Transcript Web Services

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??