2. INTRODUCTION
“A Web Service is an application component
accessible over open protocols”.
Software Developers tries to develop software
component which can be called over local
networks or global networks
Accessed Over The Internet
Web Services are objects and methods that can be
invoked from any client over HTTP. 2
3. OVERVIEW
HTML pages (or the HTML output generated by
ASP.NET web forms) are meant to be read by the
end user, web services are used by other
applications.
They are pieces of business logic that can be
accessed over the Internet.
For example, e-commerce sites can use the web
service of a shipping and packaging company to
calculate the cost of a shipment.
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4. OVERVIEW
A news site can retrieve the news headlines and
articles produced by external news providers and
expose them on its own pages in real time.
A company can even provide the real-time value of
their stock options, reading it from a specialized
financial or investment site.
All of these scenarios are already taking place on
the Web, and major Internet companies such as
Amazon, Google, and eBay are providing their own
web service offerings to third-party developers.
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5. OVERVIEW
With web services, you can reuse someone else’s
business logic instead of replicating it yourself,
using just a few lines of code.
This technique is similar to what programmers
currently do with libraries of APIs, classes, and
components.
The main difference is that web services can be
located remotely on another server and managed
by another company.
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6. WHY WS?
Web Services were intended to solve three main
problems:
Interoperability
Firewall traversal
Complexity
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7. INTEROPERABILITY
Earlier distributed systems suffered from
interoperability issues because each vendor
implemented its own on-wire format for distributed
object messaging.
Development of DCOM apps strictly bound to
Windows Operating system.
Development of RMI bound to Java programming
language.
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8. FIREWALL
Collaboration across corporations was an issue
because distributed systems such as CORBA and
DCOM used non-standard ports.
Web Services use HTTP as a transport protocol
and most of the firewalls allow access though port
80 (HTTP), leading to easier and dynamic
collaboration.
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9. COMPLEXITY
Web Services is a developer-friendly service
system.
Most of the above-mentioned technologies such as
RMI, COM, and CORBA involve a whole learning
curve.
New technologies and languages have to be learnt
to implement these services.
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10. BENEFITS
Web services represent the next logical step in the
evolution of component-based distributed
technologies. Some key advantages include the
following:
Web services are simple: That simplicity means
they can be easily supported on a wide range of
platforms.
Web services are loosely coupled: The web
service may extend its interface and add new
methods without affecting the clients as long as it
still provides the old methods and parameters. 10
11. BENEFITS
Web services are stateless: A client makes a request
to a web service, the web service returns the result, and
the connection is closed.
There is no permanent connection. This makes it easy
to scale up and out to many clients and use a server
farm to serve the web services. The underlying HTTP
used by web services is also stateless.
Web services are firewall-friendly: Firewalls can
cause a challenge for distributed object technologies.
The only thing that almost always gets through firewalls
is HTTP traffic on ports 80 and 443. Because web
services use HTTP, they can pass through firewalls
without explicit configuration. 11
13. FINDING WEB SERVICES
In a simple application URL of the web service
have to place it in a configuration file. No other
steps are required.
In other situations, search for the web service.
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14. DISCO
Stands for Discovery Of Services
creates a file that groups a list of related web
services.
A company can publish a DISCO file on its server
that contains links to all the web services it
provides.
Clients simply need to request and find all these
web services
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15. UDDI
UDDI - Universal Description, Discovery, and
Integration
Centralized Directory for web services
UDDI registries
Web Services Interface
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16. WSDL
WSDL - Web Service Description Language
How to access a web service.
Contain what methods are available, what
parameters each method uses, and what the data
type of each parameter is.
XML-based language.
Describes Request and Response message.
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17. SOAP
SOAP - The Simple Object Access Protocol.
Industry-standard message format that enables
message-based communication.
Proxy class
Implements a message format based on XML to
exchange function requests and responses(HTTP
POST).
Using XML as the basis for SOAP understandable
and transportable using any system and any
Transport Protocol(HTTP).
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28. LIMITATION
We can not add our implementation to web
services
If any web service provider stop his web service
than we can not get output that we want.
We can not get any coding about web services
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29. CONCLUSION
Constructing application-to-application Web
services are simple, in principle.
By using web service we can get methods which
we do not need to implement and also can
provide methods to users on local server without
showing our implementation code to them.
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