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FoLiA Document Server

The FoLiA Document Server is a backend HTTP service to interact with documents in the FoLiA format, a rich XML-based format for linguistic annotation ( It provides an interface to efficiently edit FoLiA documents through the FoLiA Query Language (FQL). However, it is not designed as a multi-document search tool.

The FoLiA Document server is used by FLAT (

The FoLiA Document Server is written in Python 3, using the FoLiA library in pynlpl and cherrypy.


The FoLiA Document Server consists of a document store that groups documents into namespaces, a namespace can correspond for instance to a user ID or a project.

Documents are automatically loaded and unloaded as they are requested and expire. Loaded documents are kept in memory fully to facilitate rapid access and are serialised back to XML files on disk when unloaded.

The document server is a webservice that receives requests over HTTP. Requests interacting with a FoLiA document consist of statements in FoLiA Query Language (FQL). For some uses the Corpus Query Language (CQL) is also supported. Responses are FoLiA XML or parsed into JSON (may contain HTML excerpts too), as requested in the FQL queries themselves.


  • webservice
  • queries using FQL, or alternatively CQL (limited)
  • multiple return formats (FoLiA XML, JSON, FLAT)
  • versioning control support using git
  • full support for corrections, alternatives!
  • support for concurrency

Note that this webservice is NOT intended to be publicly exposed, but rather to be used as a back-end by another system. The document server does support constraining namespaces to certain session ids, constraining FQL queries to not violate their namespace, and constraining uploads by session id or namespace. This is secure for public exposure only when explicitly enabled and used over HTTPS.

If you are looking for a command line tool that interprets FQL/CQL and queries FoLiA documents, use the foliaquery tool from the FoLiA-tools package rather than this document server, see