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Commons Merged

Commons Merged is a merged database built from multiple data packages—i.e., data objects in a repository, as released with a version identifier) on the Federal LCA Commons. The database is assembled by the LCA Data Package Manager (LDPM), which follows the original authors’ instructions for connecting processes via exchange.defaultProvider pointers across data packages.

Why Commons Merged?

Previously, when a user wanted to integrate an FLCAC data package into their local openLCA database, they had to individually download and import each package then manually link objects across them. This prior workflow emerged as a work-around to an openLCA Collaboration Server limitation: it cannot preserve UUID pointers (Refs) across packages (e.g., a process from package X intends to consume the output reference flow of another process from package Y).

Instead, Commons Merged offers users a single download with cross-package links already established, wherein all exchange.amount and .unit values are carefully preserved during the linking procedure. Furthermore the build routine (and linking subroutine) is deterministic: a unique manifest.toml input will yield a consistent, reproducible output[1].

Details

Within Commons Merged, individual processes are labeled with process.tags to denote their parent data package. Cross-package connections are based on two sets of instructions:

  1. The “defaultProvider.@id” JSON component of an exchange.description (example here) value embedded on each bridge process input

{"comment": "", "defaultProvider.@id": "22e58fa0-fd94-4b4a-9f65-bf9f5204defc"}

  1. Supplemental links established via the LDPM’s provider_links.yaml configuration file.

Despite their central role in supporting the pre-Commons Merged workflow, bridge processes have been preserved as containers for explicit declarations of cross-package connections (i.e., much like how import statements work in Python).

Furthermore, aside from serving as a tool to repeatedly mint Commons Merged and Commons Merged Hybrid, the LDPM can also be used to build custom LCA databases using any desired combination of data packages and release versions available on the FLCAC.

Releases

The pair of Commons Merged builds made available on the FLCAC are listed below with their respective dependencies. For the most up-to-date information, please refer to each database’s description as hosted on the Commons.

  1. Commons Merged

  1. Commons Merged Hybrid (with USEEIO)

Footnotes

  1. Just like software package managers, wildcard specifiers like “*” (i.e., to use a depedency’s latest version) must replaced by fixed version numbers to produce a consistent “frozen” build; otherwise the build will steadily change as new versions are released.

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