A Review of Internet Technology Part 5: Services

Web Services is a general term that comprises the modes in which devices or programs on the internet interact and communicate with each other.  There does not necessarily need to be any user interaction for web services to communicate with each other unless you are referring to SaaS (Software as a Service).  In that case web applications such as Gmail, Google Docs, Zoho, Ymail and even Facebook could be considered a web service.

There are two areas of web service - the original SOAP model that uses XML to set strict parameters of dialog between devices and the new RESTful model that is similar to a Web API.

Web services are the foundation for SOA (Service Oriented Architecture).  SOA is "a flexible set of design principles used during the phases of systems development and integration".  Basically meaning that software operates as a series of services rather than a massive program that attempts to do everything itself. This opens services up for modularity where additional functions can be plugged into the service without affecting other modules. The image below illustrates the modularity of a web service and how many components interact through the service. An example of a web service that everyone is common with is anti-virus.  In an office setting is is installed on each computer/server and the anti-virus is constantly monitoring the computers and network traffic suspicious activity.  In addition to constant monitoring it frequently checks with remote servers for new downloads to stay up to date.  If anything suspicious or harmful is found the anti-virus then alerts the user and can also send a ticket to tech support.  Anti-virus would be considered a RESTful service.  It checks for new updates on a set schedule and only performs system scans at a certain timeframe while.  Many anti-virus systems are modular allowing additional plugins to be installed for things like anti-spyware or email monitoring for specific clients like Outlook.