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High 'Standards'

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DQI Bureau
New Update

Web Services have played a major role in enabling the new generation of

Internet-based applications. There are countless examples of applications that

have been made possible by Web Services-automated business transactions and

direct (non-browser) desktop as well as handheld device access to reservations,

stock trading, and order-tracking systems. Web Services allow applications at

different network locations to be integrated to functions as if they were part

of a single, large software system.

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Web Services are becoming very important, but without standards support to

ensure interoperability, they're worthless. Web Services platforms must

conform to industry standards such as the Web Services Interoperability

Organization's (WS-I) Basic Profile 1.0 (a set of rules specifying how to

implement key Web services specifications). WS-I is an open industry

organization chartered to promote Web services interoperability across

platforms, operating systems and programming languages.

Standardization is important so that customers won't be locked into a

particular vendor's implementation. So, several key standards have emerged.

Some of the prominent ones being XML (Extensible Markup Language), WSDL (Web

Services Definition Language), SOAP (Simple Object Access Protocol), and UDDI

(Universal Description, Discovery and Integration). Among these, XML has emerged

as a flexible way to create standard information formats and share both the

format and the data on the World Wide Web. The portability and extensibility of

both XML and Java technologies make them a natural match for the creation of

applications-where different classes of clients consume and generate

information that is exchanged between different servers running on multiple

system platforms. SOAP is the standard messaging protocol used by J2EE Web

Services, and is the de facto standard for Web Services. Its primary application

is Application-to-Application (A2A) communication. Specifically, it's used in

Business-to-Business (B2B) and Enterprise Application Integration (EAI), which

are two sides of the same coin: both focus on integrating software applications

and data sharing. UDDI creates a platform-independent, open framework for

describing services, discovering businesses, and integrating business services

using the Internet.

Web Services Description Language (WSDL) is the current proposed standard to

describe a Web Service, an Interface Definition Language (IDL) service based on

XML that defines the service interface and its implementation characteristics.

WSDL is referenced by UDDI entries and describes the SOAP messages that define a

particular Web service.

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How it Works...

Web Services expose their capabilities to client applications, not their implementations. This allows Web Services to be implemented in any language and on any platform and still be compatible with all client applications.



- Each Web Service is self-contained. It describes its own capabilities, publishes its own programmatic interface, and implements its own functionality that is available as a hosted service.


- The business logic of a Web Service runs on a remote machine that is accessible by other applications through a network. The client application simply invokes the functionality of a Web Service by sending it messages, receives return messages from the Web Service, and then uses the results within the application. There is no need to integrate the Web Service within the client application into a single monolithic block. This reduces development and testing times, maintenance costs, and overall errors.

What are Web Services

Web Services are pieces of application functionality or business processes that are available for use by other applications-either internally to the enterprise or externally with other companies and organizations. Any application can use a Web Service by simply addressing it using its URL, and invoking it across a network. The capabilities provided by a Web Service can fall into a variety of categories, including:

  • Functions, such as a routine for calculating the integral square root of a number

  • Data, such as fetching the quantity of a particular widget a vendor has in inventory, or the stock price of a company

  • Business processes, such as accepting an order for a widget, shipping the

    desired quantity of widgets, and sending an invoice



    Some of these capabilities are difficult or impractical to integrate within third-party applications. When these capabilities are exposed as Web Services, they can be loosely coupled together, thereby achieving the benefits of integration without incurring the difficulties thereof.

Web Services offer capabilities that can be used by client applications by invoking it across a network using its URL. The client application does not have to integrate the Web Services, but simply uses their capabilities as remote services

Web Services are also finding increased utilization due to technologies like

Grid Computing. These technologies are providing improved utilization of

existing heterogeneous resources while increasing productivity and collaboration

for valuable technical professionals. Increased levels of integration,

standardization, and higher levels of abstraction are finally allowing

management of services, rather than individual hardware, operating system, and

application platforms.

Again, one of the important parameters that CIOs must look for is

interoperability. Your Web Services platform must enable you to quickly design,

develop, test and deploy web services and clients that fully interoperate with

other Web Services and clients running on any platform. Today, complete

interoperability is possible due to a standardized XML-based data stream.

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Open, interoperable systems, could one day enable software to run on any

operating system. After all, Web Service emerged as the solution for providing a

standard way to retrieve data without proprietary software and hardware. A Web

Service cornerstone is its ability to transfer data from the provider to the

consumer, or someone who requests, using the ubiquitous HTTP protocol for an XML

format. Formatting the data in XML greatly facilitates raw data's conversion

into a renderable format. Extensible Stylesheet Language Transformations (XSLT)

perform the transformation rather easily.

Today, support for Web Service is considered to be of utmost importance.

Finally, a standards-based web services model, if used effectively, has the

capacity to deliver extra ordinary benefits to any enterprise-big or small.

With contribution from editorial advisor Anil Valluri, director,

Client Solutions Organization, Sun Microsystems India

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Technologies of Web Services

The technologies that form the foundations of Web Services are SOAP, WSDL and

UDDI.

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SOAP Simple Object Access Protocol is an XML-based mechanism for exchanging

information between applications within a distributed environment. This

information exchange mechanism can be used to send messages between

applications, and more specifically, can be used to implement remote procedure

calls (RPCs)

WSDL Web Services Description Language is an XML-based language for

describing Web Services. Through a WSDL description, a client application can

determine the location of the remote Web Service, the functions it implements,

as well as how to access and use each function. After passing a WSDL

description, a client application can appropriately format a SOAP request and

dispatch it to the location of the Web Service

UDDI Universal Description, Discovery and Integration is a specification for

a registry of information for Web Services. UDDI defines a means to publish, and

more importantly, discover (or search for) information, including WSDL files,

about Web Services.

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