| 摘要 |
In a distributed object system, a stable object iterator provides a list of all persistent objects within a collection of objects. A plurality of iterators are supported in another aspect of the invention. An iterator associates a label with each persistent object in a collection of stable objects. The label indicates whether the associated object was added to or deleted from the collection before or after the inception of an iterator. Multiple persistent iterators are supported by providing an indication of which iterators each persistent object is, or is not, "visible" to. Should an element of the persiste nt object collection be created after one or more iterators is created, that elemen t is "invisible" to those iterators. Objects that exist when one or more iterators are created remain "visible" to those iterators, even if the object is deleted from the collection while those iterators still exist. The system maintains an indication of all extent iterators and of maximum and minimum iterator identifiers which respectively correspond to the most recently created and least recently created iterators.
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