Virtuoso GeoSPARQL Support

May 1, 2026 · View on GitHub

Introduction

Release 7.2.6 marked the addition of GeoSPARQL function support to Virtuoso Open Source Edition, with additional enhancements in subsequent versions.

Besides a number of enhancements to the core Virtuoso engine, OpenLink added three plugins that extend Virtuoso's functionality:

proj4
geos
shapefileio

The proj4 and geos plugins can only be built against very specific versions of third-party libraries, which may not be available on every OS distribution, so you probably need to build them prior to building Virtuoso.

Package         Version         From
-------         -------         ---------------------------
proj            4.9.3           https://proj4.org
geo             3.5.1           https://www.osgeo.org/geos/

The new plugins are automatically added to the build process if the third-party libraries and header files are found when running the configure tool.

The following new options have been added:

$ ./configure --help
...
...
--enable-proj4(=DIR)    enable the proj4 plugin (default)
--disable-proj4         disable the proj4 plugin
--enable-geos(=DIR)     enable the geos plugin (default)
--disable-geos          disable the geos plugin
--enable-shapefileio(=DIR)
                        enable the shapefileio plugin (default)
--disable-shapefileio   disable the shapefileio plugin
...

OpenLink provides pre-built binary releases of Virtuoso Open Source Edition for a number of platforms including Linux, macOS and Windows.

New Plugins

The `proj4` Plugin

The proj4 plugin adds an interface between the Virtuoso engine and the PROJ library currently maintained by Frank Warmerdam et al.

This plugin adds support for transforming geospatial coordinates from one coordinate reference system (CRS) to another, including both cartographic projections and geodetic transformations.

The proj4 plugin currently requires v4.9.3 of the library, which can be downloaded here.

The PROJ library uses the following license:

All source, data files and other contents of the PROJ.4 package are
available under the following terms.  Note that the PROJ 4.3 and earlier
was "public domain" as is common with US government work, but apparently
this is not a well defined legal term in many countries.  I am placing
everything under the following MIT style license because I believe it is
effectively the same as public domain, allowing anyone to use the code as
they wish, including making proprietary derivatives.

Though I have put my own name as copyright holder, I don't mean to imply
I did the work.  Essentially all work was done by Gerald Evenden.

--------------

Copyright (c) 2000, Frank Warmerdam

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

The `geos` Plugin

The geos plugin adds an interface between the Virtuoso engine and the GEOS library currently maintained by the Open Source Geospatial Foundation.

According to their website:

GEOS (Geometry Engine - Open Source) is a C++ port of the Topology Suite (JTS). As such, it aims to contain the complete functionality of JTS in C++. This includes all the GIS Simple Features for SQL spatial predicate functions and spatial operators, as well as specific JTS enhanced topology functions.

This plugin adds support for GeoSPARQL functions to the Virtuoso engine.

The geos plugin currently requires v3.5.1 of the library which can be downloaded here.

The GEOS library is licensed under the terms of the GNU Lesser General Public License v2.1.

The `shapefileio` Plugin

The shapefileio plugin adds an interface between the Virtuoso engine and the Shapefile C Library currently maintained by Frank Warmerdam et al.

This plugin adds support for reading ESRI Shapefiles.

At this time, a version of this library is embedded in the Virtuoso codebase, so no external packages are required.

The shapefile library uses the following license:

LICENSE
The source for the Shapefile C Library is (c) 1998 Frank Warmerdam,
and released under the following conditions. The intent is that anyone
can do anything with the code, but that I do not assume any liability,
nor express any warranty for this code.  As of Shapelib 1.2.6 the
core portions of the library are made available under two possible
licenses. The licensee can choose to use the code under either the
Library GNU Public License (LGPL) described in COPYING or under the
following MIT style license. Any files in the Shapelib distribution
without explicit copyright license terms (such as this documentation,
the Makefile and so forth) should be considered to have the following
licensing terms. Some auxiliary portions of Shapelib, notably some of
the components in the contrib directory come under slightly different
license restrictions. Check the source files that you are actually using
for conditions.

DEFAULT LICENSE TERMS
Copyright (c) 1999, Frank Warmerdam
This software is available under the following "MIT Style" license, or
at the option of the licensee under the LGPL (see COPYING). This option
is discussed in more detail in shapelib.html.

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

SHAPELIB MODIFICATIONS
I am pleased to receive bug fixes, and improvements for Shapelib. Unless
the submissions indicate otherwise I will assume that changes submitted
to me remain under the above "dual license" terms. If changes are
made to the library with the intention that those changes should be
protected by the LGPL then I should be informed upon submission. Note
that I will not generally incorporate changes into the core of Shapelib
that are protected under the LGPL as this would effectively limit the
whole file and distribution to LGPL terms.

Opting for LGPL
For licensee's opting to use Shapelib under LGPL as opposed to the MIT
Style license above, and wishing to redistribute the software based
on Shapelib, I would ask that all "dual license" modules be updated to
indicate that only the LGPL (and not the MIT Style license) applies. This
action represents opting for the LGPL, and thereafter LGPL terms apply
to any redistribution and modification of the affected modules.

Changes to `virtuoso.ini`

After building and installing the new plugins, you may need to add them to the Plugins section of any existing virtuoso.ini file. Ensure each Load line uses a unique number, although numbering does not have to be sequential.

[Plugins]
...
...
Load20 = plain, proj4
Load21 = plain, geos
Load22 = plain, shapefileio

The proj4 plugin requires access to a number of data files from the proj project which are normally installed in /usr/share/proj. For this, you need to change your virtuoso.ini file and add this directory to the existing DirsAllowed setting, like this:

[Parameters]
..
..
DirsAllowed                     = ., /opt/virtuoso-opensource/vad, /usr/share/proj
..
..

After making these modifications to the virtuoso.ini file, you need to restart the virtuoso engine to make these additional functions available.

Troubleshooting

If the plugins are successfully built and installed, expect to see these lines in your virtuoso.log file:

12:08:51 { Loading plugin 8: Type `plain', file `proj4' in `/opt/virtuoso-opensource/hosting'
12:08:51   plain version 3230 from OpenLink Software
12:08:51   Cartographic Projections support based on Frank Warmerdam's proj4 library
12:08:51   SUCCESS plugin 8: loaded from /opt/virtuoso-opensource/hosting/proj4.so }
12:08:51 { Loading plugin 9: Type `plain', file `geos' in `/opt/virtuoso-opensource/hosting'
12:08:51   plain version 3230 from OpenLink Software
12:08:51   GEOS plugin based on Geometry Engine Open Source library from Open Source Geospatial Foundation
12:08:51   SUCCESS plugin 9: loaded from /opt/virtuoso-opensource/hosting/geos.so }
12:08:51 { Loading plugin 10: Type `plain', file `shapefileio' in `/opt/virtuoso-opensource/hosting'
12:08:51   ShapefileIO version 0.1virt71 from OpenLink Software
12:08:51   Shapefile support based on Frank Warmerdam's Shapelib
12:08:51   SUCCESS plugin 10: loaded from /opt/virtuoso-opensource/hosting/shapefileio.so }

If you see these lines near the bottom of your virtuoso.log file, then you need to install the proj-data package, if available for your operating system.

12:23:17 PL LOG: Initial setup of DB.DBA.SYS_PROJ4_SRIDS data from files in "/usr/share/proj"
12:23:17 PL LOG: Error during initial setup of DB.DBA.SYS_PROJ4_SRIDS data: 39000: FA005:
Can't open file '/usr/share/proj/epsg', error 2

If the proj plugin is initialized successfully, you see these lines near the bottom of your virtuoso.ini file:

12:10:08 PL LOG: Initial setup of DB.DBA.SYS_PROJ4_SRIDS data from files in "/usr/share/proj"
12:10:08 PL LOG: DB.DBA.SYS_PROJ4_SRIDS now contains 8650 spatial reference systems