SEMANTIC-VERSIONING.md

Semantic Versioning

When a new version of the Tilezen is released, developers should be able to tell from the version increment how much effort it will take them to integrate the new tiles with their map. We use semantic versioning to communicate this.

What is Semantic Versioning?

Semantic versioning (or SemVer) is a formalized way of making promises with an X.Y.Z version indicator.

Version components

• MAJOR.MINOR.PATCH, example: 1.0.0 (default)
• MAJOR.MINOR.PATCH-POSTFIX, example: 1.0.0-pre1 (optional)

Version parts:

1. MAJOR version X for incompatible API changes.
2. MINOR version Y when adding functionality in a backwards-compatible manner, and
3. PATCH version Z when fixing backwards-compatible bugs
4. pre-release version -POSTFIX when releasing developer previews

NOTE: The above applies after software has reached as version 1.0.0, no promises are made for earlier versions.

Developer level of effort:

• Major version X: high – significant integration challenges, read the changelog closely
• Minor version Y: low – some integration challenges, read the changelog
• Bug fixes Z: none – simply use the new tiles, skim or ignore the changelog
• Pre-release POSTFIX: low to high – some to significant integration challenges, read the changelog

Versioning the Tilezen API

Upon our version 1.0.0 release Tilezen makes the following promises:

Definition of terms

• common - These layers, propertys, and kinds are generally available across all features in a Tilezen response.
  • Establishes basic selection of features and their arrangement into specific named layers.
  • Core properties needed for display and labeling of features:
    • Special bits that make vector tile content interoperably Tilezen, including kind, kind_detail, landuse_kind, kind_tile_rank, min_zoom, max_zoom, is_landuse_aoi, sort_rank, boundary, and maritime_boundary.
    • Fundamental properties like name (including localized names), id, and source included on most every feature.
• common-optional - These are meant to be part of a common set, but may not be present because they aren't relevant or because we don't have the data (primarily feature propertys, but could also be layers).
  • Used to refine feature selection.
  • Lightly transformed interoperable Tilezen properties based on original data values. Examples include: country_capital, region_capital, bicycle_network, is_bridge, is_link, is_tunnel, is_bicycle_related, is_bus_route, walking_network, area, left & right names and localized name:* values on lines, and left & right id values on lines.
  • Fundamental properties like ref, colour, population, elevation, cuisine, operator, protect_class, and sport.
• optional - These are the properties of a specific, less important kind, or generally present across kinds but only in exceptional cases.
  • Often used to decorate features already selected for display.
  • Additional properties like capacity and covered.

MAJOR version increments:

1. Remove common layer
2. Change common layer name
3. Remove common-optional layer
4. Change common-optional layer name
5. Remove common feature property completely from all zooms
6. Change common feature property name
7. Remove common-optional feature property at zoom 14 or more
8. Change common-optional feature property name
9. Remove optional feature property at zoom 14 or more
10. Change kind value name
11. Remove kind value completely from all zooms
12. Move kind from one layer to another
13. Additional simplification across kind values in zooms 14, 15, or 16 (or max zoom) by removing common, common-optional, and/or optional properties by merging or other method
14. Simplification within kind values at zooms 16 (or max zoom) by removing common, common-optional, and optional properties by merging or other method
15. Change of <= -3 (earlier) to default min_zoom or max_zoom values to determine when kind is included
16. Change of >= +2 (later) to default min_zoom or max_zoom values to determine when kind is included

MINOR version increments:

1. Add common layer
2. Add common-optional layer
3. Add common feature property
4. Add common-optional feature property
5. Add optional feature property
6. Add new kind value
7. Additional simplification across kind values at zooms 13 or less by removing common, common-optional, and optional properties by merging or other method
8. Additional simplification within kind values at zooms 13, 14, or 15 by removing common, common-optional, and optional properties by merging or other method
9. Reassign 50% or more of existing kind value into a new kind value, when kind has 10,000 or more features
10. Change of <= -2 (earlier) to min_zoom or max_zoom values to determine when kind is included
11. Change of >= +1 (later) to default min_zoom or max_zoom values to determine when kind is included
12. Change the maximum Tilezen zoom (currently zoom 16).

PATCH version increments

1. Add optional layer
2. Change optional layer name
3. Remove optional layer
4. Additional simplification within kind values at zooms 12 or less by removing common, common-optional, and optional properties by merging or other method
5. Reassign an existing kind value to an another existing kind value when they are equivalent (e.g. fixing the spelling of a value coming from an upstream data source)
6. Reassign less than 50% of existing kind value into a new kind value, when kind has 10,000 or more features
7. Reassign more than 50% of existing kind value into a new kind value, when kind has less than 10,000 features
8. Change of -1 to default min_zoom or max_zoom values to determine when kind is included
9. Adjustments to the overall map balance (proportion of features in one layer or another, proportion of kinds in a single layer) by adjusting boosting of min_zoom values over the kind's default, limiting the number of individual kind features in a given tile coordinate, and other means.
10. Add unpublicized kind value
11. Remove unpublicized kind value
12. Correct a regression in the API (to the last good version)
13. Correct a newly added feature property name
14. Correct a newly added kind value

Versioning Data

We do not version data features, but we do attempt to indicate the data source and the feature ID as assigned by that source so customers can investigate upstream changes.

Frequency of data updates

Tilezen has 4 primary sources:

• Natural Earth (used for zooms 0-8 for most everything) updates infrequently (often annually)
• OpenStreetMap (used for zooms 9+ for most everything, sometimes earlier) updates frequently (at least daily)
• OpenStreetMapData (used for zooms 9+ in the earth and water layers only) updates infrequently (optimistically monthly)
• Who’s On First (used for zooms 12+ for places layer) updates frequently (at least daily)

INDIVIDUAL FEATURES are not versioned

Examples:

1. Add new feature
2. Removal of existing feature
3. Change feature name
4. Change feature geometry
5. Change feature property values (including property removal if removed from original source)
6. Change feature kind value (when upstream data source reclassifies them).
7. Change feature min_zoom &/or max_zoom values (when area or other signal changes upstream).

NOTE: It is possible to query the version of individual features by looking at a feature's source and id properties and performing a lookup via the source service, but that is beyond the scope of Tilezen. Because of simplification, id properties are not always available due to feature merging.

LANGUAGES are not versioned

In addition to the common name locals call a place, the following common and common-optional languages are generally available:

Common languages:

1. name:ar العربية (Arabic) – common
2. name:bn বাংলা (Bengali) – common-optional
3. name:de Deutsch (German) – common-optional
4. name:en English – common
5. name:es español (Spanish) – common
6. name:fr français (French) – common
7. name:gr ελληνικά (Greek) – common-optional
8. name:hi हिन्दी (Hindi) – common-optional
9. name:id Bahasa Indonesia (Indonesian) – common-optional
10. name:it italiano (Italian) – common-optional
11. name:ja 日本語 (Japanese) – common-optional
12. name:ko 한국어 (Korean) – common-optional
13. name:nl Nederlands (Dutch) – common-optional
14. name:pl Polski (Polish) – common-optional
15. name:pt Português (Portuguese) – common-optional
16. name:ru Русский (Russian) – common
17. name:sv Svenska (Swedish) – common-optional
18. name:tr Türkçe (Turkish) – common-optional
19. name:vi Tiếng Việt (Vietnamese) – common-optional
20. name:zh 中文 (Chinese): primarily simplified but sometimes traditional – common

Arabic, Chinese, English, French, Russian and Spanish are used by the United Nations for meetings and official documents. The other languages listed are either proposed as official language of the United Nations (Bengali, Hindi, Portugese, and Turkish) or frequently used in OpenStreetMap, Who's On First, or Wikipedia.

Additional localized names are available as common-optional and optional, but their actual use is the data is not widespread.

POLITICAL GEOGRAPHY is not versioned

Examples:

1. Major additions, deletions to country names, borders, disputed territories, and capitals are possible and may be advertised but do not bump the Tilezen API version.
2. Minor corrections to country names, borders, disputed territories, capitals, and other administrative geography are always possible and will not be tracked or advertised.

Versioning the Tilezen Service

MAJOR version increments:

1. Rollup of MAJOR Tilezen API changes
2. Change the maximum Tilezen zoom at which tiles are generated by default (currently zoom 16)
3. Remove a file format
4. Backwards incompatible change to a file format
5. Tilezen software dependency has a breaking change to the tile response

MINOR version increments:

1. Rollup of MINOR Tilezen API changes
2. Add a file format

PATCH version increments:

1. Rollup of PATCH Tilezen API changes
2. Infrequent update of static data sources like Natural Earth or OpenStreetMapData
3. Backwards compatible change to a file format
4. Software dependency has a backwards compatible change or bug fix with no change to the tile response

See also

• VERSION
• http://semver.org
• https://github.com/nvkelso/natural-earth-vector/blob/master/README.md
• https://github.com/whosonfirst/whosonfirst-placetypes#roles