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Last updated: 24 Sep 2018

collections-publisher: Decision record: Defer Merging of Taxonomy Apps

Created: 2016-02-03


Team Finding Things is currently working on a new taxonomical structure for content on GOVUK, in order to make it easier for users to find relevant information. Broadly speaking, this involves three distinct, parallel streams of work -

  • defining the taxonomy itself.
  • designing a tagging interface to easily assign content to an appropriate taxonomical category.
  • code/architectural changes to support the above in the context of the V2 publishing API.

At present, we have three taxonomical structures on GOVUK:

Creation of these structures is handled entirely in the collections-publisher application. This app also includes functionality to curate/group these structures, i.e. - setting certain topics as subtopics, or assigning one taxon as the parent of another.

The taxonomy definition work is underway, and we've recently introduced functionality to make the resulting taxon data available via API calls to the content store. This is so that our designers have access to useful test data in their interface prototyping work. Enabling this involved introducing a 'taxon' content type. We decided to place the creation/editing interface for this content type in collections-publisher, because of the conceptual similarity to topics and browse pages.

In addition (and earlier on, before taxons became a type of content on GOVUK), architectural changes to support the V2 publishing API and its associated publishing pipeline prompted the creation of the content-tagger app. This is intended to be a single interface through which all content on GOVUK can be tagged. It currently supports tagging with mainstream browse pages, topics, and organisations. We will inevitably need to tag content to specific taxons, so content-tagger will soon be updated to provide this functionality as well.

The structure and responsibilities of these two apps were established quickly with minimal communication across the team. An architectural discussion was held on 2016-02-02 to clarify their roles and to decide whether or not to merge or move functionality. This latter question was raised due to some confusion around the presence of taxonomy-related code in two different apps. This was exacerbated by the fact that bulk-creation of taxons and the mapping of these to content items is a piece of functionality that currently exists as a set of scripts sitting solely in content-tagger.


We've decided to defer merging these applications or making any move to isolate taxonomy-specific functionality into a single, distinct app.

The new taxonomical structure will eventually supersede both mainstream browse pages and topics as a means of navigating and discovering content. When that happens, there may be value (simplicity, ease of maintenance) in having a single app which allows creation of taxons, creation of hierarchies made up of these taxons, and tagging of content to taxons. Merging the apps now is a non-trivial undertaking and the benefits of doing so don't outweigh the time investment. This is particularly the case given the higher priority pieces of work we have planned in the near future - migrating all apps across GOVUK to conform to the new publishing/tagging architecture, and deciding how to implement a shared, uniform tagging UI in both content-tagger and the publishing apps.


Accepted, 2016-02-03.


  • Taxon creation/editing will be handled by collections-publisher, while tagging of content to specific taxons will be handled by content-tagger.
  • With taxon creation/editing staying in collections-publisher, it's arguable that the app has evolved to a point where its name is no longer particularly indicative of what it does. This is a source of confusion for anyone attempting to understand how the app fits into GOVUK's architecture. A renaming may well be required in the not-too-distant future.