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Read-only HTTP-served Zarr v3 store.

Source: R/http_store.R
HttpStore.Rd

Implements the ZarrStore interface over HTTP(S). Used by zarr_daf() when given an http(s):// URL pointing at a .daf.zarr directory served by a static web server. Reads the Zarr v3 inline consolidated metadata from the root zarr.json once at open: v3 stores carry consolidated_metadata.metadata (a dict keyed by node path) in the root group instead of the v2 .zmetadata file. Subsequent store_exists and store_list resolve against that index, node zarr.json reads are served from it (re-serialized to the bytes the reader would otherwise have fetched per node), and chunk fetches are cached in process memory.

Usage

HttpStore(
  url = character(0),
  index = list(),
  chunk_cache = new.env(parent = emptyenv())
)

Arguments

url

Root URL of the served Zarr v3 directory.

index

Named list: the v3 node metadata index parsed from the root zarr.json consolidated_metadata.metadata (keyed by node path, with no /zarr.json suffix).

chunk_cache

Environment caching fetched chunk bytes (and the root zarr.json) by path.

Details

Writes hard-error: HTTP-served Zarr is read-only.

Zarr version: this backend targets the Zarr v3 on-disk layout that dafr reads and writes locally (DataAxesFormats.jl 0.3.0). A legacy v2 store (root .zmetadata, no root zarr.json) is rejected on open with a python -m zarr v2_to_v3 conversion hint, mirroring the local DirStore / MmapZipStore v2 rejection. Note this is distinct from http_daf() (the FilesFormat-over-HTTP path in http_daf()), which uses metadata.zip and is unaffected.