# SAW's LexFCS Endpoint with Solr

**URL:** <https://forum.clarin.eu/t/saws-lexfcs-endpoint-with-solr/1066>\
**Category:** General\
**Tags:** fcs\
**Created:** [4 November 2025 14:01 UTC](https://forum.clarin.eu/t/saws-lexfcs-endpoint-with-solr/1066 "2025-11-04T14:01:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![koerner](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.clarin.eu/koerner/32/80_2.png) [@koerner](https://forum.clarin.eu/u/koerner)\
**Post date:** [4 November 2025 14:01 UTC](https://forum.clarin.eu/t/saws-lexfcs-endpoint-with-solr/1066/1 "2025-11-04T14:01:38Z")

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The [Saxon Academy of Sciences and Humanities in Leipzig](https://www.saw-leipzig.de/en/) has released an easy to setup **LexFCS** endpoint implementation. The FCS endpoint is primarily for lexical resources described in the new [LexFCS Specification](https://doi.org/10.5281/zenodo.7849753) and intended to serve as reference implementation. It comes bundled with the [Apache Solr](https://solr.apache.org/) search engine to support search and retrieval of structured lexical data. The endpoint is ready for use in no time ([quickstart](https://github.com/saw-leipzig/lexfcs-endpoint/blob/main/README.md#quickstart) ⚡).

## Data format and query language

Lexical resources differ from standard text resources found in the [CLARIN Federated Content Search](https://www.clarin.eu/content/content-search) in that search and results are centered around lexical entries that are structured into various fields (lemma, pos, sentiment, …) with values and optional attributes (language, references). A custom query language **LexCQL** has been introduced to support querying this structure.

Apache Solr has been chosen for indexing this structured data by using nested documents with a generic field list. The FCS endpoint implementation will rewrite incoming LexCQL queries into complex Solr [Block Join Queries](https://solr.apache.org/guide/solr/latest/query-guide/block-join-query-parser.html) that enable search requests such as _lang = “deu” AND translation =/lang=eng “member of parliament”_ (search for german lexical entries that have a “translation” field with an English values of “member of parliament”). The Solr configuration may need some updates when handling non-latin languages due to different tokenization rules etc.

## Support your own lexical resources

The FCS endpoint implementation comes with a tiny example resource (based on the English Wiktionary) to easily test out the endpoint. [Adding new resources](https://github.com/saw-leipzig/lexfcs-endpoint/tree/main/lexfcs-solr#new-cores) is fairly straightforward but generally requires some kind of conversion into the [Solr data format](https://github.com/saw-leipzig/lexfcs-endpoint/tree/main/lexfcs-solr#data-format) used here.

Documentation and example configuration for custom deployments are available.

## Related

- [📜 Release LexFCS Specification v0.3](https://forum.clarin.eu/t/release-lexfcs-specification-v0-3/897) - forum post about LexFCS updates
- [LexFCS Endpoint (Source Code)](https://github.com/saw-leipzig/lexfcs-endpoint) - Solr searcher and FCS endpoint implementation
  - Documentation of Solr [data format](https://github.com/saw-leipzig/lexfcs-endpoint/tree/main/lexfcs-solr#data-format)
  - Documentation of [FCS Endpoint](https://github.com/saw-leipzig/lexfcs-endpoint/tree/main/lexfcs-solr-endpoint)
  - [Quickstart instructions](https://github.com/saw-leipzig/lexfcs-endpoint/blob/main/README.md#quickstart)

- [FCS Endpoint (live)](https://fcs.data.saw-leipzig.de/dict?x-fcs-endpoint-description=true&x-indent-response=2)

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<div class="post-metadata">

**Author:** ![koerner](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.clarin.eu/koerner/32/80_2.png) [@koerner](https://forum.clarin.eu/u/koerner)\
**Post date:** [4 February 2026 10:24 UTC](https://forum.clarin.eu/t/saws-lexfcs-endpoint-with-solr/1066/2 "2026-02-04T10:24:10Z")

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**:** 📣 **Update**

The source code [https://github.com/saw-leipzig/lexfcs-endpoint](https://github.com/saw-leipzig/lexfcs-endpoint) has been updated. The release **1.1.0** includes some fixes (LexCQL to Solr query translation, example data), various dependency updates as well as support for the new and upcoming `ExampleQuery` element for the Endpoint Description of the LexFCS Endpoint.

The update process should just be a `git pull` to update the source code _(There might be an issue with the example data? Under investigation.)_, and a rebuild and restart of the Endpoint Docker image `docker compose build` (depending on how it was deployed).