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| | The Vat |
 | | Rounded rectangles are Vats, circles and normal rectangles are objects, thin arrows are references (i.e., capabilities), and the thick stubby arrow is a message. |
 | | Vat boundaries show up in the semantics in a number of other places, in order to reflect the inescapable issues of distributed systems: concurrency, asynchrony, several kinds of partial failure, resource control, and decentralized administration. |
 | | In this sense, a Vat is vaguely like a traditional OS process -- it bundles together a single thread of control and an address space of synchronously accessible data, and so avoids the need for bug-prone fine-grained locking on this data. |
| www.erights.org /elib/concurrency/vat.html (583 words) |
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