<p>I am very new to creating webservers - and I have had several goes at trying to understand them and write a quick webserver, but it's never quite 'clicked'.  At the moment I am under the impression that REST would be most suitable for my purposes (I will explain later).</p>

<p>Can anyone either show me a basic code example in Java (using Tomcat Apache) or a tutorial resource to show how a webserver:</p>

<ul>
<li>Can be used for security - i.e. pass in some kind of value to identify the client - from their the webserver will either deny or grant access to the client dependant on some criteria - maybe a lookup list.</li>
<li>Once the client is successfully accepted they will be allowed to pass in some more values to the webserver that will be used to write a row in a database table.</li>
</ul>

<p>Many thanks.</p>

<p>PS - I would have thought there might have been soemthing that comes with Eclipse Ganymede? If someone can confirm?</p>

The best way to write restful resources in Java is via the JAX-RS standard. So I'd recommend you download
Jersey which is the JAX-RS reference implementation
and check out its examples; its got lots of them. Take an example for a spin then try hacking it to do what you like.
BTW JAX-RS can be run inside any Servlet engine - you just build a WAR and deploy it (there are examples in the Jersery samples) - though Jersey also comes with a small lightweight web server you can use too which is a little easier to use - again there are examples in the distro of this.