WebService ::: Part2:-introduction

What is Web Service?
Web Services are applications that can be published, located, and invoked across the Internet. A Web service is a unit of managed code that can be remotely invoked using HTTP, that is, it can be activated using HTTP requests.
The World Wide Web Consortium (W3C) has defined the web services. According to W3C, “Web Services are the message-based design frequently found on the Web and in enterprise software. The Web of Services is based on technologies such as HTTP, XML, SOAP, WSDL, SPARQL, and others.”

Web Services Architecture

• Service Processes: This part of the architecture generally involves more than one Web service. For example, discovery belongs in this part of the architecture, since it allows us to locate one particular service from among a collection of Web services.
• Service Description: One of the most interesting features of Web Services is that they are self-describing. This means that, once you've located a Web Service, you can ask it to 'describe itself' and tell you what operations it supports and how to invoke it. This is handled by the Web Services Description Language (WSDL).
• Service Invocation: Invoking a Web Service involves passing messages between the client and the server. SOAP (Simple Object Access Protocol) specifies how we should format requests to the server, and how the server should format its responses.
• Transport: Finally, all these messages must be transmitted somehow between the server and the client. The protocol of choice for this part of the architecture is HTTP (Hyper Text Transfer Protocol), the same protocol used to access conventional web pages on the Internet.
• Universal Description, Discovery, and Integration (UDDI) is a protocol for describing available Web services components. This standard allows businesses to register with an Internet directory that will help them advertise their services, so companies can find one another and conduct transactions over the Web. This registration and lookup task is done using XML and HTTP(S)-based mechanisms.

Why Web Services?

Here are the benefits of using Web Services:

1. Exposing the function on to network: A Web service is a unit of managed code that can be remotely invoked using HTTP that is, it can be activated using HTTP requests. So, Web Services allows you to expose the functionality of your existing code over the network. Once it is exposed on the network, other application can use the functionality of your program.
2. Connecting Different Applications: Web Services allows different applications to talk to each other and share data and services among themselves. So, Web services is used to make the application platform and technology independent.
3. Standardized Protocol: Web Services uses standardized industry standard protocol for the communication. All the four layers (Service Transport, XML Messaging, Service Description and Service Discovery layers) uses the well defined protocol in the Web Services protocol stack. This standardization of protocol stack gives the business many advantages like wide range of choices, reduction in the cost due to competition and increase in the quality.
4. Low Cost of communication: Web Services uses SOAP over HTTP protocol for the communication, so you can use your existing low cost internet for implementing Web Services. This solution is much less costly compared to proprietary solutions like EDI/B2B.
5. Support for Other communication means: Beside SOAP over HTTP, Web Services can also be implemented on other reliable transport mechanisms. So, it gives flexibility use the communication means of your requirement and choice. For example Web Services can also be implemented using ftp protocol (Web services over FTP).
6. Loosely Coupled Applications: Web Services are self-describing software modules which encapsulates discrete functionality. Web Services are accessible via standard Internet communication protocols like XML and SOAP. These Web Services can be developed in any technologies (like c++, Java, .NET, PHP, Perl etc.) and any application or Web Services can access these services. So, the Web Services are loosely coupled application and can be used by applications developed in any technologies.
7. Web Services Sharing: These days due to complexness of the business, organizations are using different technologies for distributing computing. Web Services supports all these technologies, thus helping the business to use existing investments in other technologies.
8. Web Services are Self Describing: Web Services are self describing applications, which reduces the software development time. This helps the other business partners to quickly develop application and start doing business. This helps business to save time and money by cutting development time.
9. Automatic Discovery: Web Services automatic discovery mechanism helps the business to easy find the Service Providers. This also helps your customer to find your services easily. With the help of Web Services your business can also increase revenue by exposing their own Web Services available to others.
10. Business Opportunity: Web Services has opened the door to new business opportunities by making it easy to connect with partners.