AIS SERVER LITEA useful tool for the input/output of AIS messages. The LITE version is free for non-commercial use.
As an example, I'm currently using it to:
1. Read a TCP AIS input stream from my sp2trax program, receiving ships from ShipPlotter.
2. Read a TCP AIS input stream from another AIS server.
3. Output both of these as a single AIS output stream to COM1 for ShipTrax to read.
4. Output both of these as a single AIS output stream on a TCP port so that ShipPlotter on my other PC can read the same stream of AIS messages.
It can handle I/O on Serial, TCP, UDP, and SOAP.
I have no connection with SiiTech Inc, I'm just an end-user.
http://www.siitech.com/prod_as.htm