I want to use the balanced tree mechanism to implement an updatable set of one key records. I want to efficiently access these records by key and pass over them in sorted order. The code is too complex and new to go into the kernel and most applications don’t need it. A particular instance of such a record set is usually shared between several applications, each with distinct authority to access the set. Clearly the balanced tree code and its abstracted data structures cannot go in the address space of any particular application address space.

Unix does not support such function. IBM mainframe systems provide a place for each function but the special hardware features they introduced for this function are not completely documented and it seems that only IBM can add such middleware. Aegis seems to be like early IBM mainframe systems with no place for such code. QNX provides places for such middleware but the procnto facility does not seem suited to providing access to just those applications that need access to a particular instance.

This is not the only middleware function required.