Скачать или смотреть DotNetRDF – How to Force CompressingTurtleWriter to Use QNames Instead of Full IRIs

Learn how to configure the `CompressingTurtleWriter` in DotNetRDF to output compact IRI formats (QNames) for more readable Turtle files.
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This video is based on the question https://stackoverflow.com/q/65002046/ asked by the user 'Katie' ( https://stackoverflow.com/u/14704757/ ) and on the answer https://stackoverflow.com/a/65003976/ provided by the user 'Kal' ( https://stackoverflow.com/u/1882789/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

When working with the DotNetRDF framework to export database content into Turtle files, developers often encounter the challenge of formatting their output. Specifically, many users want to control how identifiers (IRIs) are presented in the Turtle output. Instead of seeing cumbersome full IRIs like <http://sphn.ch/rdf/ontology/Swissmedi..., they prefer a more compact and readable format using QNames like medi:11275028.

In this guide, we will explore how to configure the CompressingTurtleWriter in the DotNetRDF framework to produce outputs in the desired format using QNames.

Understanding the Issue

In the scenario where a user has set up their namespaces correctly, they may export their graph using the CompressingTurtleWriter but end up with full IRIs in the output rather than the compact representation they sought. The expected output format is illustrated below:

[[See Video to Reveal this Text or Code Snippet]]

However, what users typically receive looks more like this:

[[See Video to Reveal this Text or Code Snippet]]

This inconsistency between expected and actual output can be frustrating and may lead to confusion when working with larger datasets.

Solution: Configuring the CompressingTurtleWriter

Step 1: Set Turtle Syntax

One way to obtain the desired output format is to adjust the Turtle syntax mode. The original Turtle specification didn't allow an identifier to begin with a digit, but the newer W3C version allows it. To ensure your output uses the W3C standard, set the syntax mode to TurtleSyntax.W3C.

Implementation Example

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Avoid "High-Speed Mode"

Interestingly, when the graph has a high ratio of unique subject nodes to triples (when (# unique subjects)/(# triples) 0.75), the writer enters a "high speed mode." In this mode, all forms of compression—including the use of QNames—are disabled.

To prevent this from happening, make sure to set the HighSpeedModePermitted property to false:

Implementation Example

[[See Video to Reveal this Text or Code Snippet]]

Complete Code Example

Putting everything together, here's how your implementation should look when exporting the graph to the Turtle file:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By properly configuring the CompressingTurtleWriter, you can achieve the desired output of using QNames instead of full IRIs in your Turtle files. The key steps include setting the Turtle syntax to W3C compliance and disabling high-speed mode if necessary. This not only enhances readability but also makes the data easier to work with.

Now that you know how to control the output format in DotNetRDF, you can streamline your development process and create cleaner Turtle files. Happy coding!