Aleph was an early step on the road to the creation of the first practical microkernel operating system, Mach.
Aleph used inter-process communications to move data between programs and the kernel, so applications could transparently access resources on any machine on the local area network (which at the time was a 3-Mbit/s experimental Xerox Ethernet).
The project eventually petered out after several years due to rapid changes in the computer hardware market, but the ideas led to the creation of Accent at Carnegie Mellon University, leading in turn to Mach.
Processes could open several ports and then "read" them, automatically blocking and allowing other programs to run until data arrived.
Another problem, realized only in retrospect, was that the use of global ID's allowed malicious software to "guess" at ports and thereby gain access to resources they should not have had.