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Add RFC 108 text: driver removals for GDAL 3.11 (OSGeo#11862)
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doc/source/development/rfc/rfc108_driver_removal_3_11.rst
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| .. _rfc-108: | ||
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| ===================================================================== | ||
| RFC 108: Driver removals for GDAL 3.11 | ||
| ===================================================================== | ||
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| ============== ============================================= | ||
| Author: Even Rouault | ||
| Contact: even.rouault @ spatialys.com | ||
| Started: 2025-02-18 | ||
| Status: Adopted, implemented | ||
| Target: GDAL 3.11 | ||
| ============== ============================================= | ||
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| Summary | ||
| ------- | ||
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| This RFC communicates about the partial or total removal of obsolete drivers | ||
| for GDAL 3.11. | ||
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| Motivation | ||
| ---------- | ||
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| GDAL is an ever growing code base, with probably more than 50% of the code | ||
| base being used by less of 1% of users. This is isn't very sustainable, and quite | ||
| demotivating for current maintainers who know nothing/little about most drivers, | ||
| have no evidence that they are used, and regularly stumble upon them when doing | ||
| whole codebase enhancements. | ||
| The decision of which driver to removal comes from a mix of "intuition" and | ||
| community feedback from | ||
| https://docs.google.com/spreadsheets/d/12yk0p8rRK4rAYO_VwXboatWkiILAjE2Cepu32lsHhM8/edit?gid=0#gid=0 | ||
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| Technical solution | ||
| ------------------ | ||
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| Fully removed drivers: | ||
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| - raster: | ||
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| * JP2Lura: JPEG2000-capable driver. Was based on a proprietary SDK. | ||
| Initial proponents of that driver no longer use it. | ||
| * OZI OZF2/OZFX3: OZI now uses a new format v4 that has not been | ||
| reverse engineered. | ||
| * BLX (Magellan BLX Topo File Format). No activity in this driver from | ||
| non-GDAL team. No obvious sign in issue tracker it is used. | ||
| * XPM driver: Not relevant in a geospatial context. Obsolete image format. | ||
| Users can probably use ImageMagick if support for it is needed. | ||
| * SGI driver: same as above | ||
| * FIT driver: No idea what it is about (not to be confused by FITS, which | ||
| is actively used by astronomic/planetary community) | ||
| * DIPEx: No idea what it is about | ||
| * CTable2 driver: obsolete PROJ.4 grid format. There was just one file ("null") | ||
| known to use that format. | ||
| * R (R Object Data Store (``*.rda``)): not known to be used. Not to be confused with | ||
| the RRaster driver which is used in the R ecosystem. | ||
| * GSAG (Golden Software ASCII) and GSBG (Golden Software 6.0 binary): likely | ||
| obsolete. GS7B (Golden Software 7.0 binary) kept as there are signs it is | ||
| used. | ||
| * Rasterlite: Rasterlite 1.0 format. Obsolete/no longer maintained by the | ||
| Spatialite crew. The SQLite driver has support for Rasterlite 2 | ||
| * BT (VTP .bt Binary Terrain Format). The VTP project seems abandoned since | ||
| 2015. | ||
| * SDTS: obsolete | ||
| * RDB (RIEGL Laser Measurement Systems GmbH): Not CI tested. Depends on | ||
| proprietary SDK. Removed with agreement from RIEGL. | ||
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| - vector: | ||
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| * Geoconcept export .txt: no sign it is used. Feedback from a French GIS | ||
| forum when asking if someone still uses the driver: "It is not clear who still | ||
| uses Geoconcept (the software) at all" | ||
| * OGDI: Vector Product Format / DGN / VMap. All obsolete formats. The | ||
| problematic part is that it depends on libogdi, which is an obsolete C | ||
| code base nobody sane would want to maintain anymore. | ||
| * SDTS: obsolete | ||
| * SVG: only supported files from Cloudmade Vector Stream Server, which no | ||
| longer exists. The code could probably be re-enabled to be made more generic | ||
| and handle arbitrary SVG, if the needs arises. | ||
| * Tiger: pre-2006 format for US Census. New datasets are in shapefile. | ||
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| Write-support removal: | ||
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| - raster: | ||
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| * ADRG: defense-related format. Write support was mostly to test | ||
| the read side of the driver | ||
| * ELAS: not sure what it is about and that this is actively used | ||
| * PAux: not sure what it is about and that this is actively used | ||
| * MFF: not sure what it is about and that this is actively used | ||
| * MFF2/HKV: not sure what it is about and that this is actively used | ||
| * LAN: old ERDAS format before HFA (.img). "raw format", does not support compression. Write support doesn't seem useful. | ||
| * BYN: Canadian grid-related format. Write support doesn't seem useful | ||
| * NTv2: read-support definitely useful. Write support obsolete since PROJ 7 | ||
| and use of Geodetic TIFF Grid format. | ||
| * USGSDEM: obsolete format. There might be historic datasets to read, but | ||
| write support doesn't seem useful | ||
| * ISIS2: Planetary format. Obsoleted by ISIS3. ISIS2 write support not used | ||
| by USGS. | ||
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| About/only 50,000 lines of code removed. | ||
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| Discussion | ||
| ---------- | ||
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| - Q. Are we sure they are not used? | ||
| A. No, we aren't. We could also have used a more progressive deprecation | ||
| mechanism (like requiring a runtime configuration option to be set), but we | ||
| don't think it is worth the extra burden. Let's see if we get massive complaints | ||
| from users, and use git revert if needed. We add a similar phase around GDAL 3.5 | ||
| and as far as I remember, we just got a couple of remarks, but did not end up | ||
| reviving deleted drivers. | ||
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| - Q. Would a dedicated per-driver maintainer model help? | ||
| A. Maybe, although in most of the above cases, most of those drivers are not | ||
| problematic per-se. They are just sitting there, contributing to the | ||
| overall weight of the library, and occasionally getting into our legs. | ||
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| - Q: I don't see the logic in the above removals. That seems a bit random at times. | ||
| A. Yes, it is. Like cognitive processes are sometimes. This is also a way | ||
| to scare people contributing drivers to GDAL that we might scrap them when | ||
| that becomes inconvenient. | ||
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| - Q. GDAL is all about support for odd formats! Don't do this! | ||
| A. Feel free to create a gdal-legacy-drivers project. | ||
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| - Should we consider in the future adding telemetry in GDAL? | ||
| Have looked at https://opentelemetry.io a bit. Seems a bit impressive... | ||
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| Documentation | ||
| ------------- | ||
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| Removed drivers will be mentioned at bottom of https://gdal.org/en/latest/drivers/raster/index.html | ||
| and https://gdal.org/en/latest/drivers/vector/index.html with the mention of | ||
| the version where they have been removed. This gives a way for users that would | ||
| need them to use the appropriate past version(s). | ||
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| Related issues and PRs | ||
| ---------------------- | ||
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| * Candidate implementation: https://github.com/OSGeo/gdal/pull/11758 | ||
| (JP2Lura and OZI have already been removed in master) | ||
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| Funding | ||
| ------- | ||
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| Funded by GDAL Sponsorship Program (GSP) (this RFC text) | ||
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| Voting history | ||
| -------------- | ||
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| +1 from PSC members JukkaR, JavierJS, KurtS, HowardB, DanielM, and -0 from DanB. | ||
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| .. below is an allow-list for spelling checker. | ||
| .. spelling:word-list:: | ||
| rda | ||
| VMap | ||
| libogdi | ||
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