Export JSON Schema

Export the effective constraints of one Property value, Action input or output, Event output or Context definition for use with JSON Schema tools.

esdieff schema --document examples/thermostat-check/rich.sdf.json \
  --kind action_input --pointer /sdfObject/Thermostat/sdfAction/configure \
  examples/thermostat-check/rich.sdf.json

The default output is an esdieff.schema/1 JSON report. It identifies the selected document, kind and definition pointer, supplied source attempts, dialect, fidelity and first refusal reason. A successful report contains a schema object. A refusal contains schema: null and exits with status 3. Invalid requests exit with status 2. Failed host output uses status 4, as with other commands.

Use --format schema to write only the standalone schema to stdout. On refusal this mode writes the reason to stderr, exits with status 3 and writes nothing to stdout. Shell redirection may still create an empty file, so check the exit status before using the file.

Select property, action_input, action_output, event_output or context. Action and Event pointers name the affordance, as in Sample-value checking. Context pointers name the Context definition itself. Supply dependencies as additional explicit inputs. Export never downloads dependencies. One input may be - for stdin. Use -- before paths starting with a hyphen.

Fidelity

The dialect is JSON Schema Draft 2020-12. Successful fidelity is json-values. This means the supported effective constraints describe ordinary JSON values using the mappings below. It does not establish whole-model validity, a protocol payload binding, satisfiability or generated-code correctness. Model acquisition and reference composition reuse the normal catalogue. The report records whether composition relied on the copied-reference relocation interpretation.

Nullable defaults to true for ordinary Full data descriptions. It widens type admission only. Const and enum constraints still apply to null. An optional map entry is separate from an entry whose value can be null. Repeated SDF required names become one JSON Schema required name. Choice alternatives can overlap, so oneOf would be incorrect.

Property read/write/observe characteristics, declaration requiredness and enclosed reusable data definitions do not constrain this selected value. They are excluded from the schema. This export does not model interactions.

The schema preserves exact numeric spelling, including values beyond machine integer or floating-point ranges. Your downstream tool must use exact arithmetic if those distinctions matter. Typed deserialization alone does not enforce bounds, steps, presence or other model constraints.

Refused descriptions

Export withholds the entire schema if any needed selected description contains unsupported meaning, even in an optional map entry or an alternative. It does not offer a lossy fallback. The first export supports no format, sdfType, contentFormat, pattern, Direct items descriptions, unknown data types or extension qualities. Context needs explicit nullable because its draft does not establish the ordinary default. Unestablished object structure, unavailable references, malformed supported constraints and exhausted processing limits also prevent export.

These boundaries preserve existing semantics. For example, format denotation can change equality, patterns depend on engine behavior, and Direct items have restricted vocabulary and unavailable nullability. Copying those keywords would make a stronger fidelity claim than the existing model supports.

Composition and export share the configured work, node, reference and derived allocation allowances. Exported schema traversal has a depth ceiling of 64 and uses the report byte ceiling, reserving space for a refusal first. If mandatory identity cannot fit, the library returns a request error rather than a report. Existing check and inspection report versions do not change.

Library

#![allow(unused)]
fn main() {
use esdieff::{Catalogue, SampleKind, SchemaRequest, SourceInput};

let catalogue = Catalogue::from_inputs(&[SourceInput::supplied(
    "sensor", br#"{"sdfProperty":{"reading":{"type":"number","minimum":0}}}"#,
)])?;
let document = catalogue.source_id("sensor").unwrap();
let result = catalogue.export_schema(SchemaRequest::new(
    document, SampleKind::Property, "/sdfProperty/reading",
))?;
if let Some(schema) = result.schema() {
    println!("{schema}");
} else {
    println!("{}", result.to_json());
}
Ok::<(), &'static str>(())
}

The comparison fixtures in tests/schema_export.rs use independently expected samples, Esdieff Sample-value checking and a separate Draft 2020-12 validator with exact arithmetic. They include the maintained thermostat model, deliberately authored constraints and refusal cases. These fixtures establish the bounded bridge, not equivalence for unsupported SDF meaning. See ADR 0052.