Weupnp is a lightweight Java library, released under the LGPL licence, designed to implement the UPnP protocol to handle port mappings on Gateway Devices.
Weupnp is used by the BitLet applet to open ports for incoming connections and to build an interactive console for the administration of port mappings on UPnP devices. Since version 1.6, the UPnP PortMapper can use weupnp to communicate with Gateway Devices.
The implementation of weupnp was inspired by miniupnp, a C UPnP library by Thomas Bernard.
If you wish to contribute, feel free to drop a line to the daniele.castagna and ale.bahgat (both at gmail.com).