You can use the Reader RP Proxy, if you want to write your own Java code and you are looking for a
easy-to-use library that abstracts from the message and transport bindings.
If you are just looking for a graphical user interface to generate some Reader Protocol commands, you might want to consider our ReaderTestClient.
The Fosstrak project has an active developer community with significant RFID middleware experience and insights into the RFID/EPC standardisation process. There is a strong focus on implementing the specifications developed by EPCglobal and its members and providing useful tools for these implementations. Remember though that this is beta software currently. Don't expect the support you would be getting from a software vendor offering RFID middleware solutions!