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Web Services
By Ethan
Justin
Yuli
Web Services in Action
What do Web Services offer
developers, businesses and
consumers?
www.Maps.Google.Com
Information through Integration
(Google Example)
Web Services in Action (continued)

Google.com
– Google Web APIs service gives you query access to Google's web
search, giving developers access to billions of web documents that
are constantly refreshed
– Developers receive results as structured data, can access
information in the Google cache, and check the spelling of words
– Examples of use:
• Issuing regularly scheduled search requests to monitor the web for new
information on a subject
• Performing market research by analyzing differences in the amount of
information available on different subjects over time
• Searching via non-HTML interfaces, such as the command line, pagers,
or visualization applications
• Creating innovative games that play with information on the web
Web Services in Action (continued)

Amazon.com
– Add thousands of products available through
Amazon.com to your own website and earn
referral commissions for sales
– List hundreds of thousands of products on your
site available through Amazon.com affiliates and
customize the content so products match the
theme of your web site
– Dynamically maintain product listings to give
visitors current information
Presentation-Outline

Topics
– SOAP and REST
– WSDL
– UDDI

Summary
 Questions
Web Service-Overview

Web services facilitate the automated
transfer of information from Computer A to
Computer B using the XML language.
 This can be accomplished in a number of
ways, but for today we’re focused on
‘Standards’ based approaches
Web Services- Two Approaches
There is a division in the web
community about the best method for
accessing resources over the internet.
 The two leading methods are SOAP, a
standards-based approach, and REST

Web Services-SOAP
Standards Based Approach
Definition: Simple Object Access
Protocol
 Function: SOAP is an envelope that a
request for resources is packaged in. It
includes a header and body.

– The header can include information about
security, recipients, handling, routing, etc.
– The body includes a standard XML request
Web Services-REST
Non-Standards Based Approach
Definition: Representation State
Transfer
 Function: REST is an architectural style
for accessing distributed media or
resources.

Summary of REST and SOAP

REST
– Messages are represented
in plain XML
– HTTP is used for the transfer
protocol
– HTTP verbs are used for
access/manipulation
commands
– URIs are used to uniquely
identify resources in message
– HTTP authentication provides
security
– There is no formal method for
expressing the interface
contract

SOAP
– Messages are represented in a
standardized XML SOAP
"envelope"
– Can be bound to various
protocols including HTTP and
SMTP
– Access to and manipulation of
data are application specific
– Security is not described by
SOAP and is to be provided by
the developer
– XML schemas or DTD are used
to define the contract between
client and service
Web Services Description Language (WSDL)

WSDL is a language for describing the
capabilities of Web services
– In order for computer A to request information from
computer B it must know the appropriate method
for “asking the question”
– Essentially, a WSDL document describes how to
invoke a service and provides information on the
data being exchanged, the sequence of messages
for an operation, protocol bindings, and the
location of the service.
– WSDL is an integral part of UDDI, an XML-based
worldwide business registry
Web Services-UDDI
(Yellow Pages for Web Services)


Definition: Universal Description Discovery and
Integration
Function: The UDDI specifications define a registry
service for Web services and for other electronic and
non-electronic services. A UDDI registry service is a
Web service that manages information about service
providers, service implementations, and service
metadata.
– Service providers can use UDDI to advertise the services
they offer.
– Service consumers can use UDDI to discover services that
suit their requirements and to obtain the service metadata
needed to consume those services.
Key Topics to Remember

Summary
– WSDL: Standards-Based Description
language for making resource requests
– SOAP: Standards-Based Envelope for
delivering the request
– REST: Messages are represented in plain
(pure) XML only
– UDDI: Voluntary registry for listing and finding
web services (Yellow Pages)
Questions??