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Why?
WebServices
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Why Web Services?
“The Web can grow significantly in power and scope
if it is extended to support communication between
applications, from one program to another.”
- From the W3C XML Protocol Working Group Charter
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Presentation Roadmap
Past
Present
Future
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The Hype
New paradigm?
Reason to move platforms?
Replacement for EDI?
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Gartner’s ‘Hype’ Curve 2002
Key: Time to “plateau”
Visibility
Less than two years
Biometrics Grid Computing
Two to five years
Five to 10 years
Natural-language
search Web Services Beyond 10 years
Identity services
Virtual
Personal digital
Wireless private
Nanocomputing assistant phones Text-to- LANs/802.11 networks
speech
E-tags
Speech recognition in
Peer-to-peer call centers
Voice over IP
Personal computing
fuel cells Bluetooth
WAP/ Public key infrastructure
Wireless
Web Location
Speech recognition on desktops
sensing
Peak of
Technology inflated Trough of Slope of Plateau of
trigger expectations disillusionment enlightenment productivity
Maturity
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Gartner’s Hype curve 2016
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W3C (working group) definition
• "A Web service is a software application
identified by a URI, whose interfaces
and bindings are capable of being
defined, described and discovered as
XML artefacts. A Web service supports
direct interactions with other software
agents using XML based messages
exchanged via internet-based protocols."
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What are Web Services?
Identifiedby a URI
Interfaces defined using XML
Can be discovered by other systems
Interact using XML based messages
conveyed by Internet protocols
Source: Web Services Glossary
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What are Web Services?
Application 1 Application 2
XML
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Transport
HTTP POST is most common
But other protocols such as
– FTP
– SMTP
– HTTP GET
And other exotic ones:
– Jabber
– BEEP
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Packaging – Soap
Used to mean
– Simple
– Object
– Access
– Protocol
From SOAP 1.2 > SOAP is no longer an
acronym
Two Types of SOAP
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Packaging – Soap
SOAP RPC:
– encode and bind data structures into xml.
– encode an RPC call
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Serialization
<PurchaseOrder>
<item type=“xsd:string”>
class PurchaseOrder { Serializer socks
String item = “socks”; </item>
int amount = 1; <amount type=“xsd:int”>
} 1
</amount>
</PurchaseOrder>
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Packaging - SOAP
SOAP ‘document style’
– packages xml in an envelope
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Packaging – Soap
HTTP Post
SOAP Envelope
SOAP Head
SOAP Body
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Packaging – Soap
<s:Envelope xmlns:s=“URN”>
<s:header>
<s:transaction xmlns:m=“soap-
transaction”>
<m:transactionID>
1234
</m:transactionID >
</s:transaction>
</s:header>
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Packaging – Soap
<s:Body>
<n:purchaseOrder xmlns:n=“URN”>
<n:item>socks</n:item>
<n:amount>1</n:amount>
</n:purchaseOrder>
</s:Body>
</s:Envelope>
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Description – WSDL
Web Services Description Language
“Web Services Description Language
(WSDL) provides a model and an
XML format for describing Web
services.” w3c.org
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Description – WSDL
Types
Messages
Operations
Encoding
Endpoint
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Types
<types>
<schema targetNamespace=" IMessageService.xsd"
xmlns="…/XMLSchema"
xmlns:SOAPENC="…/soap/encoding/"/>
</types>
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Messages
<message name=“purchase">
<part name=“item" type="xsd:string"/>
<part name=“quantity" type="xsd:integer"/>
</message>
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Operations
<operation name="setMessage">
<input name="setMessageRequest“
message="tns:setMessageRequest"/>
<output name="setMessageResponse“
message="tns:setMessageResponse"/>
</operation>
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Encoding
<soap:operation soapAction="" style="rpc"/>
<input name="setMessage0Request">
<soap:body use="encoded"
namespace="MessageService"
encodingStyle="…/soap/encoding/"/>
</input>
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Endpoint
<service name="MessageService">
<port name="MessageServicePort"
binding="tns:MessageServiceBinding">
<soap:address location="http://localhost:8080/setMessage/"/>
</port>
</service>
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Discovery – UDDI
Universal Description, Discovery and
Integration
A UDDI Server acts as a registry for
Web Services and makes them
searchable.
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Discovery – UDDI
UDDI Registry
Inquiry
Publish
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Discovery – UDDI
UDDI Registry
Inquiry
Publish
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SOAP-based communication
Waiting
Waitingfor for Sending
Sending
requests
requests Data in XML format requests,
requests,
(known location, getting
(known location, getting
known port)
known port)
results
results
• SOAP:
– Data in a well-defined XML format
– Transport over various protocols
• HTTP, SMTP are the most used, perhaps
because they are firewall-friendly
– server side: either an RPC call or a
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Web services
• A collection of XML-based technologies
developed by the e-business community
to address issues of:
– service discovery
– interoperable data exchange and/or
application invocation
– service compositions (workflow, business
processes)
• Major developers include:
– Apache, IBM, HP, SUN & Microsoft (.NET)
• http://www.webservices.org/
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Web Services Architecture
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Web Services Stack
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XML Messaging Using SOAP
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WSDL
• Web Services Definition Language
– http://www.w3.org/TR/wsdl/
• An XML-based language for describing
Web Services
– what the service does (description)
– how to use it (method signatures)
– where to find the service
• It does not depend on the underlying
protocol
• But: It is not much human-readable
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Hello.wsdl
<?xml version="1.0" encoding="UTF-8"?>
<wsdl:definitions
targetNamespace="http://localhost:8080/axis/services/Hello"
xmlns="http://schemas.xmlsoap.org/wsdl/"
xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
xmlns:impl="http://localhost:8080/axis/services/Hello-impl"
xmlns:intf="http://localhost:8080/axis/services/Hello"
xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/soap/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <wsdl:message
name="setHelloMessageRequest"> <wsdl:part name="in0"
type="xsd:string"/> </wsdl:message> <wsdl:message
name="getHelloMessageResponse"> <wsdl:part name="return"
type="xsd:string"/> </wsdl:message> <wsdl:message
name="setHelloMessageResponse"> </wsdl:message> <wsdl:message
name="getHelloMessageRequest"> </wsdl:message> <wsdl:portType
name="HelloWorldService"> <wsdl:operation name="getHelloMessage">
<wsdl:input message="intf:getHelloMessageRequest"/> <wsdl:output
message="intf:getHelloMessageResponse"/> </wsdl:operation>
<wsdl:operation name="setHelloMessage" parameterOrder="in0">
<wsdl:input message="intf:setHelloMessageRequest"/> <wsdl:output
message="intf:setHelloMessageResponse"/> </wsdl:operation>
</wsdl:portType> <wsdl:binding name="HelloSoapBinding"
type="intf:HelloWorldService"> <wsdlsoap:binding style="rpc"
transport="http://schemas.xmlsoap.org/soap/http"/> <wsdl:operation
name="getHelloMessage"> <wsdlsoap:operation soapAction=""/>
<wsdl:input> <wsdlsoap:body
encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
namespace="getHelloMessage" use="encoded"/> </wsdl:input>
<wsdl:output> <wsdlsoap:body
encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
namespace="http://localhost:8080/axis/services/Hello" use="encoded"/>
</wsdl:output> </wsdl:operation> <wsdl:operation
name="setHelloMessage"> <wsdlsoap:operation soapAction=""/>
<wsdl:input> <wsdlsoap:body
encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
namespace="setHelloMessage" use="encoded"/> </wsdl:input>
<wsdl:output> <wsdlsoap:body
CERNencodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
namespace="http://localhost:8080/axis/services/Hello" use="encoded"/>
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UDDI (and alternatives)
• Universal Description, Discovery and
Integration
– http://www.uddi.org
• UDDI creates a platform-independent,
open framework & registry for:
– Describing services
– Discovering businesses
– Integrating business services
• The UDDI may be less used than
predicted, especially on the Internet level
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A Web Service example in Java
HTTP Server
Servlet engine (e.g. Apache Tomcat)
Any
Any
Any class
class
class
Any
Any
processing
Any class
class
class
processing
Any
processing
Any
processing class
class
the
the processing
incoming
processing
incoming
processing SOAP-aware
the
the
the incoming
processing
incoming
incoming SOAP-aware Sending
Sending
requests
the
requests
the incoming
requestsincoming Servlet
the
requestsincoming
requests Servlet requests,
requests,
(“business
(“business
(“business logic”
requestslogic”
requestslogic” (e.g. Apache Axis) getting
(“business
(“business requestslogic”
logic” (e.g. Apache Axis) getting
(“business
(“business logic”
(“business logic” logic” results
results
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Design Recommendations
Create a local class
Create a method with the same name
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Web Services
Future
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Security
WS do not define how to do security,
they rely on other mechanisms
layered on top.
Very common to use SSL
– Good for simple cases
• Weak when multi-tier
• Forces encryption of all data – sometimes
not needed
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Security
Bookstore
Client
Application
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Security Bank
Client Bookstore
Application
Warehouse
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WS Security Standardisation
W3C - http://www.w3c.org
– XML Encryption
– XML Digital Signatures
WS-I - http://www.ws-i.org
– WS Security Profile
OASIS - http://www.oasis-open.org
– WS-Security
– SAML - Security Assertion Markup Language
– XACML - Extensible Access Control Markup
Language
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– XKMS - XML Key Management Specification
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Security – Fire Walls
Bookstore
Client
Application
Fire Wall
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Security
Firewall
‘transparency’
Double-edged sword
– Simplifies deployment
– Opens up potential holes in enterprise
security
• Similar to CGI, etc.
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WS-I
Web Services Interoperability
Organization
http://www.ws-i.org
R1017 A RECEIVER MUST NOT mandate the
use of the xsi:type attribute in
messages except as required in order
to indicate a derived type
WS-I Basic Profile Version 1.0
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Other Statndards
Security
– Single Sign-on, credentials
Transactions
Quality of service
– Timeliness guarantees
Asynchronous operations
– Co-ordination, workflow
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Real Examples
Amazon Web Services API
Google Web API
HP & IBM online stores
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Next Steps
Overtime Interface
Other documents (Materials Request,
TID, Transport Request)
E-Business – with ebXML
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Gartner’s ‘Hype’ Curve
Key: Time to “plateau”
Visibility
Less than two years
Two to five years
Five to 10 years
Beyond 10 years
Web Services
Peak of
Technology inflated Trough of Slope of Plateau of
trigger expectations disillusionment enlightenment productivity
Maturity
CERN Source: Gartner Group June 2002
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Thank you
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