There are many approaches to realizing SOA, but the most popular and practical one is using web services.
What is a web service?
As mentioned in the beginning of this chapter, a web service is a software system designed to support interoperable machine-to-machine interaction over a network. A web service is typically hosted on a remote machine (provider) and called by a client application (consumer) over a network. After the provider of a web service publishes the service, the client can discover it and invoke it. The communications between a web service and a client application to be used can be done by sending XML messages. A web service is hosted within a web server and HTTP is used as the transport protocol between the server and ...