Service oriented architecture is an architectural model for developing distributed systems across a network or the Internet. The main goal of this model is to create a collection of sub-systems to function as one unified system. This approach allows applications to work within the context of a client server relationship much like a web browser would interact with a web server. In this relationship a client application can request an action to be performed on a server application and are returned to the requesting client. It is important to note that primary implementation of service oriented architecture is through the use of web services.

Web services are exposed components of a remote application over a network. Typically web services communicate over the HTTP and HTTPS protocols which are also the standard protocol for accessing web pages on the Internet.  These exposed components are self-contained and are self-describing.  Due to web services independence, they can be called by any application as long as it can be accessed via the network.  Web services allow for a lot of flexibility when connecting two distinct systems because the service works independently from the client. In this case a web services built with Java in a UNIX environment not will have problems handling request from a C# application in a windows environment. This is because these systems are communicating over an open protocol allowed by both environments. Additionally web services can be found by using UDDI.

References:

Colan, M. (2004). Service-Oriented Architecture expands the vision of web services, Part 1. Retrieved on August 21, 2011 from http://www.ibm.com/developerworks/library/ws-soaintro/index.html

W3Schools.com. (2011). Web Services Introduction - What is Web Services. Retrieved on August 21, 2011 from http://www.w3schools.com/webservices/ws_intro.asp