Web Services
By:
Anushi Goel
1
Overview
What is Web Service
Motivation for web Services
Web Services Architecture
Future Vision and Challenges
2
What Is Web Services
Example: Web based
purchase
reeddiitt e
Cr ocnks
C
ReC
shpe Credit
Service
Purchase Consolidate
Invoice
Order Results
InR
v
PO Service RIen eensteo
svpe rrvye
onnt
sery
o
Web services are self contained, self describing, modular applications
that can be published, located, and invoked across the web. Web
services perform functions, which can be anything from simple requests
3
to complicated business processes".
---- According to IBM
Features Of Web Services
Search / Use
Integration
Description
Service
Service
Directory
Service
Virtual Travel
Agency
Pu
bl
is
Description
h
Service
B
Migration Of Existing web Application
B2
Service
Standards are the Base
Description
B Communicate using messages
B2
Robust , Effective, Flexible Security
B2B
Services Description
Web Service Discovery
4
Benefits of Web Service
Create a single, comprehensive, flexible Web platform
Utilization existing Infrastructure
Web services gives users the option of choosing a particular
hardware and software platform without being concerned about
the integration cost.
Content management systems to store information in a repository
where it is easily accessible for reuse
Traditional security mechanisms have given way to "entitlement
programs"
5
Web Services Meet Business Processes
Sales Finance
Web Web
Service 1 Service 4
Logistics HR
Web Web
Service 2 Service 5
Support Partners Support
Web Web
Service 3 Service n
6
Network
Network
How widespread they are today?
“IDC report, nearly 50% of enterprises interviewed will have implemented Web
services by 2006. IDC estimates that 5% of all U.S. enterprises had completed Web
Services initiatives by the end of 2002, and it projects that 80% will have some kind
of Web services project underway by 2008”
“Gartner expects Web services will dominate the deployment of new application
solutions for Fortune 500 companies by 2004”
“Approximately 79% of companies surveyed in the summer of 2002 planned to
implement a Web services project in 2003, according to the Software & Information
Industry Association (SIIA) and Systinet Corp.,”
“To not explore investing in some type of Web services initiative at this point would
be a mistake. There's a distinct need today for application interoperability, which is
the goal of Web services."
says Laurie A. Seymour, a program manager at research firm IDC.
Web services "are becoming extremely important, extremely fast," says Whit
Andrews, an analyst in research firm Gartner's Internet platform and Web services
group.
7
Web Services Architecture
Architecture can be described in terms of
• What goes “on the wire”:
Formats and protocols.- XML, SOAP, and WS-Addressing
• What describes what goes on the wire:
Description languages.- Machine-readable metadata
• What allows us to find these descriptions:
Discovery of services- Web service discovery
• What protocols to use to transport
• Specification for enumeration of service resources
12
XML-eXtensible Markup Language
In Web services, a message is an XML document information item as defined
by the XML Information
The Information items generally maps to the various features in an XML
document, such as elements, attributes, namespaces, and comments ….
.
There are eleven types of information items in an XML document.
It allows opaque binary data to be interleaved with traditional text-based
markup. The W3C XML-binary Optimized Packaging (or XOP) format.
SOAP Message Transmission Optimization Method, or MTOM, then specifies
how to bind this format to SOAP
XOP and MTOM are the preferred approach for mixing raw binary with text-
based XML
13
SOAP- Simple Object Access Protocol
SOAP provides a simple and lightweight mechanism for
exchanging structured and typed information between peers in a
decentralized, distributed environment using XML
Contains three elements: <Envelope>, <Header>, and <Body>.
SOAP Node, original sender , ultimate receiver, intermediary, message
path.
Message Exchange Patterns: Broadcast transports , Push Model,
Pull Model
Transport Independence: using HTTP , SOAP-over-UDP
14
Metadata
Metadata enables interoperability.
Describe the message interchange formats the service can support
Web Service Description Language, or WSDL, was the first widely
adopted mechanism for describing the basic characteristics of a Web
service.
WSDL may define where the service is available and what
communications protocol is used to talk to the service.
WS-Policy introduces a simple and extensible grammar for expressing
policy
15
Discovery
Two most common approaches to finding information in a computer
system: looking in a well-known location, or broadcasting a
request to all available listeners.
The Universal Description, Discovery, and Integration protocol, or
UDDI, specifies a protocol for querying and updating a common
directory of Web service information.
UDDI directory approach can be used when Web service information
is stored in well-known locations.
Microsoft, IBM and SAP host the UDDI Business Registry.
Directory entry has three primary parts – the service provider, Web
services offered, and bindings to the implementations .
Dynamically discovered Web services explicitly announce their arrival
and departure from the network.
16
Agreement Coordination
and
Enumeration
When multiple Web services complete a joint unit of work or
operate under a common behavior, there must be common
agreement on what protocols to use. This minimum amount of
coordination among Web services is unavoidable.
The specifications that define this functionality are
WS-ReliableMessaging, Reliable Messaging WS-Coordination, WS-
AtomicTransaction and WS-BusinessActivity.
Enumeration, in particular, is achieved though establishing
a session between the data source and the requestor.
Successive messages within the session transport the
collection of elements being retrieved.
They are based on WS-Enumeration, WS-Transfer, and WS-Eventing.
17
Security Challenges
Previously Security professionals tend to focus narrowly on
protecting assets
Modern security systems that intelligently manage and store user
information and cross-reference it with enterprise access rules
Presently Security professionals help to rapidly launch new
business activities while protecting assets
To maximize the reach of Web services, end-to-end security must
be provided when intermediaries are not trusted by the
communicating endpoints.
Even though the security requirements for Web services are
complex, no new security mechanisms were invented to satisfy
the needs of SOAP-based messaging
18
High Availability Web Services Using Cluster
Administrators of large Web sites are faced with managing the
growth in a 24x7 environment.
Networking strategies and services, and Server clustering
IP traffic destined for the virtual server is assigned to the server in
the cluster that is best suited for that transaction
Clustering of servers provides the following benefits :
Rapid response to unexpected growth
Balanced multiple work-load
Continuous application availability
Investment protection
19
Future Vision and Challenges
Technology vendors plan to develop, market, and lend online
Web services to fulfill virtually any business function.
Companies will be able to simply search a public directory of
applications and download those that fit their needs.
Right now we have only tools and standards which are still not
matured, but it’s needless to say that its time to learn and
practice some web services development
Challenges:
How will vendors provide end-to-end security?
Who is accountable when vendors fail to deliver promised services?
How will vendors guarantee availability and reliability?
How will vendors handle pricing?
20
Thank
You
21
