What is Web Service? Explain Web Service.

What is Web Service?

Web Service is an application that is designed to interact directly with other applications over the internet. In simple sense, Web Services are means for interacting with objects over the Internet. The Web service consumers are able to invoke method calls on remote objects by using SOAP and HTTP (HTTP-POST, HTTP-GET) over the Web.

Web Service is:=

• Language Independent
• Protocol Independent
• Platform Independent
• It assumes stateless service architecture.

Web Service Communication
Web Services communicate by using standard web protocols and data formats, such as

• HTTP
• XML
• SOAP 
• WSDL 
• UDDI

Standard Web Protocols:

Ø  HTTP (Hyper Text Transfer Protocol):

HTTP is the World Wide Web standard for communication over the Internet. HTTP is standardized by the World Wide Web Consortium (W3C).

Ø  XML (Extensible Markup Language):

XML  is a well known standard for storing, carrying, and exchanging data. XML is standardized by the W3C. 

Ø  SOAP (Simple Object Access Protocol):

SOAP is a remote function calls that invokes method and execute them on Remote machine and translate the object communication into XML format. In short, SOAP are way by which method calls are translate into XML format and sent via HTTP.

Ø  WSDL(Web Services Description Language):

 

WSDL (Web Services Description Language) is an XML-based language used to define web services and to describe how to access them.  WSDL is a standard by which a web service can tell clients what messages it accepts and which results it will return. WSDL contains every detail regarding using web service and Method and Properties provided by web service and URLs from which those methods can be accessed and Data Types used. WSDL is a suggestion by Ariba, IBM and Microsoft for describing services for the W3C XML Activity on XML Protocols.

Ø  UDDI(Universal Description, Discovery and Integration):

Ø  UDDI provides a XML based standard mechanism for clients to dynamically find other web services.

Ø  UDDI is a directory service where businesses can register and search for web services.

Ø  UDDI is a public registry, where one can publish and inquire about web services.

Ø  UDDI is platform independent, open framework.

Ø  UDDI can communicate via SOAP, CORBA, Java RMI Protocol. UDDI uses WSDL to describe interfaces to web services.

 UDDI has two parts:

Ø  A registry of all a web service's metadata including a pointer to the WSDL description of a service

Ø  A set of WSDL port type definitions for manipulating and searching that registry 

Example of Web Service:

• Weather Reporting: You can use Weather Reporting web service to display weather information in your personal website.
• Stock Quote: You can display latest update of Share market with Stock Quote on your web site.
• News Headline: You can display latest news update by using News Headline Web Service in your website.

Advantages of Web Service:

Web Service messages are formatted as XML, a standard way for communication between two incompatible system. And this message is sent via HTTP, so that they can reach to any machine on the internet without being blocked by firewall.