Preface — The Synchronization Problem
ownCloud offers a Free software solution to synchronize your files across different devices. I’ve been working on a KDE Plasma client for this server technology. In this article, after giving a bit of background of the problem, I explain the design concepts behind the new ownCloud Plasma client and demonstrate how it works and integrates with different Plasma workspaces.
I’ve been looking for a good solution to synchronize my data across different devices I use forever. The need arose when I got my first laptop (next to my desktop machine): I wanted to be able to work on my projects on both devices without having to manually copy files between the machines. It turned out to be actually quite a hard problem: Sure, you can work on your stuff on a remote machine, and thereby always work on one version of a certain file. But what happens when you’re offline? I needed files to be synched, and was looking for a more or less automated that worked both offline and online. I took a look at the Coda Filesystem, which seemed to solve this problem well, for others at least. It was a bit of a pain to set up (and understand how it exactly worked), but after a bit of fiddling, I had copies of my stuff on different machines. It seemed to work initially, but later turned out to be a little bit too brittle for my use cases (I don’t quite recall the details, but eventually, I gave up on it because it meant more or less constant maintenance, and still it wasn’t quite as bullet proof as I had hoped it would be.
At university (where I both studied and worked for quite a while), we often used SVN for collaboration. There’s value to using the same tools in more places, so I put all my files into an SVN repository and used that for synchronization. Eventually, I moved these private data repositories to Git, as I grew more comfortable with this tool and it allowed useful things like offline commits and synching between “client devices”, not just between client and server. Not an automatic process, also not the most beautiful solution to the problem as it wasn’t quite as automated as I’d have liked it to be. Also, as computing became more portable, I needed something that would also blend in well with with all the devices that produce, collect and are supposed to carry my data.
My problem is of course not unique to me: File synchronization plays an ever more important role, Internet connections become faster and more ubiquitous, the device spectrum expands. Where people have been using one computer for all their electronic communication and computing needs, it now spreads across different devices, desktops, laptops, tablets, smartphones, media centers, and likely many more form factors we can only dream of today (or maybe not even that!). Devices jumping between network infrastructures doesn’t make it easier, and the most flexible solution seems to a central server – multiple clients model. ownCloud offers exactly that, it’s Free software (licensed under the AGPL), is easy to setup and runs on bog standard LAMP setups. Its server side performs well enough to be able to run it on even woefully underpowered hardware such as NAS systems or other embedded devices. More importantly, it gives you full control over your data, which is nice and important for private use, and often a hard requirement for institutional use cases, such as document management and sharing in a company.
I’ve been keeping a keen eye on ownCloud for a while, and, somewhere in its 3.x cycle, I decided to set up owncloud on my private server and started experimenting with it. Installation was quite easy, and the desktop client Mirall seemed to work well initially.
My own Plasma Cloud
After using it for a bit, I ran into a few problems, some of them simple bugs (most of which seem to have been fixed), some UI issues, and also a lack of integration. Mirall’s UI is a “standard systray application”, it always sits there in the system tray, shows its status and allows you to set up directories (“Folders”) for synchronization with the ownCloud server. Mirall’s UI, however bears all the traits of a “traditional” desktop application: It’s unsuitable for touch interfaces, abuses the system tray as task switcher and overall not quite up to modern UI standards we use in Plasma. As Mirall is geared towards portability (it’s the official desktop client for Linux, Mac and Windows), it lacked good integration into Plasma — the usual lowest common denominator problem). What crossed my mind was redoing the UI using Plasma technologies, thereby updating its Look & Feel and at the same time making it suitable for touch interfaces, such as Plasma Active, KDE’s device-independent user experience.
Collaboration for a new design
At Akademy this summer, Klaas (who works for ownCloud Inc. on Mirall), me and a few others sat down to talk about better integration of ownCloud into the Plasma Desktop. ownCloud being a project very close to KDE (it sprang from the KDE community, had developer meetings and travel expenses funded by the KDE e.V., partly runs on KDE infrastructure, and some KDE developers are also working on ownCloud), that seemed like the right thing to do. In a BoF session, we sat down, talked about what we’d like to see improved and started designing a KDE Plasma client for ownCloud, based on the Mirall code base. What we came up with can be explained as follows:
- The UI bits and synchronization code from Mirall will be split, and the sync mechanism will be split out into a shared library
- The shared library is used by a daemon, which on the one hand takes care of keeping files in sync, and one other side exports a DBus control interface
- A Plasma widget shows synchronization status and allows basic control like disabling syncing
- A System Settings module allows to setup synchronization of the ownCloud client
- A Plasma Active Settings module allows to set up the ownCloud client from your mobile device
With this solution, we can cover a range of devices, providing a consistent operation and Look & Feel and share code to keep development costs down. Doing the UI components in Plasma Quick (Plasma and KDE technologies + Qt Quick’s QML), we can the maximum amount of code across different devices, and create a modern UI that adapts itself to form factors and input methods (meaning it will work well on both, mouse/keyboard driven target devices, as well as touch screens). As a bonus, doing the UI in Plasma Quick means it’s easy to hack, easy to contribute for others.
Having a clear idea how we want to go forward, and an agreed-upon plan de campagne, we sat down to implement all the designed goodness. Klaas was quick to split out the synchronization mechanism from ownCloud into its own shared library, and I started working on the bits needed for the Plasma client: The sync daemon, the UI components used by the configuration modules and the Plasmoid, and of course those UIs themselves. Progress has been quite good, I quickly got the synchronization daemon up and running, and could move to implementing the various pieces of user interface needed.In the process, I’ve created a bunch of patches to Mirall, some of them merged, others still in the review queue. They’re mostly fairly trivial, splitting out a bit of QWidget-based remainders from the daemon (and thereby cutting down its size considerably), and extending the API (in a backwards compatible way) to allow better status display and control from the user interface “satellites”.
File synchronization is of course the main feature here. This already works reasonably well, including setting up of server and folders. The UI has a few problems here and there, but the important pieces are in place. The plan is to ship a first stable version with the release of Plasma Active 4 in March, which will also mark the availability of the desktop client.
How to make it all happen faster?
I’d be most grateful if distro packagers would pick the new ownCloud Plasma client up at this point, package it and allow users to test it (with the necessary warning signs of eating pet and firstborns attached, of course). There’s still quite a lot of work to do, but the basics work, and getting feedback helps me prioritize what to work on first to get this into the hands of our dear users.
Of course if you’re interested in contributing to the client directly (in the form of code, UI design, bug fixing, polishing, performance, etc, you’re also most welcome to do so. The code is currently hosted on Github (like other ownCloud subprojects, if you prefer a Free software solution, we can clone it on KDE infrastructure as well, and sync our upstream changes as needed to Github). In order to build it, check out and build the “plasmaclient” branch. This will install the various components to your system. After running “kbuildsycoca4″ (or relogging in), you can enable the Plasma widget through your notification area configuration.