Write data to a shidashi stream binary file

Serializes data together with a JSON header into the binary envelope expected by the JavaScript window.shidashi.fetchStreamData(id) method.

Usage

stream_to_js(
  abspath,
  data,
  type = c("raw", "json", "int32", "float32", "float64"),
  ...
)

abspath: Character scalar. Absolute path to the target .bin file. Use stream_path(id) to obtain a path under the app's www/stream/ directory.
data: The data to serialize. See Details for how each type interprets this argument.
type: Character scalar. One of "raw", "json", "int32", "float32", or "float64".
...: Additional named scalar values to embed in the JSON header and expose to the JavaScript caller via result.header.

Invisibly returns abspath.

Wire format


  [endianFlag: 1 byte]  [headerLen: uint32 LE]  [header: UTF-8 JSON]  [body]

endianFlag is always 0x01 (little-endian). header is a JSON object containing at minimum data_type plus any extra fields passed via ....

Body encoding by type

"raw": Passed through verbatim; data must be a raw vector or will be coerced via as.raw().
"json": data is serialized with jsonlite::toJSON(auto_unbox = TRUE).
"int32": data is coerced to integer and written as 4-byte little-endian signed integers.
"float32": data is coerced to double and written as 4-byte little-endian IEEE 754 single-precision floats.
"float64": data is coerced to double and written as 8-byte little-endian IEEE 754 double-precision floats.