Implementations of the {@link com.primix.tapestry.IEngine} interface, including the standard implementation: {@link com.primix.tapestry.engine.SimpleEngine}. Also located here are default implementations of all the basic support objects, including {@link com.primix.tapestry.engine.RequestCycle} (which implements {@link com.primix.tapestry.IRequestCycle}). @author Howard Ship hship@primix.com