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## Package edu.utah.janosvm.sys

Provides the java interface to the JanosVM Team facilities.

See:
Description

Interface Summary
ManagedExportable | Declares that a subclass of Exportable needs to be explicitly released when it is revoked.
PersistentExport | Indicates an Exportable is to be kept alive even though it isn't imported by anyone at the moment.
TemporaryExport | Indicate that an exported object is only alive as long as it is imported by someone.

Class Summary
ConfigFile | Provides basic access to the configuration file.
Exportable | Base class for objects exported from teams.
ExportManager | Tracks the importables associated with a single exportable.
Importable | An Importable is a safe, cross-process reference to a remote "Exportable" object.
List | Root for a doubly linked list.
ListNode | Doubly linked list node.
PortAuthority | Manages the imports and exports of a team.
Team | Peer object for a TeamBackEnd.
TeamEvent | Simple class that describes a team related event.
TeamHandle | Provides a safe handle to a Team.
TeamList | An Importable for TeamListBackEnd that just provides a path for callbacks.
TeamReservation | Record a reservation with another team.
VMInstance | Functions specific to the VM as a whole.

Exception Summary
DeadTeamException | Exception thrown when a visit cannot be done because one of the teams involved is dead.
DuplicateExportException | Exception thrown when trying to export a object with an 'id' that has already been used.
NoSuchExportException | Exception thrown when trying to import an object that doesn't exist.
TeamEjectionException | Exception thrown when a thread is forcefully thrown from a team.

Error Summary
SegmentationFaultError | Indicates that an invalid cross-process pointer was dereferenced.

## Package edu.utah.janosvm.sys Description

Provides the java interface to the JanosVM Team facilities.

There are three basic abstractions provided in this package: Teams, Importables and Exportables. The Team is the basis of separation and control in the JanosVM, it is the hook from which resource controls and access controls are hung. Importables and Exportables represent the two views of an object that is shared between teams: the owner's (Exportable) and the user's (Importable).

## Teams

A team is a context for execution. It provides the resource limits for threads executing in that context. Most notably the Team embodies the memory available to threads in that context. Another resource associated with a Team is the root name space for classes within the team.

## Importables and Exportables

The JanosVM supports separate heaps and garabage collection for each Team. This means the GC thread for team A can run independently of the GC in team B, and that the GC thread for each team looks only at its local roots when performing a GC. References between heaps (say from team A to team B) need to be counted without requiring the GC for team A to look at every other heap in the system. We accomplish this by making all inter-heap references be explicitly managed. This is what Importables and Exportables do. They act as proxies to keep alive local objects referenced remotely, even if the local heap has no references to the object.

### Visits and Activations

Importables and Exportables do not magically solve all the problems with inter-team references. There are still many restrictions that must be enforced by the code running on the JanosVM (this is why the JanosVM isn't a JavaOS on its own, its just a JVM that can host a JavaOS).

See Also:
  `Team`, `TeamHandle`, `TeamBackEnd`, `Importable`, ``

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This documentation is Copyright (C) 2000-2001 The University of Utah. All Rights Reserved. See the documentation license for distribution terms and restrictions.
Documentation, software, and mailing lists for the JanosVM can be found at the Janos Project web page: http://www.cs.utah.edu/flux/janos/
Generated on Jun 1, 2001