[postgis-devel] A letter to the Postgis Developers and Packagers

[Andrea Peri]

Hello to all Postgis Developers and Packagers,

Tuscany Region is investing in several GFLOSS systems and right
now is building the Spatialite ISO topology interface consistent
with the one already funded for PostGIS.

It then commissioned to Sandro Santilli (strk) and Sandro Furieri
(the developer of the Spatialite system) the development of a
C language API implementing the same functions of the PostGIS
Topology module. The goal of this library was to be usable with both
spatialite and postgis, thus ensuring all the necessary compatibility.

We thought it was a good idea to insert this new API in the
liblwgeom library (after having a positive opinion by Santilli about
the utility for PostGIS of this operation) so to replace the
plpgsql topology code in PostGIS (also completed with the fundings
of Tuscany Region) with C code using the new liblwgeom-topo API.

We thought that the substitution of the PostGIS Topology functions from
plpgsql in C would not cause any problems to users, offering
instead performance improvements. But during its testing in Spatialite,
we realized that the library required several further refirements in its API.

This has created a situation of embarrassment that caused the break
of the new liblwgeom API just in the same day it was released along
with the new 2.2.0 version of PostGIS.

We apologize for causing, with our interventions in liblwgeom, the
release within PostGIS of a topological library that is not yet complete
and which definitely needs several revisions and other changes to the API.

So we've tried to find a quick fix to solve the problem we caused,
trying to avoid further inconveniences in the process of maintenance and
release of PostGIS.

Beeing in need of a more rapid test and release cycle for the topology
library, and with the aim to create a library which is compatible with
both PostGIS and Spatialite, we have identified as the best solution
to carry out the development, test and release activities in a separate
project. This choice also allows us to write the library with a thread-safe
model, which is not needed by PostGIS.

As we fear the liblwgeom-topo code might be too immature and prone
to API breakage, we offer to finance the recovery in PostGIS of the
previous plpgsql implementation of the Topology module.

The new topological library of Tuscany Region will be deposited on a
distinct GIT repository, with an open license similar to that of
liblwgeom and of course we will be pleased and honored if in the future,
when it will be more robust and reliable, the Community of PostGIS
Developers and Packagers will decide to link it as a shared library for the
topological component functions.

With cordiality, Andrea Peri


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Andrea Peri
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qwerty àèìòù
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