Web service is a piece of software which is integrated with the Web-based Application and make themselves to available over internet. To encode all communication XML is used in web service which is like a client invoke a request sending an XML message then waits for his request in XML response. Communication with services done in XML, Web services are not tied to any single language or platform, different language can talk to different one like java to Perl and same with the Platform windows application can talk to Unix one. This services allow communication behind the firewall so that organization can communicate without intimate knowledge. Services built on top of the open standards which is interoperable like TCP/IP, HTTP, Java, HTML and XML. In other words we can say a service is a collection of open protocol whose primary purpose to exchange data between application or systems.
Web-based application using some of the open standards and basic web service platform are a combination of XML and HTTP. So we are going to discuss some of the components used by web services.
There are multiple factors that need to take care while choosing a web service which are between the two SOAP and REST.
RESTful web services are completely stateless and user can test them by restarting the server and check the interaction are able to survive or not. The service provide by Restful web service is a good cache infrastructure over HTTP by using GET method which is used by most of the servers. This can also improve performance if the data return by web service not altered. As there is no standard rules to pass the content between service provider and service consumer so they need to have the common understanding. This web service is useful for restricted-profile device such as mobile for which overhead of additional parameters are less. These services are easy to integrate with the existing applications or websites. This is ease for developers not to rewrite from scratch and add existing functionality. Implementation of REST is simple as compared to SOAP.
As we know all the real world applications are not simple, they support complex operations, and to design complex operation we required conversational state and contextual information to be maintained. So by using SOAP developers no need to worry about writing plumbing code in application layer by themselves because SOAP require less plumbing code as compared to REST. These web services are useful to handle asynchronous processing and request of data. This support several protocols and technologies which are interoperable like UDDI, WSDL, XML WS-addressing. WSDL is a common set of rules to define the messages, binding, operations and the location of the services.
In generally if we talk about end-point is the finishing line. So in terms of web services end-point is the connection point where HTML files or active pages are exposed. In other words we can say end point is a URL that are accessed by client application when the web service is either complete or host on web. It provide a reference and specification that is used to define a group of message addressing properties and give end-to-end characteristics end-point can be a point-of-sale terminal. Lets take an example of web services end-point a SBI bank has so many ATMs services in a city or in different cities so all the ATMs are the endpoints which the unique address or we can say a web services can have multiple end-points with the unique address that is known as port.