The OnCommand event occurs after the client has sent a
command to the server, but before the command has been processed. This
event occurs for all commands issued by the client, including invalid
or disabled commands. If the application wishes to handle the command
itself, it must perform any processing and then call the
SendResponse method to send the success or error code to the
client. If the SendResponse method is not called, then the
server will perform its default processing for the command.
After the command has been processed, the OnResult event
handler will be invoked.