Crate archiver 

A client for the EPICS Archiver Appliance retrieval API.

The pieces are split so that a browser build could reuse everything but the HTTP: ArchiverClient builds the request URLs (*_url), the parse_* functions decode the bodies, and the blocking get_data/search/metadata methods do both over ureq on native targets. In a browser those methods fail at once.

Times are UTC seconds since the Unix epoch as f64 (sub-microsecond resolution for current dates), the same as bobview’s trend and archiveview’s plot.

See DESIGN.md at the repository root for the wire format and its surprises (bare NaN tokens, string PREC, [ ] for no data, binned [mean, std, min, max, count] values from optimized_N).

Structs

ArchiverClient

An Archiver Appliance retrieval service. Cheap to clone; holds no connection state, so it can be shared freely between threads and between several plots.

Meta

The meta object of a response, with the common fields decoded. Values may arrive as strings or numbers; both are accepted.

PvInfo

What getMetadata says about a PV (all optional: servers differ).

Query

A getData.json request.

Sample

One plotted point of archived data.

Search

A getMatchingPVs request.

TimeSeries

One PV’s archived data for a request.

Enums

Error

Why a request failed.

Operator

Server-side processing for a data request.

SearchMode

How a search pattern is matched.

Severity

An archived alarm severity (the severity field: 0..=3).

ValueKind

What the archived values were, as seen in the response.

Constants

DEFAULT_SEARCH_LIMIT

The default number of PV names a search asks for.

MAX_BINS

The most bins an optimized_N request asks for, whatever the plot width.

Functions

format_time

t (UTC epoch seconds) as YYYY-MM-DDTHH:MM:SS.mmmZ, rounded to the millisecond. Non-finite or out-of-range times are clamped to the epoch and to year 9999.

parse_data

Decode a getData.json body: one TimeSeries per PV, empty for [ ]. Tolerates bare NaN/Infinity/-Infinity, string or numeric PREC/LOPR/HOPR, unknown keys, and fields objects. A severity-3 sample whose fields hold cnxlostepsecs becomes a Sample::gap. A 5-element array val on a scalar PV is an optimized bin (binned = true); other arrays are waveforms (val holds element 0).

parse_metadata

Decode a getMetadata body.

parse_names

Decode a JSON array of PV names (getMatchingPVs, getAllPVs).

parse_time

An archiver timestamp (Instant.parse / ISO offset forms, e.g. 2024-01-02T03:04:05.123Z or 2024-01-02T03:04:05-07:00) as epoch seconds.

parse_version

Decode a getVersion body: {"version": "..."}.

regex_escape

text with every regex metacharacter backslash-escaped, so it matches itself (in Java’s regex syntax, which the appliance uses, and in Rust’s).

sanitize_json

Replace the bare tokens NaN, Infinity and -Infinity outside strings with null, so serde_json accepts the body. Borrowed when there are none.

Type Aliases

Result