Code:
option userspace yes - (default: no) If specified, this file describes a userspace (ie, non-realtime) component, rather than a regular (ie, realtime) one. A userspace component may not have functions defined by the function directive. Instead, after all the instances are constructed, the C function void user_mainloop(void); is called. When this function returns, the component exits. Typically, user_mainloop() will use FOR_ALL_INSTS() to perform the update action for each instance, then sleep for a short time. Another common action in user_mainloop() may be to call the event handler loop of a GUI toolkit.
From that I guess some form of loop is needed. (my basic understanding)
