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research:ambientrefs

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Ambient References

ambientrefs.jpg

Ambient references are a novel remote object reference mechanism. Remote object references are “pointers across the network” and are a frequently recurring abstraction in both distributed OO languages and distributed middleware. Ambient references are designed to refer to objects in mobile networks. What exactly constitutes a mobile network and how it differs from traditional, stationary networks is described elsewhere.

Motivation

One may wonder why new referencing abstractions are required for mobile networks. In order to motivate the need for new referencing abstractions at the language level, we list a number of desirable properties of remote references for mobile networks which current remote referencing abstractions do not offer:

  1. Provisional References: remote references should be able to point to remote objects which are “not yet available” in the network. This is founded on the observation that in mobile networks, ambient resources need to be discovered in the environment and will most likely be unavailable most of the time.
  2. Resilience to Partial Failure: remote references for mobile networks should be able to tolerate network disconnections because of the volatile connnections hardware phenomenon of mobile networks.
  3. Transitory Addressing: remote references in mobile networks should bind to (point to) objects based on what services that object provides, rather than based on a low-level UID, object-id, IP address or MAC address. Such low-level IDs preclude the reference from reconfiguring itself by rebinding to a different object providing the same or equally matching services.
  4. Group Communication: in mobile networks, one often wants to communicate with an entire group of objects. To this end, remote references should be introduced that automatically represent a set of (proximate) objects. Messages sent to such references are automatically multicast or broadcast to all objects in the set.
Design

Ambient references unify two concepts: they are both a peer-to-peer discovery channel and an asynchronous communication channel to a remote object.

Example Usage
Implementation

A detailed explanation of ambient references can be found in this technical report.

Further Reading

Ambient References: Addressing Objects in Mobile Networks. Tom Van Cutsem, Jessie Dedecker, Stijn Mostinckx, Elisa Gonzalez Boix, Theo D'Hondt, Wolfgang De Meuter. In Technical Report VUB-PROG-TR-06-10, Vrije Universiteit Brussel, 2006 [ download ]

research/ambientrefs.1151400670.txt.gz · Last modified: 2006/06/27 11:31 (external edit)