frank@mnetor.UUCP (Frank Kolnick) (03/27/90)
In article <1555@wacsvax.OZ) kim@wacsvax.OZ (Kim Shearer) writes: )bdb@becker.UUCP (Bruce Becker) writes: ) )> More or less. All resources can be allocated )> to a job, including cpu, memory, files, disk )> drives, modems, etc. The difference is that )> you can tell (until the new version this )> year perhaps) where the resource lives, but )> you treat it locally (except for diskette )> drives - inserting a diskette halfway across )> a continent is a bit inconvenient 8^). One can )> get an executable from one machine, execute )> it on another, and have the screen/kybd i/o )> sent to your own machine - all simple to do, )> built in to the system. The name space isn't ) ) Umm, you can rcp files between machines on any unix network, and is ) there not also a remote execute command ? The point is that the OS ) should do this sort of thing IN A TRANSPERENT MANNER, ie without ) the user ever knowing about it, to be truely distributed. I think ) this is what Andy Tannenbaun is talking about, I do not know if this ) is what you meant, I may have misinterprited what you wrote. In fact, QNX lies somewhere between the two. (Perhaps it's semi-transparent.) You can access files without necessarily knowing where they are, i.e., the system can search across nodes for them. However, this isn't the same as saying that all files reside on the same 'virtual volume'. The same is true of other resources, like tasks and modems. The o/s does not treat resources as a system-wide pool, though. It is up to the applications to supply this extra layer of insulation. On the other hand, QNX is more than a network of loosely connected nodes, due primarily to its message- based orientation. This generally means that all tasks can communicate with each other regardless of their locations, without being aware of the separation. They do have to register their names and follow a few other rules, thereby violating the concept of transparency. Personally, I think this qualifies QNX as distributed. I would say that Amoeba is a step beyond, but can't think of a formal term to describe it. (Btw, no one mentioned Tandem. Last time I looked -- several years ago -- they were on the verge of transparent network access and were talking about automatic load-sharing. Did that actually happen?) -- Frank Kolnick, Basis Computer Systems Inc. UUCP: {allegra, linus}!utzoo!mnetor!frank