Extension:JsonConfig/Tabular

This page describes JsonConfig's Tabular content support requested in T120452.

Tabular content is a machine-readable data similar to CSV and TSV formats. It allows any user to create a page, e.g. "Data:List of interesting facts.tabular" (demo), and keep it as a table, rather than wiki text. Tabular storage allows strings, numbers, booleans (true/false), and "localized strings" – strings that has different value depending on the language. Eventually, it would be good to also implement Q number support, allowing direct links to Wikidata.

Additionally, tabular data can store metadata, such as localized description and license. More metadata can be added as needed.

Tabular storage greatly simplifies storing data for lists, tables, and graphs. Graphs may directly access tabular data, and on-wiki tables and lists can be created by using simple Lua scripts. This storage is fundamentally different from Wikidata, because it works with "blobs" (batches) of data, whereas Wikidata works with tiny "facts". Wikidata technology is simply not suited for large storage such as the list of the most expensive paintings, the shoe size comparisons table, or data to plot Moscow subway growth graph.

After a long discussion, it seems Commons is the best fit for such data, and Commons community has overwhelming support for it. Commons community already has good experience with international multi-licensed content. Feel free to experiment with it at http://data.wmflabs.org/wiki/Data:Sample.tabular. Note that you can view it with different languages, e.g. http://data.wmflabs.org/wiki/Data:Sample.tabular?uselang=fr

Usage
All tabular data will be stored in the Data namespace on Commons, with a ".tabular" page title suffix, e.g. Data:My list.tabular The data will be accessible from all other wikis by: Unless a good reason is given, there will be no way to access data directly from wiki markup. Introducing a complex wikimarkup function to get a single cell's value seems overly complex and error prone, and should be done via Lua functions.
 * Should it be shorter, like .tab? Is it more readable/understandable by non-English speakers?)
 * will be able to use the data directly by using "wikitabular:///My list.tabular" graph protocol (no need for Data namespace)
 * Is wikitabular a good name? Alternatives: wikitabdata, wikitab, ...?
 * Should the page title have the page title's suffix?
 * Scribunto (Lua) modules via mw.data.getData( 'My list.tabular' ) function. The data will be returned as parsed JSON of the raw page content, so Lua module will be able to access all other metadata fields such as license and description. This function is not tabular-data specific. We might also want to introduce mw.data.getTabularData to get data with localized strings resolved for a specific language.

Example
This sample creates a table with 4 columns of 4 different types.

= Future Plans =
 * CSV and TSV copy/paste form to simplify transferring data to and from external spreadsheets.
 * An in-place spreadsheet table editor
 * Wikidata support, allowing direct links to localized Wikidata content

TBD / Questions

 * Licenses - how should the license be stored to make it machine readable and avoid untranslatable and unparsable free text
 * What metadata is needed? Current proposal has "license" (string) and "info" (localized string), but we might need more.
 * Cross-datacenter cache invalidation - JsonConfig supports remote cache invalidations, but it uses MW API call for that. What server should commons access to notify of data change?

Configuration
JsonConfig uses a very flexible (and a bit complicated) settings system. Both Commons wiki and all other wikis will need this code block to set up a cross-wiki shareable storage: Commons wiki will need to specify that data should be stored locally: Other wikis will need to set how to access remote data: