Robert Isele (brox GmbH)
Anja Jentzsch (Hasso Plattner Institut)
Christian Bizer (University of Mannheim)
Julius Volz (Google)
Petar Petrovski (University of Mannheim)

The Silk framework is a tool for discovering relationships between data items within different Linked Data sources.
Data publishers can use Silk to set RDF links from their data sources to other data sources on the Web.



  1. About Silk
  2. Silk Workbench
  3. Silk Command Line
  4. Silk Free Text Preprocessor
  5. Support
  6. Download
  7. Version History
  8. Acknowledgments
  9. References

About Silk

The Web of Data is built upon two simple ideas: First, to employ the RDF data model to publish structured data on the Web. Second, to set explicit RDF links between data items within different data sources. Background information about the Web of Data is found at the wiki pages of the W3C Linking Open Data community effort, in the overview article Linked Data - The Story So Far and in the tutorial on How to publish Linked Data on the Web.

The Silk Link Discovery Framework supports data publishers in accomplishing the second task. Using the declarative Silk - Link Specification Language (Silk-LSL), developers can specify which types of RDF links should be discovered between data sources as well as which conditions data items must fulfill in order to be interlinked. These link conditions may combine various similarity metrics and can take the graph around a data item into account, which is addressed using an RDF path language. Silk accesses the data sources that should be interlinked via the SPARQL protocol and can thus be used against local as well as remote SPARQL endpoints.

Silk can be used through the Silk Workbench graphical user interface or from the command line. Both variants are based on the Silk Link Discovery Engine which offers the following features:

Silk Workbench

Silk Workbench is a web application which guides the user through the process of interlinking different data sources.

Silk Workbench offers the following features:

Documentation of the Silk Workbench is available in the Wiki.

Silk Command Line Applications

In addition to the Workbench, Silk provides three different command line applications for executing link specifications:

Documentation of all three command line applications is available in the Wiki.

Silk Free Text Preprocessor

The main goal of the Free Text Pre-processing tool is to produce a structured representation of data that contains or is derived from free text. The tool takes as input an RDF file with properties with free text values and an additional RDF file that contains structured data used to learn the extraction model. Based on the learned model the tool extracts new property-value pairs from free text. The resulting output is an RDF dump file containing the extracted structured values. Using a declarative XML-based language, a user can specify which extraction methods to use.

Documentation of the Silk Free Text Preprocessor is available in the Wiki.


Documentation on the Silk Link Discovery Framework is available in the Wiki.

For questions and feedback please use the Silk Google Group.


All stable releases can be downloaded. The framework can be used under the terms of the Apache Software License.

The latest source code is available from the project's Git repository and can be browsed online.

Version History

Version Comment Release Date
2.6.0 New Version of the Workbench
Plugin System
Silk Free Text Preprocessor
2.5.3 Various improvements and bugfixes. 2012-03-06
2.5.2 Adding active learning of linkage rules. 2011-11-17
2.5.1 Various improvements to the Workbench. 2011-10-21
2.5 Added support for learning linkage rules. 2011-10-03
2.4.2 SPARQL/Update output
Dump file input
Improved indexing
Many improvements to the Silk Workbench
2.4.1 Introduces per-comparison thresholds.
New data transformations and distance measures including token-based distance measures.
Improved Silk Workbench.
2.4 Added the new Silk Workbench, a web application which guides the user through the process of interlinking different data sources.
2.3 Improved loading perfomance: Multiple parallel SPARQL queries are executed, while their results are merged on the fly.
Improved matching performance: New blocking method offers greatly improved performance.
Improved overall performance: Matching tasks are now executed concurrently to loading data instead of waiting for the complete data set to be loaded.
2.2 Added Silk MapReduce 2010-10-06
2.1 Added Silk Server
Added a geographical distance metric by Konrad Höffner (MOLE subgroup of Research Group AKSW, University of Leipzig)
2.0 Reimplementation of the Silk framework in Scala.
Improved scalability and performance.
Prematching replaced by a more transparent blocking.
Configuration is checked for consistency prior to link generation.
Support of the OAEI Alignment format.
(Anja and Robert)
0.2 Added prematching of data items (Julius).
The Silk 0.2 language specification is still available and Silk 0.2 framework can be downloaded from GoogleCode.
0.1 Initial Release of the Python version of the Silk framework (Julius and Chris) 2009-02-01


This work was supported in part by Vulcan Inc. as part of its Project Halo and by the EU FP7 project LOD2 - Creating Knowledge out of Interlinked Data (Grant No. 257943).