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Re: Jini Distributed Leasing Specification (was Re: timeout types)

From: Kaelin Colclasure <kaelin@everest.com>
Date: Mon, 24 Jan 2000 12:01:08 -0800
Message-ID: <03d201bf66a5$c0de3bd0$0201a8c0@everest.com>
To: "Jim Whitehead" <ejw@ics.uci.edu>, <w3c-dist-auth@w3.org>
----- Original Message -----
From: Jim Whitehead <ejw@ics.uci.edu>
To: Kaelin Colclasure <kaelin@everest.com>; <w3c-dist-auth@w3.org>
Sent: Monday, January 24, 2000 11:47 AM
Subject: RE: Jini Distributed Leasing Specification (was Re: timeout types)


> Well, I was not familiar with Jini leases, so I took a quick look through
> the spec. you referenced.  As near as I can tell, there are many
> similarities between the semantics for Jini leases and WebDAV locks.  Jini
> leases allow an object to request a lease that lasts forever, or for a
> specific time period, similar to WebDAV locks which can be requested for a
> specific time period in seconds, or with the value "Infinite".  Jini
leases
> can be refreshed, as can WebDAV locks, by re-requesting the lock. Jini
> leases can be canceled before the time period ends, as can WebDAV locks,
> using the UNLOCK method.
>
> Was there some specific Jini lease semantic that you particularly think
> WebDAV would benefit from?

Yes.

 a) You can request an "infinite" lease, but you must be prepared for the
    server to return to you instead a finite lease. You must then renew that
    lease before it expires if you want it to persist without interruption.
 b) The renewal of the lease is an explicit action on the part of the
client,
    and is required to occur within a specific time interval. There is no
    implicit anything.

This is, IMHO, significantly less complicated to implement robustly and
correctly than implicit renewal. And of course, truly infinite locks are
highly suspect in a distributed environment. It could be argued that
leases shouldn't permit them at all -- but it suffices to interpret
"infinite" to mean "the longest period a server chooses to tolerate
possibly holding a resource for a client that's never coming back."

-- Kaelin

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Received on Monday, 24 January 2000 15:05:56 GMT

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