Many organizations use multiple software systems for management.[citation needed] Different software systems often need to exchange data with each other, and a Web service is a method of communication that allows two software systems to exchange this data over the Internet. The software system that requests data is called a service requester, whereas the software system that would process the request and provide the data is called a service provider.
Now we discussed in the previous topic about WSDL and how it contains information on what the Web service actually does. But how can a client application locate a WSDL file to understand the various operations offered by a web service? So UDDI is the answer to this and provides a repository on which WSDL files can be hosted. So the client application will have complete access to the UDDI, which acts as a database containing all the WSDL files.
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.
You can find out if a domain name is available by searching at the top of this page. If the domain name you want is not available, try selecting a suggested alternative that appears or searching again. If you’re still stuck, our free guide, Bringing your business online: How to choose a domain name and more, provides some more in-depth information about domain names and helps guide you through the process.
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Now we discussed in the previous topic about WSDL and how it contains information on what the Web service actually does. But how can a client application locate a WSDL file to understand the various operations offered by a web service? So UDDI is the answer to this and provides a repository on which WSDL files can be hosted. So the client application will have complete access to the UDDI, which acts as a database containing all the WSDL files.
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. 

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In practice, a Web service commonly provides an object-oriented Web-based interface to a database server, utilized for example by another Web server, or by a mobile app, that provides a user interface to the end-user. Many organizations that provide data in formatted HTML pages will also provide that data on their server as XML or JSON, often through a Web service to allow syndication, for example, Wikipedia's Export. Another application offered to the end-user may be a mashup, where a Web server consumes several Web services at different machines and compiles the content into one user interface.
^ Compare: Oya 2008, "Under the current Web Services, […] stakeholder systems must follow the predefined rules for a particular business service including those about business protocols to send/receive messages and about system operation. […] More flexible mechanism is desired where freely built and autonomously running systems can exchange business messages without pre-agreed strict rules. We call it Autonomous Web Services (AWS) and proposed the framework called Dynamic Model Harmonization (DMH) with its algorithm, which dynamically adjusts different business process models between systems […]."[4]
Web services are used for a variety of applications, but the most common is for reusing code and connecting existing programs. The web service method can help developers segment applications into components that can be used and reused for various needs. For example, more than one program might need a conversion tool or a reporting function. This is possible due to web services’ universal communication protocols.
A web service is any piece of software that makes itself available over the internet and uses a standardized XML messaging system. XML is used to encode all communications to a web service. For example, a client invokes a web service by sending an XML message, then waits for a corresponding XML response. As all communication is in XML, web services are not tied to any one operating system or programming language—Java can talk with Perl; Windows applications can talk with Unix applications.

^ Mockapetris, P.V. (November 1987). "Domain names - concepts and facilities" (HTML). IETF Documents. IETF. doi:10.17487/RFC1034. Retrieved 24 July 2017. Relative names are either taken relative to a well known origin, or to a list of domains used as a search list. Relative names appear mostly at the user interface, where their interpretation varies from implementation to implementation, and in master files, where they are relative to a single origin domain name. The most common interpretation uses the root "." as either the single origin or as one of the members of the search list, so a multi-label relative name is often one where the trailing dot has been omitted to save typing.
A web service always hides the internal complexity of the service to its clients. For an example, an airliner which is selling tickets via a third party portal is only gathering end user info via a web service and in return it is providing ticket. The portal which is selling ticket doesn't have to bother about the internal complexity of the airlines ticket reservation systems.
"All the standard Web Services works using following components:" ... the problem with this answer is that it suggests that web services do or must operate within the SOAP/WSDL mechanism. This is inaccurate. Representational State Transfer (REST) is another very popular paradigm for implementing web services. Some major websites have deprecated their SOAP services in favor of REST web services. – scottb Jul 7 '15 at 15:50 
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