Web Services

Web Services

Name

Title

Department

Company

Learning Objectives

Fundamentals of Web Services Be able to create and debug a Web Service

Using the .NET Framework SDK Using Visual Studio.NET

Agenda

Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous

Web Services OverviewBusiness Today

CEO challenges Revamp customer service Overhaul supply chain Speed up the decision process

CIO challenges Reorient IT architecture Connect with a limitless number of external

constituents Extend processes to external constituents

Web Services Overview Internet Business Processes Span Companies

Web Services Overview Technology Fabric Must Span Companies Too

Companies, suppliers, partners, and customers must be able to work together Faster than ever before Over the Internet Or risk “death by isolation”

Leverage Internet cost structure

Web Services Overview Drivers

Web Services Overview Alternative Solutions

Distributed computing Web sites (portals)

Web Services Overview Distributed Computing

Client/server model Doesn‘t scale Not secure

Distributed object model Components: packaging and interoperability Remoting: remote method invocation COM, CORBA, Java RMI and EJB

Not Internet-friendly Interoperability issues Tightly coupled: still doesn‘t scale

Web Services Overview Distributed Computing

3-tier Application Architecture Great way to build scalable Web applications

But such applications are silos Integration is an afterthought They can be integrated behind the firewall

Even that can be a problem They do not provide a way to integrate across the

firewall (i.e. over the Internet)

Mail

Calendar

News

Finance

Weather

Other

Svcs

Ads

Web Services Overview Portals

No standard way to expose functionality Integration is expensive and error-prone Hard to outsource Not designed to be used outside original scope The problem?

HTML is designed for presentation to people Can’t repurpose it in a general, reliable way Don’t even think about screen scraping

Web Services OverviewPortal Limitations

Web Services Overview What Is a Web Service?

The solution? Web Services! A Web Service exposes functionality to a consumer

Over the Internet or intranet A programmable URL Functions you can call over the Internet

Based on Web standards HTTP, XML, SOAP, WSDL, UDDI

Can be implemented in any language on any platform Black boxes

Component-like, reusable


A Web Service combines the best features of distributed computing and portals and eliminates the worst Provides a mechanism for invoking methods remotely Uses Web standards (e.g. HTTP) to do so


Web Services allow you to interconnect: Different companies Many/any devices Applications Different clients

Not just browsers

Distribution and integration of application logic Enable the programmable Web

Not just the purely interactive Web Web Services are loosely coupled

New paradigm for Internet development Deliver applications as services Richer, customer-driven experience Continuous delivery of value/bits Third-generation Internet


Web Services Overview Evolution of the Web

Generation 1

Static HTML

HTML

Generation 2

Web Applications

HTMLHTML, XML

HTML, XML

Generation 3

Web Services

Web Services Overview Benefits

Everyone Leverage existing infrastructure “Build or buy” development decisions Minimize development time/costs

Enterprises Integration imperative Dynamic, easy B2B relationships

New Web-based businesses Greater personalization New services/new revenue streams Be “everywhere” vs. single destination

Web Services Overview Possibilities

Web Services videos Healthcare Family Business

Web Services

Partner Web Service

Partner Web Service

Data Accessand Storage TierApplication

Business LogicTier Other

Applications

YourCompany.com

Internet + XML

Web Services Overview Application Model

ServiceIntegration

Operations

ServiceDelivery

Development Speed

WebServices Platform

Web Services Overview Sample Web Services

YourCompany.

Com

SOAPWire Formats

WSDLDescription

DiscoDiscovery

Web Services

EmailCalendaring

Instant MessagingNotification

Passport (Authentication)Web Storage System

Credit Card ValidationStock Quotes

Inventory Integration

Agenda


Underlying Technologies XML Is the Glue

Program the Web

XML

Browse the Web

HTML

TCP/IP

Connect the Web

Technology

Innovation

Connectivity PresentationConnecting ApplicationsFTP, E-mail, Gopher

Web Pages Web Services

Underlying TechnologiesOverview

Directoryhttp://www.uddi.org

UDDI

DISCO

WSDL

SOAP

Discoveryhttp://www.ibuyspy.com/ibuyspy.disco

Descriptionhttp://www.ibuyspy.com/ibuyspycs/InstantOrder.asmx?wsdl

Wire Format

Locate a Service

Link to Discovery Document

Request Discovery Document

Return Discovery Document (XML)

Return Service Description (XML)

Return Service Response (XML)

Request Service

Request Service Description

Web

Ser

vice

Clie

nt

UD

DI o

ro

ther

directo

ry service

Web

Service


A Web Service Directory allows potential clients to locate relevant Web Services UDDI

Discovery is the process of locating documents about Web Services located on at a given URL DISCO

A Description language defines the format of methods provided by a Web Service WSDL


The Web Service Wire Format specifies how specific messages are exchanged HTTP-GET HTTP-POST SOAP

HTTP-GET and HTTP-POST use a minimal HTTP interface to invoke Web Services Limited support for data types

SOAP provides a robust HTTP/XML interface Extensive support for data types

XML is designed to represent and transfer structured data In HTML: <p>Jan 15, 2000 </p> In XML: <OrderDate>Jan 15, 2000</OrderDate>

XML does not display or transform data XML separates data from formatting and transforming HTML and XML are both derived from SGML

In different ways

XML OverviewXML Basics

XML is composed of tags and attributes Tags can be nested

Representing entities, entity properties, and entity hierarchy

<ROOT><Orders OrderID="10643" CustomerID="ALFKI" EmployeeID="6" OrderDate="1997-08-25T00:00:00" RequiredDate="1997-09-22T00:00:00" ShippedDate="1997-09-02T00:00:00" />

</ROOT>

XML OverviewXML Syntax

XML schemas describe the structure of an XML document XML schemas describe the tag and attribute

specifications XML schemas also describe constraints on the

contained text XML schemas and the DTD are mutually exclusive

XML OverviewXML Schemas

A lightweight protocol for exchanging information in a distributed, heterogeneous environment It enables cross-platform interoperability

Interoperable OS, object model, programming language neutral Hardware independent Protocol independent

Works over existing Internet infrastructure

SOAP Overview

Guiding principle: “Invent no new technology” Builds on key Internet standards

SOAP = HTTP + XML Submitted to W3C

The SOAP specification defines: The SOAP message format How to send messages How to receive responses Data encoding

SOAP Overview

Objects-by-reference Distributed garbage collection Bi-directional HTTP

Activation Complicated

Doesn’t try to solve every problem in distributed computing

Can be easily implemented

SOAP SOAP Is Not…

SOAPThe HTTP Aspect

SOAP requests are HTTP POST requests

POST /WebCalculator/Calculator.asmx HTTP/1.1Content-Type: text/xml...SOAPAction: “http://tempuri.org/Add”Content-Length: 386

<?xml version=“1.0”?><soap:Envelope ...> ...</soap:Envelope>

SOAP Message

SOAP Envelope

SOAP Header

SOAP Body

Message Name and Data

Headers

Headers

XML-encoded SOAP message name and data

<Body> contains SOAP message name

Individual headers

<Header> encloses headers

<Envelope> encloses payload

Protocol binding headers

The complete SOAP message

SOAPMessage Structure

SOAPSOAP Message Format

An XML document using the SOAP schema:<?xml version=“1.0”?><soap:Envelope ...> <soap:Header ...> ... </soap:Header> <soap:Body> <Add xmlns=“http://tempuri.org/”> <n1>12</n1> <n2>10</n2> </Add> </soap:Body></soap:Envelope>

SOAPServer Responses

Server replies with a “result” message:HTTP/1.1 200 OK...Content-Type:text/xmlContent-Length: 391

<?xml version=“1.0”?><soap:Envelope ...> <soap:Body> <AddResult xmlns=“http://tempuri.org/”> <result>28.6</result> </AddResult> </soap:Body></soap:Envelope>

SOAPEncoding Complex Data

Data structures are serialized as XML:

<soap:Envelope ...> <soap:Body> <GetStockDataResult xmlns=“http://tempuri.org/”> <result> <Description>Plastic Novelties Ltd</Description> <Price>129</Price> <Ticker>PLAS</Ticker> </result> </GetStockDataRseult> </soap:Body></soap:Envelope>

Builds on HTTP Security HTTPS X.509 certificates

Developers / IT choose which methods to expose explicitly

Does not pass application code Firewall-friendly Type safe

SOAPSecurity and Features

DevelopMentor Inc. Digital Creations IONA Technologies PLC Jetform ObjectSpace Inc. Rockwell Software Inc. SAP Compaq

Microsoft Rogue Wave Software Inc. Scriptics Corp. Secret Labs AB UserLand Software Inc. Zveno Pty. Ltd. IBM Hewlett Packard Intel

SOAPIndustry Support

POST /StockQuote HTTP/1.1Host: www.stockquoteserver.comContent-Type: text/xml; charset="utf-8"Content-Length: nnnnSOAPAction: "Some-URI“

<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-URI"> <symbol>DIS</symbol> </m:GetLastTradePrice> </SOAP-ENV:Body></SOAP-ENV:Envelope>

SOAPExample of a SOAP Request

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

<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:GetLastTradePriceResponse xmlns:m="Some-URI"> <Price>34.5</Price> </m:GetLastTradePriceResponse> </SOAP-ENV:Body></SOAP-ENV:Envelope>

SOAPExample of a SOAP Response

HTTP/1.1 500 Internal Server ErrorContent-Type: text/xml; charset="utf-8"Content-Length: nnnn

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"> <SOAP-ENV:Body> <SOAP-ENV:Fault> <faultcode> SOAP-ENV: MustUnderstand </faultcode> <faultstring>SOAP Must Understand Error </faultstring> </SOAP-ENV:Fault> </SOAP-ENV:Body></SOAP-ENV:Envelope>

SOAPExample of a SOAP Error

WSDL is an XML format for describing Web Services Methods, arguments, return values

WSDLWeb Services Description Language

Data Schema Low-level typing for message parameters

Message Format of an individual transmission

PortType Group messages into logical operations

Binding Connect a PortType to an implementation (usually SOAP)

Service Define the physical location of an end point

WSDL WSDL Elements

WSDL Example

Demo: http://localhost/…/math.asmx?WSDL

DiscoveryDISCO

Discovery lets you find Web Services A Web site publishes DISCO documents, which

returns the URLs of WSDL descriptions DISCO documents can contain references to other

sites and DISCO documents Dynamic discovery enables trees of directories to be

searched

UDDI

What is UDDI? Universal Description, Discovery, and Integration A registration database for Web Services

Based on SOAP and XML

Marketplace

UDDIThe Vision

Search Portal

Marketplace

Search Portal

Marketplace

Business Users

Advanced Discovery via Portals and Marketplaces

UDDI Registries and Protocol

Technical Users

UDDIFeatures and Services

Can search by business, service, Web Service (tModel), binding

Drill-down query model Use find_X queries to obtain top-level detail –xLists

Obtain detail using a get_xDetail inquiry

Can update/register business information, services, and bindings Secure!

UDDIExamples of Service Types

RosettaNet PIPs Ariba cXML CommerceOne xCBL Custom APIs (e.g., MSInvoice) Service Services

Microsoft Passport Rating Services Home Page

UDDIService Type Registration

Pointer to the specifications describing the service type What programmers read to understand how to use

the service May be any combination of documents or XML

resources (schemas, WSDL, etc.) Identifier for who published the service Identifier for the service type itself

called a tModelKey Used as a unique signature by Web sites that

implement those services

UDDIService Types

UDDI Business Registry

Service TypeRegistrations

Service Type Publishers

Hosted Service Specifications

Documentation

Resources

Schemas, XSLT

WSDL

Others…

Unique Identifier Descriptions URL for Specifications

UDDIBusiness Registration

Holds all of the information in UDDI related to a single business or business unit

It is the “master container” Organization hierarchy not defined in V1

businessKeynameURLdescriptioncontactsbusinessServicesidentifierBagcategoryBag

businessEntitykeyedReference

tModelKeykeyNamekeyValue

keyedReference


keyedReference


keyedReference


businessService

tModelKeyNameDescriptionBindingTemplates

businessService

tModelKeyNameDescriptionBindingTemplates


Contact

PhoneAddressEmail


Contact

PhoneAddressEmail

UDDIExample of a Registration

BindingTemplate5E2D412E5-44EE-…http://www.sydneynet/harbour…tModelInstanceDetails

tModelInstanceInfo

4453D6FC-223C-3ED0…

http://www.rosetta.net/catalogPIP

keyedReference

DFE-2B…D-U-N-S9876545231

keyedReference

EE123…NAICS0241722

tModelKeys

businessEntityTB993… Harbour Metalswww.harbourmetals.co.au“Serving Inner Sydney Harbour for …contactsbusinessServicesidentifierBagcategoryBag

23T701e54683nf…Online catalog“Website where you can …BindingTemplates

businessService

872-68914281 King’s Blvd, Sydney, [email protected]

Peter Smythe

UDDISoftware Development Kit

Available from http://uddi.microsoft.com COM components and API for interacting with

the UDDI registry Hides XML and SOAP behind objects

UDDI envelope UDDI message

Sample application UDDI Explorer, written with Visual Basic 6.0

Agenda


Developing a Web Service Basics

Web Service source files Implemented in ASP.NET Similar to Web Forms, but have a .asmx file

extension Lives in a virtual directory Can have a code-behind Can use .NET Framework classes and custom

assemblies and classes

Developing a Web Service Code and Syntax

Codebehind

Inline (in C#)

<%@ WebService Language="c#" Codebehind="MyWebService.cs"

Class="FirstWebService.MathService" %>

<%@ WebService Language=“C#“ Class=“MathService“ %>

using System.Web.Services;public class MathService : WebServices { [WebMethod] public int Add(int num1, int num2) { return num1 + num2; }}

Developing a Web Service Demo

Demo: HelloWorld.asmx Demo: MathService.asmx

Developing a Web Service Tools

Notepad Just create a .asmx file

Visual Studio.NET Create ASP.NET Web Service project

Developing a Web Service Publishing Web Services

Expose Web Services and Web Methods Create a Web Service proxy and an assembly

wsdl.exe Create an assembly Enables developers to program against Web Services

Publishing WSDL contracts and HTML description

Developing a Web Service Discovery of Web Services

.disco file XML-based file containing links to resources Stored in the server‘s root directory Access via URL and Dynamic discovery document Start discovering a URL with wsdl.exe

Disco http://terraserver.microsoft.net

Global directory through UDDI Universal, Discovery, Description and Integration

(http://www.uddi.org)

Visual Studio.NET Automatically creates .disco file

Agenda


Consuming Web ServicesOverview

Locate the desired Web Service UDDI DISCO

Get detailed description of Web Service WSDL

Create a proxy that represents the Web Service Proxy has the same methods/arguments/return

values as the Web Service Application instantiates and uses the proxy as if

it were a local object


Web ServiceDeveloper Web Application

Developer

Web Server 1

Service Appasmx .aspx

Web Server 2

Service Application

Proxy Web Form


Web Services are URL addressable HTTP request/response

Invoking via: HTTP-GET

Method name and arguments HTTP-POST HTTP-SOAP

XML grammar for: Addressing the Web Service Returning results

Consuming Web Services Invoking: HTTP-GET and POST

HTTP-GET

Result is an XML document

http://localhost//MathService.asmx/Multiply?a=11&b=11

<?xml version="1.0" encoding="utf-8" ?> <int xmlns="http://www.microsoft.com/MathService/">121</int>

Consuming Web Services Invoking: HTTP-GET and POST

HTTP-POST

POST /MathService.asmx/Multiply HTTP/1.1 Host: localhost Content-Type: application/x-www-form-urlencoded Content-Length: length

a=string&b=string

Consuming Web Services Invoking: HTTP-SOAP

XML grammar for WebMethod, Method parameter, results

Supports all standard .NET datatypes and value classes Additionally: classes, structs, datasets

Class and struct marshalling Serialization in XML format

Consuming Web Services Type Marshalling

Using HTTP-GET or HTTP-POST Primitive types Enum types Arrays of primitives and enums By-value only

Consuming Web Services Type Marshalling

Using SOAP Primitive types Enum types Classes and structs DataSet XmlNode Arrays of all of the above By-value and by-reference are supported

Consuming Web ServicesTrying It Out

Request without method name or parameters ASP.NET returns a page listing all methods

Click one of the methods and you can test it out

Specify parameters and Invoke Only for primitive data types

Sample requests/responses

http://localhost/MathService.asmx

http://localhost/MathService.asmx?op=Multiply

Consuming Web ServicesTrying It Out

Request with parameter “WSDL” Formal WSDL description of Web Service XML-based grammar Can be used as input for wsdl.exe

http://localhost/MathService.asmx?WSDL

Consuming Web ServicesDemo

Demo: MathService.asmx

Consuming Web ServicesCreating a Proxy

Use wsdl.exe to generate a proxy

Creates MathService.cs Contains MathService class, derived from SoapHttpClientProtocol in the System.Web.Services.Protocols namespace Or HttpGetClientProtocol or HttpPostClientProtocol

You can instantiate these classes dynamically Proxy embeds URL to the Web Service in the

constructor

wsdl http://localhost/MathService.asmx?WSDL

Consuming Web ServicesDiscovery

Use disco.exe to discover Web Services on a specific machine

disco http://localhost

Consuming Web ServicesUsing Visual Studio.NET

Use Add Web Reference to search UDDI or to discover Web Services given a URL

This builds a proxy, and you can start using the Web Service immediately Visual Studio.NET essentially calls disco.exe and wsdl.exe for you

Agenda


MiscellaneousState Management

Web Services are stateless Use ASP.NET session state mechanism

What is a session? Restricted to a logical application Context in which a user communicates to a server

Functionality Request identification and classification Store data across multiple requests Session events Release of session data

.NET State Server Process

MiscellaneousSecurity Model

Reasons for security Prevent access to areas of your Web server Record and store secure relevant user data

Security configuration Authentication, Authorization, Impersonation

Code Access Security Are you the code you told me you are?

WebClient

OS

ASP.NETAppIIS

.NET

WebService

RMIService

DCOMService

Client

Firewall

Port 80

MiscellaneousHTTP and Firewalls

WebService

Client

WebService

Client

Raw HTTP

SSL

<soap:Body> <AddResult xmlns= ...> <result>28.6</result> </AddResult></soap:Body>

<soap:Body> <AddResult xmlns= ...> <result>28.6</result> </AddResult></soap:Body>

MiscellaneousSecure Sockets Layer

MiscellaneousSecurity Model

Similar to securing a Web site Clients are computers and businesses

Possible options with IIS IPSec Basic Basic over SSL Digest Integrated Client certificates Passport?

Like ASP.NET Web Forms COM+ services

COM+ automatic transactions atomic, consistent, isolated, durable (ACID)

MiscellaneousTransactions

MSMQ Server

SQL Server

Application

COM+transaction context

Web Service

MiscellaneousTransactions

[WebMethod(Transaction= Transaction.Required)]

Transaction modes Supported NotSupported Required RequiresNew

MiscellaneousExecution Model

Synchronous Like any other call to class methods

Asynchronous Split the method into two code blocks

BeginMethodName EndMethodName

CLR determines if operation has finished

MiscellaneousHailStorm

What is HailStorm? A set of Web Services that make it much easier to

integrate existing information Oriented to people, instead of to a specific device,

application, service, or network

MiscellaneousHailStorm Services

myAddress - electronic and geographic address for an identity myProfile - name, nickname, special dates, picture myContacts – electronic relationships/address book myLocation - electronic and geographical location and rendezvous myNotifications – notification subscription, management, and routing myInbox - inbox items like e-mail and voice mail, including existing

mail systems myCalendar – time and task management myDocuments – raw document storage myApplicationSettings - application settings myFavoriteWebSites – favorite URLs and other Web identifiers myWallet - receipts, payment instruments, coupons, and other

transaction records myDevices – device settings, capabilities myServices –services provided for an identity myUsage – usage report for above services

MiscellaneousHailStorm Availability

The initial set of HailStorm services is scheduled to be available in a broad developer beta in late 2001, with full release in 2002.

An SDK for building Web Services using Visual Studio 6.0 Components allowing an ASP page to act as a facade

for a COM object Wizard for generating WSDL descriptions from COM

servers Client-side engine for dynamically creating an

Automation proxy from WSDL

MiscellaneousSOAP Toolkit

Available at http://msdn.microsoft.com/downloads/default.asp?URL=/code/sample.asp?url=/msdn-files/027/001/580/msdncompositedoc.xml

Easily expose COM components as Web Services through SOAP and schemas

Client infrastructure for Visual Studio Focused on one way of creating Web Services


Remote Object Proxy Engine (ROPE) A set of COM components you can use to build SOAP

messaging into your application Client-side infrastructure to build Web Services Server side infrastructure Greatly simplifies SOAP programming You can use SOAP without using ROPE


Conclusion


Resources

Web Services Essentialshttp://msdn.microsoft.com/library/default.asp?URL=/library/techart/webservicesessentials.htm

SOAPhttp://msdn.microsoft.com/soap/

SOAP Specification http://www.w3.org/TR/SOAP/

Resources

Don Box on SOAP http://msdn.microsoft.com/msdnmag/issues/0300/soap/soap.asp

Introduction to SOAPhttp://www.w3.org/2000/xp/Group/Admin/minutes-oct1100/soap-xp-wg_files/frame.htm

WSDL Specificationhttp://www.w3.org/TR/wsdl/

Resources

A Quick Introduction to WSDLhttp://msdn.microsoft.com/library/default.asp?url=/library/en-us/soap/htm/soap_overview_72b0.asp?frame=true

UDDIhttp://www.uddi.orghttp://uddi.microsoft.com

HailStormhttp://www.microsoft.com/net/hailstorm.asp

Resources

Building Web Services with SOAP and ASP.NEThttp://msdn.microsoft.com/msdnmag/issues/01/02/WebComp/webcomp.asp

Web Services

Documents

Transcript of Web Services