance not a problemDistance not a problem

Recent: mid-1990’sRecent: mid-1990’s

LimitationLimitation– Need common language & protocolsNeed common language & protocols

SolutionSolution– Web Services: XML & SoapWeb Services: XML & Soap

Who is using?Who is using?

AmazonAmazon– Retrieve shipping infoRetrieve shipping info– Expose product databaseExpose product database

UPSUPS– Shipping status, pricing information, etc.Shipping status, pricing information, etc.

GoogleGoogle– Expose databaseExpose database– Tap creativity of programmersTap creativity of programmers

Ideas for freeIdeas for free

Others??Others??– Difficult to tell, background processDifficult to tell, background process

Overstock.com web site

Using Web Services in .NETUsing Web Services in .NET

Web Service NamespacesWeb Service Namespaces– Implements XML & SOAP technologiesImplements XML & SOAP technologies– Dozens of classesDozens of classes

High levelHigh level

Handle messy detailsHandle messy details

– MSDN DocumentationMSDN Documentation

Heavily promoted functionality of .NETHeavily promoted functionality of .NET

Using Web ServicesUsing Web Services

Two roles:Two roles:– CreateCreate

Expose your data/application to otherExpose your data/application to other

– ConsumeConsumeUtilize web services offered by othersUtilize web services offered by others

Creating Web ServicesCreating Web Services

Visual Studio:Visual Studio:– Add new item: Web ServiceAdd new item: Web Service

.asmx file.asmx file

Creating Web ServiceCreating Web Service

Default .asmx file:

Creating Web ServicesCreating Web Services

Example:Example:

TestingTesting– Via HTTPVia HTTP

Request .asmx fileRequest .asmx file

– CreateWebService.asmx, (source .doc)CreateWebService.asmx, (source .doc)

Consuming Web ServiceConsuming Web Service

Create proxyCreate proxy– Visual StudioVisual Studio

1.1. Add service reference…Add service reference…2.2. Paste in web service Paste in web service

description language (wsdl)description language (wsdl)– VS creates classes that utilize VS creates classes that utilize

serviceservice

3.3. Use like any other classesUse like any other classes

Consuming Web ServiceConsuming Web Service

Visual StudioVisual Studio

Paste web Paste web service URLservice URL

Consuming Web ServiceConsuming Web ServiceWSDL returns service description:WSDL returns service description:– Give descriptive name and click OKGive descriptive name and click OK

Consuming Web ServiceConsuming Web Service

Visual Studio creates class Visual Studio creates class (proxy) representing web (proxy) representing web serviceservice

Adds info to web.config Adds info to web.config

Consuming Web ServicesConsuming Web Services

Service now represented by classService now represented by class

Service methods visible via IntellisenseService methods visible via Intellisense

Consuming Web ServiceConsuming Web Service

Example: Example: – ConsumeWebService.aspxConsumeWebService.aspx

– .asmx files can handle AJAX calls.asmx files can handle AJAX callsSee assignment 4 See assignment 4

– ObjectDataSource control:ObjectDataSource control:Use VS wizard to select web service classUse VS wizard to select web service class

Summary – Web ServicesSummary – Web Services

Allow applications to communicateAllow applications to communicate– Connect islands of dataConnect islands of data

Based upon W3 standardsBased upon W3 standards

.NET support.NET support– Very easy to publish & consumeVery easy to publish & consume