Web services allow different organizations or applications from multiple sources to communicate without the need to share sensitive data or IT infrastructure. All information is instead shared through a programmatic interface across a network. This interface can then be added to a GUI, like a web page, to deliver specific functionality to users. Due to this, web services are not specific to one programming language or operating system and do not require the use of browsers or HTML.
The term "Web service" describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet Protocol backbone. XML is the data format used to contain the data and provide metadata around it, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI lists what services are available.
Web services architecture: the service provider sends a WSDL file to UDDI. The service requester contacts UDDI to find out who is the provider for the data it needs, and then it contacts the service provider using the SOAP protocol. The service provider validates the service request and sends structured data in an XML file, using the SOAP protocol. This XML file would be validated again by the service requester using an XSD file.
Registration of a domain does not automatically imply the provision of DNS services for the registered domain. Most registrars do offer DNS hosting as an optional free service for domains registered through them. If DNS services are not offered, or the end-user opts out, the end-user is responsible for procuring or self-hosting DNS services. Without DNS services for the domain, the registration is essentially useless for Internet services, although this situation is often encountered with domain parking and cybersquatting.
Web services use something known as SOAP (Simple Object Access Protocol) for sending the XML data between applications. The data is sent over normal HTTP. The data which is sent from the web service to the application is called a SOAP message. The SOAP message is nothing but an XML document. Since the document is written in XML, the client application calling the web service can be written in any programming language.