Description of the WireCloud mashup engine, and its integration with other FIWARE Generic Enablers. It defines basic components such as widget, operator, and mashup, and goes on with advanced fuctionality of WireCloud such as Wiring, HTTP proxy, preferences, and the APIs to other FIWARE GenericEnablers. Finally, it contains a basic workshop on the usage of WireCloud. It exposes a chat application split into a widget and an operator.