Introduction to Web Services in the Microsoft 'Net Framework

1
Introduction to Web Servicesin the Microsoft
.Net Framework
2
Contents

• Introduction to Web Services
• Introduction to Web Services in the Microsoft
  .Net Framework
• A Web Services Example Microsofts .NET My
  Services
• Creating a Web Service in Visual Studio .Net
• Consuming a Web Service in Visual Studio .Net

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Introduction to Web Services
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Defining Web Services

• A web service is a chunk of functionality that
  can be accessed using web technology
• Across an intranet or the Internet
• Usually
• Whats accessed is a method in a language such as
  Java or Visual Basic.NET
• The web technology used is the Simple Object
  Access Protocol (SOAP) carried over HTTP
• Both the .NET and Java camps have endorsed web
  services

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Key Web Services Technologies

• Web Services Description Language (WSDL)
• An IDL for web services
• Simple Object Access Protocol (SOAP)
• An XML-based protocol for web services
• Universal Description, Discovery, and Integration
  (UDDI)
• A directory service for web services

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Illustrating Web Services Technologies
UDDI Registry
Internet
UDDI Registry
Application
Application
Application
WSDL Interface
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Applying Web Services (1)

• Connecting clients to Internet applications
• One example is Microsofts .NET My Services
• B2B integration on the Internet
• The next generation of EDI
• Enterprise application integration (EAI) on
  intranets
• A standard approach to connecting all applications

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Applying Web Services (2)
Internet
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Describing Web Services WSDL

• Created by Microsoft and IBM
• Recently handed to the World Wide Web Consortium
  (W3C)
• Endorsed by everybody
• Microsoft, IBM, Sun, Oracle, BEA, more

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Accessing Web Services SOAP

• The Simple Object Access Protocol (SOAP) allows
  invoking operations
• SOAP defines an XML-based format for parameters
• SOAP requests/responses can ride on
• HTTP
• The most common case today
• SMTP or MSMQ
• For loosely-coupled interactions
• Other protocols

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What SOAP Provides

• Industry agreement
• Its endorsed by Microsoft, IBM, Sun, Oracle,
  BEA, Iona, and others
• Object model independence
• SOAP isnt tied to any operating system,
  programming language, or object model
• Support for diverse protocols
• Synchronous and asynchronous

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Illustrating A SOAP Message
Envelope
Headers
Body
Method
Parameters
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An Example SOAP Request (1)

• POST /AccountAccess HTTP/1.1
• Host www.qwickbank.com
• Content-Type text/xml charsetutf-8
• Content-Length 305
• SOAPAction
• ltSOAP-ENVEnvelope
• xmlnsSOAP-ENV
• "http//schemas.xmlsoap.org/soap/envelope/"
• SOAP-ENVencodingStyle
• "http//schemas.xmlsoap.org/soap/encoding/"gt

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An Example SOAP Request (2)

• ltSOAP-ENVBodygt
• ltmGetBalance
• xmlnsm"http//www.qwickbank.com/bank"gt
• ltAccountgt729-1269-4785lt/Accountgt
• lt/mGetBalancegt
• lt/SOAP-ENVBody gt
• lt/SOAP-ENVEnvelopegt

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An Example SOAP Response (1)

• HTTP/1.1 200 OK
• Content-Type text/xml charset"utf-8"
• Content-Length 304
• ltSOAP-ENVEnvelope
• xmlnsSOAP-ENV
• "http//schemas.xmlsoap.org/soap/envelope/"
• SOAP-ENVencodingStyle
• "http//schemas.xmlsoap.org/soap/encoding/"gt

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An Example SOAP Response (2)

• ltSOAP-ENVBodygt
• ltmGetBalanceResponse
• xmlnsm"http//www.qwickbank.com/bank"gt
• ltBalancegt3,822.55lt/Balancegt
• lt/mGetBalanceResponsegt
• lt/SOAP-ENVBody gt
• lt/SOAP-ENVEnvelopegt

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Discovering Web Services UDDI

• Universal Description, Discovery, and Integration
  (UDDI) provides a specialized directory service
  for discovering compatible web services
• It uses XML
• Its endorsed by Microsoft, IBM, Ariba, Oracle,
  Sun, BEA, and more
• An organization can create an XML-defined
  business registration
• Which can contain information about various
  available web services

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Illustrating A UDDI Business Registration
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The Trouble With UDDI (2000)

• Its complicated
• Microsofts .NET Framework ships a simpler
  discovery mechanism called Disco for use on
  intranets
• Its not being used for web services yet
• Many businesses are registered, but not many WSDL
  definitions
• Without WSDL, developers cant build
  interoperable web services clients

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Introduction to Web Services in the Microsoft
.Net Framework
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ASP.NET

• The next generation of ASP (Active Server Pages)
• It looks similar, but its actually very
  different
• Allows creating two kinds of applications
• Browser applications
• Rely on .aspx pages
• Web services applications
• Rely on .asmx pages

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Illustrating a Web Services Application
IIS
class X WebMethod public int Method1()

SOAP
app.asmx
ADO.NET
Common Language Runtime
DBMS
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Exposing Web Services An Example .asmx Page (1)

• lt_at_ WebService Language"c" Class"Compute" gt
• using System.Web.Services
• public class Compute
• WebMethod public int Factorial(int f)
• int i
• int result 1
• for (i2 iltf i)
• result result i
• return result

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Exposing Web Services An Example .asmx Page (2)

• WebMethod public double SquareRoot(double s)
• return System.Math.Sqrt(s)

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XML Web Services Protocol Stack
Internet Protocols
Directory of services UDDI
Service discovery DISCO
Microsoft specific ?
Service descriptions WSDL
Service interactions SOAP
Universal type system XSD
Universal data format XML
Ubiquitous communication Internet
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Web Services
Application Concepts
Data
Schema
Services
Invocation
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Web Services with .NET
public class OrderProcessor WebMethod
public void SubmitOrder(PurchaseOrder order)
... XmlRoot("Order", Namespace"urnacme.b2b
-schema.v1") public class PurchaseOrder
XmlElement("shipTo") public string ShipTo
XmlElement("billTo") public string BillTo
XmlElement("comment") public string Comment
XmlElement("items") public Item Items
XmlAttribute("date") public DateTime
OrderDate
public class OrderProcessor public void
SubmitOrder(PurchaseOrder order) ... public
class PurchaseOrder public string ShipTo
public string BillTo public string Comment
public Item Items public DateTime
OrderDate
lt?xml version"1.0" encoding"utf-8"?gt ltsoapEnvel
opegt ltsoapBodygt ltSubmitOrdergt ltOrder
date"20010703"gt ltshipTogtManuel
Costalt/shipTogt ltbillTogtBill
Gateslt/billTogt ltcommentgtOvernight
deliverylt/commentgt ltitemsgt
ltproductIdgt17748933lt/productIdgt
ltdescriptiongtDom Perignonlt/descriptiongt
lt/itemsgt lt/Ordergt lt/SubmitOrdergt
lt/soapBodygt lt/soapEnvelopegt
Order order new Order() order.ShipTo "Manuel
Costa" order.BillTo "Bill Gates" order.OrderDa
te DateTime.Today OrderProcessor.SubmitOrder(
order)
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A Web Services Example Microsofts .NET My
Services
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A Web Services Example Microsofts .NET My
Services

• .NET My Services is a set of Internet-accessible
  web services that store data about users
• The data is described using XML
• Applications can access that data
• Access is via SOAP
• Users control which applications are allowed to
  access which parts of their data

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Illustrating .NET My Services
.NET My Services
Internet
Clients
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Describing .NET My Services

• Passport
• Based on Kerberos
• .NET Alerts
• .NET Services
• .NET Contacts
• .NET Locations
• .NET Calendar
• More

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A .NET My Services Request
SOAP request - Service name - PUID -
Kerberos ticket - Method(Parameters)
.NET My Services Applications
.NET My Services
SOAP response
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.NET Services (Mark)
.NET Contacts (Mark)
Passport Service
.NET Services (Bob)
Booking Application
.NET Alerts (Bob)
.NET Locations (Bob)
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Creating a Web Service in Visual Studio .Net
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Creating a ASP.NET Web Service Project
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Changing the Web Service Name
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Accessing the Code Behind
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Understanding the Code Behind
inheritance is optional (useful to create state
full web services)
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Editing the Code Behind
attribute that tells that this method should be
exposed as a web service method
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Understanding the .asmx page
In this case, everything is in the code behind
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Build
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Files Generated
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Testing with a Browser
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Viewing the dynamically generated WSDL (1)
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Viewing the dynamically generated WSDL (2)
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Consuming a Web Service in Visual Studio .Net
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Creating a ASP. NET Web Application
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Adding a Reference to the Web Service
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Viewing the Proxy Class Created Behind the Scenes
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Designing the web page
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Calling the web service
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Running the client application
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Sources

• Seminário "Understanding .Net", David Chappell,
  FEUP, 2000
• Seminário "Introduction to .NET", Manuel Costa,
  FEUP, 2001