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eCommerce Technology
20-751
Lecture 14:
Web Services
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Machine-to-Machine M2M Commerce
• There are more machines than people
• Machines are always becoming more functional
(Moore’s law)
• Intelligent agents exist
• More commerce will be occur between machines
than between people
• Commerce machines must discover each other and
be able to do business (common language)
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Human Web v. Transactional Web
• They’re the same hardware, different software
• WWW was designed to be accessed by humans
– browsers
• Protocols needed to allow machines to access
information
• Need to run software resident on other systems and
networks
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
B2B Much More Complicated Than B2C
Choose
Vendor
B2C
B2B
Review
Catalogs
Identify
Specifications
Define
Requirements
Letter of
Credit / Terms
Process
Credit
Card
Select
& Order
Send
RFP
Select
Vendor
Approve
P.O.
Fill Out
P.O.
Review
Vendors
Prepare
Fulfillment
Ship
Set Up
Credit
Send P.O.
to Vendor
Generate P.O.
Receipt
Check
Availability
Send
Invoice
Send
Order
Inspections
Receive
Order
Prepare
Invoice
Receive Invoice /
Prepare Payment
Arrange
Shipping
Tariffs /
Customs
Post
Payment
Send
Check
SOURCE: METALSITE
Web Services
• Self-contained, self-describing applications
• Created using familiar programming languages (Java)
• Published, located and invoked over the Web using
Web service interface standards
• By machines
• Function may be very simple or very complicated
• Examples:
–
–
–
–
a foreign currency converter
stock quotations, analysis
product recommender agent
freight forwarder
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Example: Shopping Cart Checkout
Discount
Calculation
Shopping
Cart
Tax
Calculation
Services may reside
somewhere else,
provided by someone else
Shipping
Calculation
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Web Services Example

A Buyer Service is ordering goods from a Seller Service.

The Seller Service may need to use other web services to accept
and process the order
2
VALIDATE
Credit
Validation
Service
1
ORDER
OUT
IN
BUYER
SERVICE
SELLER
SERVICE
IN
OUT
3
GOODS
SOURCE: HEATHER KREGER, IBM
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Public v. Private Workflows
Buyer
Service
Seller
Service
Public Flow
Private Flow
IN
Credit
Validation
Service
Public
Credit
Service
Inventory
Management
Service
Customer
Accounting
Service
OUT
Step 1 Step 2 Step 3
SOURCE: HEATHER KREGER, IBM
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Six Properties of a Web Service
• IBM definition:
object-oriented
– self-contained
– self-describing
– modular applications
– published
WSDL
WEB SERVICES
DESCRIPTION LANGUAGE
– located
UDDI
UNIVERSAL DESCRIPTION
DISCOVERY AND INFORMATION
– invoked across
the web
SOAP or XML-RPC
SOURCE: OBJECTIVE SOLUTIONS
20-751 ECOMMERCE TECHNOLOGY
SIMPLE OBJECT
ACCESS PROTOCOL
SUMMER 2002
XML REMOTE
PROCEDURE CALL
COPYRIGHT © 2002 MICHAEL I. SHAMOS
UDDI Summary
1.
4.
Companies, standards
bodies, and programmers
populate the registry with
descriptions of different
types of services
Marketplaces, search
engines, and business
apps query the registry
to discover services at
other companies
2.
UDDI Business Registry
Businesses
populate
the registry
with
descriptions of
the services
they support
Business
Registrations
5.
Service Type
Registrations
3. UBR assigns a unique identifier to each
service and business registration
SOURCE: UDDI.ORG
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
Business uses this
data to facilitate
easier integration
with each other
over the Web
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Publishing and Using Web Services
UDDI Registry
Service
Description
(WSDL)
White
Yellow
WSDL
Descriptions
Web Service Provider
Publish
Green
Find
Web
Service
Business
Function
Web
Server
Application
Server
WSDL
Client
Function
Stub
WebServices Client
Bind +
Business Methods
SOURCE: HEATHER KREGER, IBM
Web Services In Action
Find a web service provider (UDDI)
http://www.uddi.org
UDDI
Link to WSDL document
Web
Service
Consumer
How do we talk? (WSDL)
http://myservice.com?wsdl
Service descriptions
Let’s talk (SOAP)
http://myservice.com/service
XML/SOAP body
SOURCE: SIMON HUTSON, KPMG
Web
Service
Provider
Simple Web Services Workflow

A Buyer Service is ordering goods from a Seller Service.

The Seller Service interface is defined using WSDL.


Buyer Service invokes the “order” method on the seller service
using SOAP and the WSDL definition for the seller service.
The Buyer Service knows what to expect in the SOAP reply
message. This is defined in the Seller Service WSDL.
ORDER
OUT
IN
BUYER
SERVICE
SELLER
SERVICE
IN
OUT
GOODS
SOURCE: HEATHER KREGER, IBM
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Architectural Overview
• Web service is a standards-based façade
• Wrapper for accessing non-standardized applications
HTTP
XML Response
Web
Service
HTTP
middleware
XML Request
Listener
Web Server
Business
Service
• Web services are invoked by sending text files over
HTTP
SOURCE: OBJECTIVE SOLUTIONS
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Invoking a Web Service
•
•
•
•
Client queries a UDDI registry node
Server returns a list of records matching request
Client identifies a specific service of interest
Server “binds” client to the service so client can invoke
the methods of the service
MACHINE
Client
application
MACHINE
SOAP
processor
Web
server
UDDI registry
service
SOAP request
SOAP response
UDDI
registry
node
UDDI
database
SOURCE: OBJECTIVE SOLUTIONS
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Simple Object Access Protocol (SOAP)
•
•
•
•
•
•
SOAP demo
UDDI demo
Amazon search
Google search
Digital signature demo
xmethods.com
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Types: xSchema definition of data
Service
Port
Binding
Port Types
Operations
Messages
Types
<types>
<schema
targetNamespace="http://example.com/stockquote.xsd"
xmlns="http://www.w3.org/2000/10/XMLSchema">
<element name="TradePriceRequest">
<complexType>
<element name="tickerSymbol" type="string"/>
</complexType>
</element>
<element name="TradePrice">
<complexType>
<element name="price" type="float"/>
</complexType>
</element>
</schema>
</types>
SOURCE: FRANK ROBINSON. SILVERSTREAM
Messages: Collections of Types
Service
Port
Binding
Port Types
Operations
Messages
Types
<message name="GetLastTradePriceInput">
<part name="body" element="xsd1:TradePriceRequest"/>
</message>
<message name="GetLastTradePriceOutput">
<part name="body" element="xsd1:TradePrice"/>
</message>
SOURCE: FRANK ROBINSON. SILVERSTREAM
Operations: Available Methods
Service
Port
Binding
Port Types
Operations
Messages
Types
<operation name="GetLastTradePrice">
<soap:operation
soapAction="http://example.com/GetLastTradePrice"/>
<input>
<soap:body use="literal"/>
</input>
<output>
<soap:body use="literal"/>
</output>
</operation>
SOURCE: FRANK ROBINSON. SILVERSTREAM
Port Types: XML Method I/O
Service
Maps Operations to Messages
Port
Binding
Port Types
Operations
<portType name="StockQuotePortType">
<operation name="GetLastTradePrice">
<input message="tns:GetLastTradePriceInput"/>
<output message="tns:GetLastTradePriceOutput"/>
</operation>
</portType>
Messages
Types
SOURCE: FRANK ROBINSON. SILVERSTREAM
Binding: Maps Protocols to Methods
Service
Port
Binding
Port Types
Operations
Messages
<binding name="StockQuoteSoapBinding“
type="tns:StockQuotePortType">
<soap:binding style="document“
transport="http://schemas.xmlsoap.org/soap/http"/>
<operation name="GetLastTradePrice">
<soap:operation
soapAction="http://example.com/GetLastTradePrice"/>
<input>
<soap:body use="literal"/>
</input>
<output>
<soap:body use="literal"/>
</output>
</operation>
</binding>
Types
SOURCE: FRANK ROBINSON. SILVERSTREAM
Port: Maps URLs to Methods
Service
Port
<port name="StockQuotePort" binding="tns:StockQuoteBinding">
<soap:address location="http://example.com/stockquote"/>
</port>
Binding
Port Types
Operations
Messages
Types
SOURCE: FRANK ROBINSON. SILVERSTREAM
Service: Packages Ports & Bindings
Service
Port
<service name="StockQuoteService">
<documentation>My first service</documentation>
<port name="StockQuotePort"
binding="tns:StockQuoteBinding">
<soap:address
location="http://example.com/stockquote"/>
</port>
</service>
Binding
Port Types
Operations
Messages
Types
SOURCE: FRANK ROBINSON. SILVERSTREAM
Web Service Definition Language (WSDL)
• A WSDL file contains details in XML about provider
(server) services
• For each service, WSDL describes the set of allowed
operations
• For each operation, WSDL describes the formats of
messages exchanged between the requesting consumer
(client) and the provider (server)
– to request the service; and
– to interpret the results (output) of the service
SOURCE: ELIOT CHRISTIAN, USGS
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
WSDL Contains Details About Services
SOURCE: ELIOT CHRISTIAN, USGS
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
WSDL Contains Details About Operations
SOURCE: ELIOT CHRISTIAN, USGS
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
WSDL Contains Details About Messages
SOURCE: ELIOT CHRISTIAN, USGS
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
SOAP Mechanisms
• Request and Response messages
– request invokes a method on a remote object
– response returns the result of the method execution
• Messages wrapped in a SOAP envelope
– SOAP envelope is an XML grammar
– Message grammar is different from envelope
Application Message
(Application-Specific
grammar)
SOAP Envelope
(SOAP grammar)
SOURCE: JEZ WAIN, BULL
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
SOAP Request
POST /weather HTTP/1.1
Standard
Host: www.meteo.fr
Content-Type: text/xml
http Header
Content-Length: <nnn>
SOAP header
SOAPAction: http://www.meteo.fr/meteo#getWeather
Extensions
<SOAP:Envelope xmlns:SOAP="urn:schemas-xmlsoaporg:soap.v1.1">
<SOAP:Body>
<m:getWeather xmlns:m=”meteo.xsd">
<location>Grenoble</location>
</m:getWeather>
Xml
Payload
</SOAP:BODY>
</SOAP:Envelope>
SOURCE: JEZ WAIN, BULL
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
SOAP – Writing a Service
package meteo;
public class MeteoServer {
public MeteoServer() {
private HashMap weathermap = new HashMap;
weathermap.put(“Grenoble”, “sunny and warm”);
weathermap.put(“London”, “cold and wet”);
}
public String getWeather(String location) {
String weather;
if ((weather = (String)weathermap.get(location))!= null) {
return new String(“the weather in “ + location +
“ is “ + weather + “ as usual”);
} else {
return new String(“Can’t find “ + location + “ on the map”);
}}}
SOURCE: JEZ WAIN, BULL
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Example: Notification Service
Message
Sender
Notification
Service
publishMessage
subscribe
unsubscribe
Message
Subscriber
Service
receiveMessage
Subscriber
List
APIs:
publishMessage()
subscribe()
unsubscribe()
…
Topic
Subscriber Reference
WS\A\B
<wsdlURL>#<port>
WS\C\D
<wsdlURL>#<port>
…
…
SOURCE: IDC
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Example: Utility Services
…
…
XXX
Service
Service
Service
Register
Subscribe
Drive
Demo
Identity
Service
Service
Requestor Identity
Check
DigSig
Handler
Identity
Servlet
DigSig
SOAP
Message
Contract
Service
Check
Usage
Contract
Identity
Handler
Contract
Handler
Notification
Service
Message
Logging
All Published Service
Messages
Metering
Request
Handler
Store IdentityKey
In MessageContext
Business
Service
Create,
Update,
Query
Data
Common
Data
Service
Metering
Response
Handler
Record
Meter Event
Metering
Service
SOURCE: IDC
Provisioning
Service UI
Generate
Report
Get Meter
Events
Accounting
Service
Provisioning
Service UI
Web Services Vision
• Applications become process flow & event management
• Processes are just sets of object method invocations
• Object can:
–
–
–
–
Exist anywhere
Be owned by anyone
Be developed anyhow
Execute on any platform
• Applications use methods as needed
– Discover them through UDDI
– Negotiate their use dynamically
– Bind to & execute them in real time
SOURCE: IDC
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Timeline for Web Services Adoption
2002
Within
the
firewall
2004
Contained
external
users
2006
2008
Fully dynamic search & use
SOURCE: IDC
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS
Q&A
20-751 ECOMMERCE TECHNOLOGY
SUMMER 2002
COPYRIGHT © 2002 MICHAEL I. SHAMOS