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Akonadi, Nepomuk and Strigi explained

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KDE

Tobias recently blogged about Nepomuk, and from the comments it seems that people are a bit in the dark about what Akonadi, Nepomuk and Strigi actually do and how they interact with each other. So if you want to understand those technologies, read on! This blog post is an attempt to clear things up a bit.

Soprano

Let me start with Soprano. Soprano is a Qt library for accessing semantic storage (RDF). In many ways, Soprano can be compared to the QtSql module, the key difference is that QtSql accesses relational data with SQL as the query language, whereas Soprano accesses semantic data with SPARQL as the query language.

Semantic Data

But what is semantic data, and what is the difference to relational data? You probably all know relational databases, which use tables to store data. Semantic databases, on the other hand, use statements, also sometime referred to as sentences, to store data. Statements consist, just like real-world sentences, of a subject (noun), a predicate (verb) and an object. By storing many sentences in a database, one can create a big network of data. The best way to make this clear is probably by examples, so here are some:

rest here




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today's leftovers

  • DRM display resource leasing (kernel side)
    So, you've got a fine head-mounted display and want to explore the delights of virtual reality. Right now, on Linux, that means getting the window system to cooperate because the window system is the DRM master and holds sole access to all display resources. So, you plug in your device, play with RandR to get it displaying bits from the window system and then carefully configure your VR application to use the whole monitor area and hope that the desktop will actually grant you the boon of page flipping so that you will get reasonable performance and maybe not even experience tearing. Results so far have been mixed, and depend on a lot of pieces working in ways that aren't exactly how they were designed to work.
  • GUADEC accommodation
    At this year’s GUADEC in Manchester we have rooms available for you right at the venue in lovely modern student townhouses. As I write this there are still some available to book along with your registration. In a couple of days we have to a final numbers to the University for how many rooms we want, so it would help us out if all the folk who want a room there could register and book one now if you haven’t already done so! We’ll have some available for later booking but we have to pay up front for them now so we can’t reserve too many.
  • Kickstarter for Niryo One, open source 6-axis 3D printed robotic arm, doubles campaign goal
    A Kickstarter campaign for the Niryo One, an open source 3D printed 6-axis robotic arm, has more than doubled its €20,000 target after just a couple of days. The 3D printed robot is powered by Arduino, Raspberry Pi, and Robot Operating System.
  • Linux Action Show to End Eleven Year Run at LFNW
    Jupiter Broadcasting’s long-running podcast, Linux Action Show, will soon be signing off the air…er, fiber cable, for the last time. The show first streamed on June 10, 2006 and was hosted by “Linux Tycoon” Bryan Lunduke and Jupiter Broadcasting founder Chris Fisher. Lunduke left the show in 2012, replaced by Matt Hartley, who served as co-host for about three years. The show is currently hosted by Fisher and Noah Chelliah, president of Altispeed, an open source technology company located in Grand Forks, North Dakota.