bricklayer_fetch: Fetch a URL to disk with an Internet Archive fallback...

In rmoriebricklayer: Reproducible Data Capsules with Provenance and Fallback

Fetch a URL to disk with an Internet Archive fallback (C++/libcurl)

Description

The shared data-fetch foundation of the morie ecosystem. Downloads url to dest; if the live download fails (404, network), it retries the Wayback Machine snapshot – so a rotated or removed source file (CIHI, open-data portals) stays retrievable. Backed by the package's C++ rmbl_fetch_with_fallback kernel (libcurl), which rmorie and morie share through LinkingTo.

Usage

bricklayer_fetch(url, dest, wayback = "", timeout = 120L)

Arguments

url	Live source URL.
dest	Destination file path.
wayback	Optional explicit Wayback snapshot URL. "" (default) auto-resolves one via wayback_snapshot_url.
timeout	Per-request timeout, seconds.

Value

Invisibly, one of "live", "wayback", or throws on total failure.

Examples

# Inputs are validated before any network access:
try(bricklayer_fetch("", tempfile()))          # empty url -> error


# Downloads from the live web service; try() keeps the example graceful
# when neither the live URL nor its Wayback fallback is reachable.
dst <- tempfile(fileext = ".xlsx")

# Live download; auto-resolves a Wayback snapshot only if the live URL fails.
try(bricklayer_fetch(
  "https://www.cihi.ca/sites/default/files/document/hospital-beds-2024-2025-data-tables-en.xlsx",
  dst))

# Pin an explicit Wayback snapshot to fall back to, and a shorter timeout.
try(bricklayer_fetch(
  "https://example.org/rotated-file.csv", tempfile(fileext = ".csv"),
  wayback = "https://web.archive.org/web/2024id_/https://example.org/rotated-file.csv",
  timeout = 60))

# The return value tells you which source served the file.
status <- try(bricklayer_fetch("https://cloud.r-project.org/", tempfile()))
status   # "live" or "wayback"

rmoriebricklayer documentation built on Aug. 5, 2026, 9:08 a.m.