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February 1996
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Sunsoft'S Object Lesson
/ Comparing Spring
Spring is unique in many ways, but it's probably most like Mach, the microkernel-based operating system developed at Carnegie Mellon University. There are two main differences. First, Mach's microkernel contains a few more functions than Spring's: process management, virtual memory, interprocess communication, and device drivers. Second, Mach uses ports to communicate between machines. Suppose y
ou wanted a remote database. You would use a port, prepare a message for it, send it to the port, and the other end then figures out what to do. In Spring, the other end would have an IDL interface.
The other OS that comes to mind when you say "distributed" is AT&T's Plan 9. But
Plan 9 isn't object-oriented. Plan 9's main goal was to extend Unix's concept that "everything is a file." So, in Plan 9, applications talk to everything as though it were a file -- usually using a serial stream (e.g., a pipe or a byte stream).
In Spring, everything is an object, and you talk to every object as its IDL interface describes. In other words, in Spring, you could have an object that represents a person. Consequently, there would be an operation to find out a person's name. In Plan 9, an application would read from a data stream until it found a particular delimiter that the application knew was the start of the name, then read until it found the delimiter that meant the end of the name.
Matthew Wilson more...
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Comparing Spring
