Nepomuk how-to

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Nepomuk provides the basis for managing all kinds of metadata on the KDE desktop. This ranges from manual annotations such as tags or comments over metadata extracted from files to metadata that is generated by applications automatically. Nepomuk makes it possible to relate any and all information artifact on the desktop or on the Web, with the goal to organize information more efficiently, and more closely to the way we associate items mentally. This page explains how to activate Nepomuk in Mandriva Linux 2010 edition and to discover the features it enables.


Nepomuk activation

Activation of Nepomuk and Strigi from the KDE System Settings

Nepomuk works only with the KDE desktop environment. Follow these steps to activate it in Mandriva Linux 2010:

  • Open the KDE system settings.
  • Double click the icon "Desktop search".
  • In case the Nepomuk checkbox is disabled, install the package soprano-plugin-sesame2 (choose the java-1.6.0-openjdk).
  • Check the Nepomuk box.
  • Check the Strigi check box.
  • In the "Advanced tab", select the folders containing files you want to get indexed by Strigi.
  • Hit the apply button. This will activate Nepomuk, load the Nepomuk ontologies into your personal information database, and launch the analysis of the checked folders by Strigi (metadata and text extraction).

Task management features

In order to benefit from the task management features, proceed as follow:

Task management plasmoid
Cross-applications task manager
  • Add the plasmoid titled "Task Management" to your taskbar.
  • Launch the task manager from the plasmoid.
  • Create a task.
  • By default, the current task is set to the one you just created. You can set a current task at the desktop level by selecting it in the "Current task" popup menu of the Task Management plasmoid.
  • From Konqueror: you can link Web pages you the newly created task by hitting the Task button in Konqueror's toolbar.
  • From Firefox: you can add the Firefox Nepotask plugin for linking Web pages to your current task.
  • Files can be linked to task either from the task manager or directly from Dolphin by selecting the entry "Action > Associate to task" of the context menu.
  • Open the task management application from the task plasmoid: you will see all the items linked to the current task in a uniform manner.
  • In Dolphin, hit Ctrl+L, enter "nepomuktree" in the location bar: this will display all your tasks and let you navigate accross them. You can add the location to the Dolphin Places for quickly accessing your tasks.

Semantic email

KMail enhanced with annotation capabilities
  • Install the kmail-nepomuk package (this will require to uninstall the default KMail packge). KMail-nepomuk is a slightly modified version of KMail which adds annotation capabilities to it.
  • Launch KMail.
  • You will be able to annotate your emails and to link them to existing tasks.
  • You will also get annotation suggestions for easing the creation of links with relevant entities of your knowledge base.

Semantic file dialog

Smart file dialog for navigating across files semantically
  • Open the file open dialog from any KDE application.
  • Hit the button "Semantic view".
  • Navigate across your files by selecting semantic filters: you should see filters related to your tasks or tags.

Tag browsing

  • Files can be tagged, rated and commented on from Dolphin, using the Dolphin information panel.
  • Web pages can be tagged and rated from Konqueror using the context menu.
  • Files can be browsed by tag from Dolphin by hitting "Ctrl+L" and enter "tags:/" in the location bar.


Nepomuk generic explorer: Nepomuk shell
  • Launch the Nepomukshell from a terminal by running the command "nepomukshell".
  • New classes can be created by hitting the "New Class" button (for instance, create a class Appartment, Song, Movie, etc.).
  • New instances can be created by hitting the "New Resource" button.
  • Resources can be annotated using the Nepomukshell annotation panel on the right side: it can be described, tagged, and linked to other resources using specific properties using the "Annotate" field (hit the left arrow for switching to the advanced annotation mode, then type a property name, then a value).

Text recognition in images

Image example - Text recognition demo
  • Install tesseract.
  • In Dolphin, right click an image containing some text, select the entry "Action > Annotate" in the context menu.
  • The annotator will suggest links to entities recognized in the image.
  • Example: create the project "Nepomuk" in the Nepomukshell, then annotate the following image. The annotator will suggest the term "Nepomuk".

Advanced search for expert users

  • The nepomuksearch protocol now supports SPARQL queries. SPARQL is a query language for submitting requests to the Nepomuk database. Example: the following query will return all items tagged with "semanticweb" or "p2p":
nepomuksearch:/?sparql=select ?r where {{?r nao:hasTag <nepomuk:/semanticweb>} UNION {?r nao:hasTag <nepomuk:/p2p>}} 

Troubleshooting and known issues

  • High CPU usage by /usr/bin/nepomukservicestub nepomukstorage: this can be caused by the volume of files being indexed by Strigi. Try to reduce the scope of the indexing by opening the KDE System Setttings, hitting "Desktop Search", "Advanced" and uncheck some folders. Restarting Nepomuk may be needed. Proceed as follow to do so:
 qdbus org.kde.NepomukServer /nepomukserver org.kde.NepomukServer.quit
nepomukserver 2> /tmp/nepomuk.stderr

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