Internals
Read this if you want to investigate in socket.io-java-client.
SocketIO is the API frontend. You can use this to connect to multiple hosts. If an IOConnection object exists for a certian host, it will be reused as the socket.io specs state.
This class is used to hold a connection to a socket.io server. It handles calling callback functions of the corresponding SocketIO and reconnecting if the connection is shut down ungracefully.
This interface describes a connection to a host. The implementation can be fairly minimal, as IOConnection does most of the work for you. Reconnecting, errorhandling, etc... is handled by IOConnection.
See also: How to implement a transport