Hightide is an optimized, versioned distribution of the Jetty open source web container. It comes pre-integrated with a number of services usually only found in J2EE application servers, or which you would otherwise have to craft together yourself: JNDI, an XA transaction service, a JMS message fabric, and a JDBC accessible database. Thanks to Jetty's light weight, pluggable architecture, Hightide allows you to easily choose which of these services you want to use, or even replace them with others.
Additionally, Hightide is pre-configured with state-of-the-art Ajax communication libraries such as the Bayeux protocol (also known as cometd). Deploying your applications on Hightide means that it will scale smoothly thanks to a combination of Jetty's smart IO layer and continuations mechanism.