Persistent Processes and Distribution in Timor.

Abstract

The paper explains the concept of persistent processes and threads in Timor, showing how it is based on the in-process (procedure oriented) model of process execution. In their Timor form processes and threads can persist even when a user is logged out. They can also invoke remote persistent objects with the same semantics as invocation of local objects.

Security and Protection in Timor Programs.

“…Because Timor objects and processes are automatically persistent [7,8], and since the protection mechanisms described can function not only at the level of file objects but also at the level of the local objects which they contain, Timor can be used not only as an OO programming language but also as an object oriented database language, allowing highly protected databases to be developed and used with fine grained control at the level of the individual objects within the database. …”

“…As described in [8] Timor persistent threads can use a powerful authentication technique for checking the identities of users as they log in. This technique was first implemented for the persistent processes in the MONADS system [3] and is also included in the SPEEDOS operating system [1].…”

“…The Timor concept of persistent objects is described in detail in [7]. Activity in a Timor environment occurs via threads, which are stored in persistent process objects [8]. A persistent process object, which may have multiple threads that can be dynamically created and deleted, can persist between logouts and logins of its associated user, as will be described in more detail below.…”

Types and Co-Types in Timor.

“…Timor provides the programmer with the appearance of a distributed persistent virtual memory environment [6,7], which completely hides the existence of conventional file systems and remote computers. We now briefly review how objects are defined and accessed in this memory environment 1 .…”

“…This characterises a supertype variable or parameter to which a value, reference or capability of the appropriate type can be assigned. See [6,7] for a further discussion of persistence and of these concepts.…”