In the heart of a modern general-purpose operating
system (OS) like Unix, there is usually a file system managing all long-term
resources. In a sense, modern general-purpose operating systems are built on
the file system. Different from most existing operating systems, Rambler does
not rely on the file system. Instead, Rambler is built on persistent objects,
resident in object containers. These object containers play a role of
"Object File System", a concept introduced by Cairo, the novel OS of Microsoft
Corporation. In an object container, there are many objects that live after the
program end, like the way files survive after the program ends. That is, these
objects are persistent. If an operating system can support such a kind of
objects, it can be called a persistent operating system. Rambler is a persistent operating system, built on a new
persistence model named Persistence By Location (PBL).
The following sections review the background of persistence systems, including the requirements, existing persistence models and concepts. Section 4 compares two trends of persistence systems. Section 5 gives a brief survey of current implementations of persistent systems. Section 6 introduces the concept of PBL.
1.
Persistent Object,
Persistent Model, and Persistent Programming Language
4.
Programming-oriented
persistence vs. database-oriented persistence