Subject: [VCARDDAV] Terminology Issues - mid/high-level devices

From: "Darryl Champagne" <[email-masked]>
Date: Tue, 8 Jul 2008 22:19:26 -0400

In previous emails I defined "Sync Anchors", "Slow Sync", "Object Level
Duplicate Detection", "Field Level Duplicate Detection", "Sync
Meta-Information", and "low-end consumer phone".

For the next step up from a low-end consumer phone, we get to higher end
phones, like the iPhone, Blackberries, high-end Nokias, Windows Mobile
devices, and even PCs.

I don't generally use a specific term for these, other than distinguishing a
PC, which can act as both a client and a server, from a high-end phone.

As we progress forward in time, I do expect these to fully support UIDs,
PIDs, and REV.  Support for field level change tracking would be possible,
by comparing the contact information from the time of the last sync, with
the current state.

I also expect these devices to continue to lose Sync Meta-Information in
cases of client upgrade or multiple clients, or perhaps rarely due to a
client error.  For example, the ActiveSync client on a Windows Mobile device
is spectacularly uncooperative with a standalone SyncML client.  Similarly,
I can store lots of data into an Outlook managed address book, but a copy of
the original vCard will only reside in a particular instance of a sync
client, or as custom data that only a particular vendor will be able to
extract.

These devices should not require slow syncs very often (well, except for
trying to use both ActiveSync and SyncML together), but they will
occasionally happen.  When it is not a slow sync, they should be able to
support field level change tracking.

The last category of capability is "High-end Server".  This is the internet
portal run by the carrier, or an enterprise server.  In general, these
support everything to some extent (although they all tend to drop some
things).

However, these frequently have a characteristic that people may not know
about - they expect a certain amount of client turnover. This might be
people trying out the service and then stopping, or devices that are lost
and no longer sync, and so on.  While storage is cheap, it still adds up
when you are talking very large databases, servers, and so on.  Any
reasonable implementation is going to desire to clean up periodically,
especially data related to devices that have not performed a sync in an
extended period of time (especially since they might never do another sync).

What generally will happen is that after some period of time, all Sync
Meta-information specific to a particular device will be erased / recovered.
The actual address book will be kept much longer, since that may be used by
other devices (or for backup and restore), but eventually even that will be
archived or deleted.  Frequently, this works perfectly, but at least some of
the time, that device will start syncing again - such as the person who gets
a new toy, eventually tires of it, gives it away or sticks it in a drawer,
and goes back to their original device.  As another example, when I am
outside the US, my Windows Mobile CDMA device can no longer sync.  After an
extended trip, it may end up doing a slow sync because of the server losing
information, rather than it.

Because of these server constraints, this may (rarely) force additional slow
syncs upon all the clients.

Thanks,
dgc
--
Darryl G. Champagne
Technology Evangelist
Funambol
AIM/Y!/Skype: dgc03052
ph: +1 (603) 424-0323     Mob: +1 (603) 440-3621 (+ SMS)
[email-masked]          http://www.funambol.com 

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