Wt mean by web services ?




Anbudan
Prasath.K

The W3C defines a Web service (many sources also capitalize the second word, as in Web Services) as a software system designed to support interoperable Machine to Machine interaction over a network. Web services are frequently just Web APIs that can be accessed over a network, such as the Internet, and executed on a remote system hosting the requested services.

The W3C Web service definition encompasses many different systems, but in common usage the term refers to clients and servers that communicate using XML messages that follow the SOAP standard. Common in both the field and the terminology is the assumption that there is also a machine readable description of the operations supported by the server, a description in the Web Services Description Language (WSDL). The latter is not a requirement of a SOAP endpoint, but it is a prerequisite for automated client-side code generation in the mainstream Java and .NET SOAP frameworks. Some industry organizations, such as the WS-I, mandate both SOAP and WSDL in their definition of a Web service.

thanks

__________________
Karpagarajan. R
Necessity is the mother of invention

hi,
ur reply satisfied for me,i have one more doubt,i have known in my level,web services are in .Net.Any other technology except from .Net,can use the web services.


Thanks,
Prasath.K

Hi,

A Web Service is an external interface provided by a Web site that can be called from other Web sites. This information could be read from a Web page and displayed, or read from a stand-alone application on a customer's desktop computer.

Web services provide the ability to share data with a large variety of clients. non-proprietary way.
No specific requirements to develop solutions that use that service.

Components

A Web service consists of three primary components:

1. The SOAP "listener"
2. The business logic object
3. The discovery of Web service file (DISCO file)

SOAP Object
Web services and clients use the Simple Object Access Protocol (SOAP) For communicating with one another.

SOAP essentially allows a client to make a request to a registered object on a server via standard Internet protocols, such as HTTP.
Not needed to configure special ports to allow access Web service.

The service can be implemented to run right over the same HTTP port like a Web server runs.

Business logic object

This object can be a traditional COM object or a .NET component.

DISCO File

DISCO is a Microsoft® technology for publishing and discovering Web Services. Universal Description, Discovery, and Integration (UDDI) is an industry-wide initiative that defines a SOAP-based protocol for updating and querying Web Service information repositories

Publishing and Discovering Web Services with DISCO and UDDI (Disco.exe)
Web Services Discovery Tool (Disco.exe)

A Web Service in .Net consists of a .ASMX page that either contains a class that provides the Web Service functionality or references a specific external class that handles the logic in an external class file.



.Net Web Services that run over HTTP can be called in 3 different ways:

• HTTP GET Operation
  Pass parameters to a Web Service by calling the ASMX page with query string parameters for the method to call and the values of simple parameters to pass.
  Example: WebDemo.asmx/MethodName?Parm1=value
  
• HTTP POST Operation
  Works the same as GET Operation except that the parameters are passed as standard URL encoded form variables.
  Example: WebDemo.asmx/MethodName
  
• SOAP
  This is the proper way to call a Web Service in .Net and it’s also the way that .Net uses internally to call Web Services.

The GET and POST operations are useful if you need to call a Web Service quickly and no SOAP client is readily available.

-R.Gopi