| [[introduction]] |
| == Introduction |
| |
| This Guide covers Virgo Snaps and assumes you are already |
| familiar with OSGi and Eclipse Virgo. See link:#further-reading[here]. |
| |
| [[introduction-concepts]] |
| === Concepts |
| |
| Using Virgo Snaps, or VS for short, you |
| can construct a web application from multiple OSGi bundles, each of |
| which serves up content for a distinct sub-portion of your application's |
| URL space. VS applications are arranged in a |
| parent/child structure, with each application having at most one |
| top-level parent, and zero or more children/grand children and so on. |
| Parents are referred to as the hosts, children as snaps. |
| |
| image::images/snapsAndHosts.png[] |
| |
| Here you see that any `HTTP` requests for '/app' will be dealt with by |
| the host bundle while '/app/orders' and '/app/billing' will be dealt |
| with by their respective snaps bundles. Each host/snap can use |
| completely different web technologies to deal with the requests, |
| Virgo Snaps places no restrictions on your choices. The |
| developer decides how to split the application up and how closely to |
| couple the host and various snaps. VS has been |
| designed to be as un-invasive as possible while still making it easy to |
| share information between the host and its snaps. |
| |
| [[introduction-prereqs]] |
| === Prerequisites |
| |
| VS requires Virgo Server for Apache Tomcat and Java SE 6 |
| or later to be installed. Java is available from http://www.java.com/ |
| and elsewhere. Virgo Server for Apache Tomcat is available from |
| http://www.eclipse.org/virgo/download/[here]. |
