Disabling Akonadi:
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==Desktop Search and Semantic Desktop==
==Desktop Search and Semantic Desktop==
−
Most users who freshly install KDE are wondering what functionality the following four pieces of software are able
to
offer. Most features are still somehow hidden under the hood and yet not many applications featured in the KDE SC are using these interfaces. This chapter intends to first explain the features and then convince the user of the power these tools offer once properly integrated into KDE. The following sections are more or less a roughly shortened version of
[http://
thomasmcguire
.
wordpress
.
com
/
2009
/
10/03/akonadi-nepomuk-
and
-strigi-explained/ this blogpost]
.
+
According
to [http://
en
.
wikipedia
.
org
/
wiki
/
Semantic_desktop Wikipedia], ''"the Semantic Desktop is a collective term for ideas related to changing a computer's user interface
and
data handling capabilities so that data is more easily shared between different applications or tasks and so that data that once could not be automatically processed by a computer can be (automatically processed)
.
"''
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===Soprano===
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The KDE implementation of this concept is tied to (as of KDE 4.10) two major pieces of software, Akonadi and Nepomuk. Between the two of them, these programs look at your data and make an easily searchable index of it. The idea behind these pieces of software is to make your system "aware" of your data and give it context using meta-data and user-supplied tags.
−
Soprano
is a
library for Qt that is able to process
RDF
data
.
This is semantic data
.
Semantic data
is
a special kind of metadata which is much more flexible than metadata you might know
from
MP3-Tags or Meta
-
Tags
in
HTML since RDF data more resembles
the
structure of
a
spoken sentence
,
thus allowing
a
much wider field of ways dealing
with
them
. Soprano
stores semantic
data
in a backend
and
allows low level access to this data
.
+
+
Soprano and Virtuoso are two dependencies of the Nepomuk Semantic Desktop. Since the relationship between the two major components and their dependencies is not very clear, the following sections try to shed some light on their inner workings.
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+
===
Virtuoso and
Soprano===
+
+
The database used to store all the metadata used by the semantic desktop
is a
''[http://en.wikipedia.org/wiki/Resource_Description_Framework Resource Description Framework (
RDF
)]'' database called Virtuoso
.
Internally, Virtuoso may be looked as a relational database
.
(A [https://en.wikipedia.org/wiki/Relational_model relational database]
is
different
from
a traditional single
-
table based database
in the
sense that it uses multiple tables related by
a
single key in order to store data.) It is currently controlled by OpenLink
,
and is available under commercial and an open source license.
+
+
From the [http://techbase.kde.org/Projects/Nepomuk/ComponentOverview#Soprano KDE Techbase], ''Soprano is
a
Qt abstraction over databases. It provides a friendly Qt-based API for accessing different RDF stores. It currently supports 3 database backends - Sesame, Redland and Virtuoso. The KDE Semantic Stack only works
with
Virtuoso
. Soprano
also provides additional features such as serializing, parsing RDF
data
,
and
a client server architecture that is heavily used in Nepomuk
.
''
===Nepomuk===
===Nepomuk===
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Nepomuk is
somehow
the
glue between Soprano
and
the KDE Desktop
and
thus
the
user
.
Nepomuk
allows to
tag
the
files with
various
entries
and
offers an API for
the
applications featured
in KDE
SC
.
It
is enabled by default.
Nepomuk
can be turned on and off in
+
Nepomuk
stands for "Networked Environment for Personal, Ontology-based Management of Unified Knowledge". It
is
what allows all
the
tagging
and
labeling of files as well to take place
and
also serves as the way to actually read
the
Virtuoso databases
.
It provides an API to application developers which
allows
them
to
read the data collected by it.
+
+
In the past, the "Strigi" service was used to collect data about
the various
files present on the system. However, due to many reasons, the most important of them being CPU
and
Memory usage, Strigi was replaced by a homegrown indexing service which is integrated with Nepomuk-Core.
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+
For further information about Nepomuk, [http://techbase.kde.org/Projects/Nepomuk/ComponentOverview#Nepomuk_Components this page] is a good resource. However, some of
the
information
in
the previous page has been rendered outdated according to [http://vhanda.in/blog/2012/11/nepomuk-without-strigi/ this blog post].
+
+
====Using and configuring Nepomuk====
+
+
In order to search using Nepouk on the
KDE
desktop, press '''ALT+F2''' and type in your query
.
Nepomuk
is enabled by default.
It
can be turned on and off in
System Settings -> Desktop Search
System Settings -> Desktop Search
−
Nepomuk has to keep
the trace
of a lot of files
, because of
that is recommended to increase the number of files that can be watched with inotify
,
to do that
:
+
Nepomuk has to keep
track
of a lot of files
. It is for this reason
that
it
is recommended to increase the number of files that can be watched with inotify
. In order
to do that
this command is a good option.
sysctl fs.inotify.max_user_watches=524288
sysctl fs.inotify.max_user_watches=524288
−
To do it
persistant
:
+
To do it
persistently
:
echo "fs.inotify.max_user_watches = 524288" >> /etc/sysctl.conf
echo "fs.inotify.max_user_watches = 524288" >> /etc/sysctl.conf
−
And restart
Nepomuk.
+
Restart
Nepomuk
to see the changes
.
====KDE without Nepomuk====
====KDE without Nepomuk====
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==== Disabling Akonadi ====
==== Disabling Akonadi ====
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See [http://userbase.kde.org/Akonadi#Disabling_the_Akonadi_subsystem section in KDE userbase].
+
See
this
[http://userbase.kde.org/Akonadi#Disabling_the_Akonadi_subsystem section in
the
KDE userbase].
==== Database configuration ====
==== Database configuration ====
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====Running KDE without Akonadi====
====Running KDE without Akonadi====
The package {{AUR|akonadi-fake}} is a good option for those who wish to run KDE without Akonadi.
The package {{AUR|akonadi-fake}} is a good option for those who wish to run KDE without Akonadi.
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===Strigi Search===
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Strigi is another way of feeding data into Nepomuk. It preferably indexes the users home-folder. Indexing means that it not only gathers filenames but also information about your music collection or tagged downloads you did with Kget. The Strigi search is also integrated into KDE's launcher, which can be accessed via {{Keypress|Alt+F2}}.
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By default, Dolphin has a search bar on top-right where you may type what you want to be found from Strigi's index.
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{{Note | Strigi has implications for resource usage on your computer - CPU, memory, disk access, disk space, battery life. If Strigi is too resource-hungry for you, you can turn it off in "'''System Settings -> Desktop Search'''". }}
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Strigi folder indexing can be configured in:
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System Settings -> Desktop Search -> Desktop Query -> Customize index folders…
==Phonon==
==Phonon==