[dot] OpenSync - Synching on the Free Desktop

[Dot Stories]

URL: http://dot.kde.org/1148063569/

From: Arne Babenhauserheide <arne_bab at web.de>
Dept: synching-any-fruit-on-any-tree
Date: Friday 19/May/2006, @11:32

OpenSync - Synching on the Free Desktop
=======================================

   "It's the first time I feel good when thinking about synching.",
Cornelius, one of the OpenSync developers.  This interview intends to
give you some insight into OpenSync, the upcoming free unified synching
solution for the free desktop.  Arne interviews the developers from
OpenSync and KDE PIM, Cornelius Schumacher, Armin Bauer and Tobias
Koenig.


  I. BASICS

     As you are now getting close to version 1.0 of OpenSync, which is
expected to become the new synchronisation framework for KDE and other
free desktops, we are quite interested in the merits it can provide for
KDE users and for developers, as well as for the Open Source Community
as a whole. So there's one key-question before I move deeper into the
details of OpenSync:

     What does OpenSync accomplish, that was not done before?

     Cornelius: First of all it does its job of synchronizing data like
addressbooks and calendars between desktop applications and mobile
devices like PDAs and cell phones.

     But the new thing about OpenSync is that it isn't tied to a
particular device or a specific platform. It provides an extensible and
modular framework which is easy to adopt for application developers and
people implementing support for syncing with mobile devices.

     OpenSync is also independent of the desktop platform. It will be
the common syncing backend for at least KDE and GNOME and other projects
are likely to join. That means that the free desktop will have one
common syncing solution. This is something really new.

     How do the end-users profit from using synching solutions which
interface with OpenSync as their framework?

     Cornelius: First, the users will be able to actually synchronize
all their data. By using one common framework there won't be any
"missing links", where one application can sync one set of devices and
another application a different one. With OpenSync all applications can
sync all devices.

     Second, the users will get a consistent and common user interface
for syncing across all applications and devices. This will be much
simpler to use than the current incoherent collection of syncing
programs you need if you have more than the very basic needs.

     How does OpenSync help developers with coding?

     Cornelius: It's a very flexible and well-designed framework which
makes it quite easy for developers to add support for new devices and
new types of data. It's also very easy to add support for OpenSync to
applications.

     The big achievement of OpenSync is that it hides all the gory
details of syncing from the developers who work on applications and
device support. That makes it possible for the developers to concentrate
on their area of expertise without having to care what's going on behind
the scenes.

     I have written quite a lot of synchronization code in the past.
Trust me, it's much better, if someone just takes care of it for you,
and that's what OpenSync does.

     Tobias: Another point to mentioned is the python wrapper for
OpenSync, so you are not bound to C or C++, but can develop plugins in a
high level scripting language.

     Why should producers of portable devices get involved with your
team?

     Cornelius: OpenSync will be the one common syncing solution for the
free desktop. That means there is a single point of contact for device
manufacturers who want to add support for their devices. That's much
more feasible than addressing all the different applications and
solutions we had before. With OpenSync it hopefully will become
interesting for manufacturers to officially support Linux for their
devices.

     Do you also plan to support applications of OpenSync in proprietary
systems like OSX and Windows?

     Cornelius: OpenSync is designed to be cross-platform, so it is able
to run on other systems like Windows. How well this works is always a
question of people actually using and developing for this system. As far
as I know there isn't a real Windows community around OpenSync yet. But
the technical foundation is there, so if there is somebody interested in
working on a unified syncing solution on Windows, everybody is welcome
to join the project.

     What does your synchronisation framework do for KDE and for
KitchenSync in particular?

     Cornelius: OpenSync replaces the KDE-specific synchronization
frameworks we had before. Even in KDE we had several separate syncing
implementations and with OpenSync we can get replace them with a common
framework. We had a more generic syncing solution in KDE under
development. This was quite similar from a design point of view to
OpenSync, but it never got to the level of maturity we would have
needed, because of lack of resources. As OpenSync fills this gap we are
happy to be able to remove our old code and now concentrate on our core
business.


 II. WHO, HOW AND WHY?

     What was your personal reason for getting involved with OpenSync?

     Cornelius: I wrote a lot of synchronization code in the past, which
mainly came from the time where I was maintaining KOrganizer and working
on KAddressBook. But this always was driven by necessity and not
passion. I wanted to have all my calendar and contact data in one place,
but my main objective was to work on the applications and user
interfaces handling the data and not on the underlying code
synchronizing the data.

     So when the OpenSync project was created I was very interested. At
GUADEC in Stuttgart I met with Armin, the maintainer of OpenSync, and we
talked about integrating OpenSync with KDE. Everything seemed to fit
together quite well, so at Linuxtag the same year we had another meeting
with some more KDE people. In the end we agreed to go with OpenSync and
a couple of weeks later we met again in Nuernberg for three days of
hacking and created the KDE frontend for OpenSync. In retrospect it was
a very pleasant and straightforward process to get where we are now.

     Armin: My reason to get involved (or better to start) OpenSync was
my involvement with its predecessor Multisync. I am working as a system
administrator for a small consulting company and so I saw some problems
when trying to find a synchronization solution for Linux.

     At that point I joined the Multisync project to implement some
plugins that I thought would be nice to have.  After some time I became
the maintainer of the project. But I was unhappy with some technical
aspects of the project, especially the tight coupling between the
syncing logic and the GUI, its dependencies on GNOME libraries and its
lack of flexibility.

     Tobias: Well, I have been a KDE PIM developer for several years
now, so there was no way around getting in touch with synchronization
and KitchenSync. Although I liked the idea of KitchenSync, I hated the
code and the user interface [...]. So when we discussed to switch to
OpenSync and reimplementing the user interface, I volunteered
immediately.

     Can you tell us a bit about your further plans and ideas?

     Cornelius: The next thing will be the 1.0 release of OpenSync. We
will release KitchenSync as the frontend in parallel.

     Armin: There are of course a lot of things on my todo and my
wishlist for OpenSync. For the near future the most important step is
the 1.0 release, of course, where we still have some missing features in
OpenSync as well as in the plugins.

     One thing I would really like to see is a Thunderbird plugin for
OpenSync. I use Thunderbird personally and would really like to keep my
contacts up to date with my cellular, but I was not yet able to find the
time to implement it.

     Tobias: One thing that would really rock in future versions of
OpenSync is an automatic hardware detection mechanism, so when you
plugin your Palm or switch on your bluetooth device, OpenSync will
create a synchronization group automatically and ask the user to start
syncing. To bring OpenSync to the level of The Syncing Solution [tm] we
must reduce the necessary configuration to a minimum.

     What was the most dire problem you had to face when creating
OpenSync and how did you face it?

     Cornelius: Fortunately the problems which I personally would
consider to be dire are solved by the implementation of OpenSync which
is well hidden from the outside world and [they are] an area I didn't
work on ;-)

     Armin: I guess that I am the right person to answer this question
then :)

     The most complicated part of OpenSync is definitely the format
conversion which is responsible for converting the format of one device
to the format that another device understands.

     There are a lot of subsystems in this format conversion which makes
it so complex, like conversion path searching, comparing items,
detection of mime types and last but not least the conversion itself. So
this was a hard piece of work.

     What was the greatest moment for you?

     Cornelius: I think the greatest moment was when, after three days
of concentrated hacking, we had a first working version of the KDE
frontend for OpenSync. This was at a meeting at the SUSE offices in
Nuernberg and we were able to successfully do a small presentation and
demo to a group of interested SUSE people.

     Armin: I don't remember a distinct "greatest moment". But what is a
really great feeling is to see that a project catches on, that other
people get involved, use the code you have written and improve it in
ways that you haven't thought of initially.

     Tobias: Hmm, also hacking on OpenSync/KitcheSync is much fun in
general, the greatest moment was when the new KitchenSync frontend
synced two directories via OpenSync the first time. But it was also cool
when we managed to get the IrMC plugin working again after porting it to
OpenSync.

     As we now know the worst problem you faced and your greatest
moment, the only one missing is: what was your weirdest experience while
working on OpenSync?

     Cornelius: Not directly related to OpenSync, but pretty weird was
meeting a co-worker at the Amsterdam airport when returning from the
last OpenSync meeting. I don't know how high the chance is to meet
somebody you know on a big random airport not related at all to the
places where you or the other person live, but it was quite surprising.

     Tobias: Since my favorite language is C++, I was always confused
how people can use plain C for such a project, half the time your are
busy with writing code for allocating/freeing memory areas. Nevertheless
Armin did a great job and he is always a help for solving strange C
problems :)


III. DEVICES AND PROGRAMS

     Now I'd like to move on to some more specific questions about
current and planned abilities of OpenSync. As first, I've got a personal
one: I have an old iPod sitting around here. Can I or will I be able to
use a program utilizing OpenSync to synchronize my calendars, contacts
and music to it?

     Cornelius: I'm not aware of any iPod support for OpenSync up to
now, but if it doesn't exist yet, why not write it? OpenSync makes this
easy. This is a chance for everybody with the personal desire to sync
one device or another to get involved.

     Armin: I dont think that there is iPod support yet for OpenSync.
But it would definitely be possible to use OpenSync for this task. So if
someone would like to implement an iPod plugin, I would be glad to help
:)

     Which other devices do you already support?

     Cornelius: At this time, OpenSync supports Palms, SyncML and IrMC
capable devices.

     Which programs already implement OpenSync and where can we check
back to find new additions?

     Cornelius: On the application side there is support for Evolution
[GNOME] and Kontact with KitchenSync [KDE] on the frontend side and the
backend side and some more. I expect that further applications will
adopt OpenSync once the 1.0 version is released.

     Armin: Besides Kitchensync there already is a command line tool and
a port of the multisync GUI. Aside from the GUIs, I would really like to
see OpenSync being used in other applications as well. One possibility
for example would to integrate OpenSync into Evolution to give users the
possibility to synchronize their devices directly from this application.
News can generally be found on the OpenSync website.
 [http://www.opensync.org]

 IV. TECHNICAL DIVE

     So far for questions for users. I think it is time to give the
developers something to devour, too. I'll keep this as a short
twice-fold technical dive before coming to the takeoff question, even
though I'm sure there's information for a double-volume book on
technical subleties.

     As first dive: how did you integrate OpenSync in KitchenSync,
viewed from the coding side?

     Cornelius: OpenSync provides a C interface. We wrapped this with a
small C++ library and put KitchenSync on top. Due to the object oriented
nature of the OpenSync interfaces this was quite easy.

     Recently I also started to write a D-Bus frontend for OpenSync.
This also is a nice way to integrate OpenSync which provides a wide
variety of options regarding programming languages and system
configurations.

     And for the second, deeper dive: Can you give us a quick outline of
those inner workings of OpenSync, from the developers view, which make
OpenSync especially viable for application in several different desktop
environments?

     Cornelius: That's really a question for Armin. For those who are
interested I would recommend to have a look at the OpenSync website.
There is a nice white paper
[http://www.opensync.org/file/trunk/docs/OpenSync-WhitePaper.pdf?format=raw]
about the internal structure and functionality of OpenSync.

     Armin: OpenSync consists of several parts:

     First there is the plugin API which defines what functions a plugin
has to implement so that OpenSync can dlopen() it. There are 2 types of
plugins:

     A sync plugin which can synchronize a certain device or application
and which provides functions for the initialization, handling the
connection to a device and reading and writing items. Then there is a
format plugin which defines a format and how to convert, compare and
detect it.

     The next part is a set of helper functions which are provided to
ease to programming of synchronization plugins. These helper functions
include things like handling plugin config files, HashTables which can
be used to detect changes in sets of items, functions to detect when a
resync of devices is necessary etc.

     The syncing logic itself resides in the sync engine, which is a
separate part. The sync engine is responsible for deciding when to call
the connect function of a plugin, when to read or write from it. The
engine also takes care of invoking the format conversion functions so
that each plugin gets the items in its required format.

     If you want more information and details about the inner workings
of OpenSync, you should really visit the opensync.org website or ask its
developers.


  V. TAKEOFF

     To add some more spice for those of our readers, whose interest you
just  managed to spawn (or to skyrocket), please tell us where they can
get more information on the OpenSync Framework, how they can best meet
and help  you and how they can help improving sync-support for KDE by
helping OpenSync.

     Cornelius: Again, the OpenSync web site is the right source for
information. Regarding the KDE side, the kde-pim at kde.org mailing list is
probably the right address. At the moment the most important help would
be everything which gets the OpenSync 1.0 release done.

     [And even though] I already said it, it can't be repeated too
often: OpenSync will be the one unified syncing solution for the free
desktop. Cross-device, cross-platform, cross-desktop.

     It's the first time I feel good when thinking about syncing ;-).

     Armin: Regarding OpenSync, the best places to ask would be the
opensync mailing lists at sourceforge or the #opensync irc channel on
the freenode.net servers.

     There are always a lot of things where we could need a helping hand
and where we would be really glad to get some help. So everyone who is
interested in OpenSync is welcome to join.

     Many thanks for your time!

     Cornelius: Thanks for doing the interview. It's always fun to talk
about OpenSync, because it's really the right thing.

     Armin: Thank you for taking your time and doing this interview. I
really appreciate your help!

     Tobias: Thanks for your work. Publication and marketing is
something that is really missing in the open source community. We have
nice software but nobody knows ;)

     Further Information on OpenSync can be found on the OpenSync
Website.
 [http://www.opensync.org]
     This Interview was done by Arne Babenhauserheide
[http://draketo.de] in April 2006 via e-mail and KOffice
 [http://koffice.kde.org] on behalf of SpreadKDE.org
[http://www.spreadkde.org] and the Dot [http://dot.kde.org].  It is
licensed under the  cc-attribution-sharealike-license.
 [http://creativecommons.org/licenses/by-sa/2.5/]