The input method server comprises three related programs (htt_props, htt, htt_server) processes running together. One process controls the input method server properties, one process controls the population of the input method server (i.e., a watch dog process), and the third handles input methods of clients.
Usually, you don't need to know the details of these three processes. When htt is started, htt_props and htt_server are started automatically.