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Event Delivery Abstractions for Mobile Computing
B.R. Badrinath and Girish Welling, Rutgers DATAMAN
Distinguishes monitored events (poll for parameter of interest to
leave specified window) from triggered events (low-level state
change, i.e. insert PC card), and defines a language-level mechanism
based on C++ objects for event registration, delivery, and handling.
- Each app may define several EventObjects or MonitorObjects (by
subclassing from base classes) that
register interest in specific events. Event is delivered once to
each registered object.
- Small amount of data is piggybacked onto event delivery.
Not clear how to provide substantially more data,
esp. since event handlers are encapsulated objects.
- Central Event Registrar provides low-level event capture and
encapsulates them for delivery. OS-specific peculiarities of
dealing with events are encapsulated here.
Proposes a standard abstraction for event delivery; potentially many
uses for this model (interactive groupware, network events, mobility
- Implementation is in Mach 3.0; makes use of Mach threads (for
monitor objects) and Mach objects, and C++ class mechanism for
creating objects. I.e. all the hard work is really already done
in the OS. Not appropriate for portables.
- Future work includes determining what minimal OS functionality is
necessary to support their abstraction. In my view, this is the
interesting question, and the one I expected the paper to answer.
- Future work includes abstractions for object and thread
migration. Not clear what the relationship is to this paper, or
whether they will again punt to the OS and just encapsulate the
OS-provided behavior in a class. I mean, anyone can do that.
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