If you are thinking about getting a XML socket server for Flash you should seriously consider this new kid on the block: Oregano is a multiuser server for Flash clients written in Java. It is using JDBC to connect to any available database which it uses i.E. for user and group management. One specialty is the extensive API which allows you to send and receive complete AS-objects without prior parsing, similar to the AMF format. The whole server is very well documented and you can see it in action on the online community Zimmer Frei. If you are not convinced yet here is something that will: Oregano is Open Source and completely free.