The Vee Link: SysML ↔ STEP (stepper + pyoslc)¶

sysmlpy + stepper + pyoslc form a Systems-Engineering Vee toolchain: this page documents the SysML side of the joins.

     requirements & design              geometry & PMI
     (left/middle of Vee)               (right of Vee)
     .sysml  —  sysmlpy  —  OSLC  —  stepper  —  .stp
              parse/analyze   ^  parse/structure
                              │
                    pyoslc serves BOTH sides
                    as one OSLC catalog
                              │
                 released configuration = baseline
                 (hash-pinned, verifiable)

qn_registry() — the SysML identity you expose¶

Every to_interchange(stable_ids=True) export carries a side table mapping each named element's declared qualified-name path to its stable interchange @id:

import sysmlpy
from sysmlpy import to_interchange, qn_registry

m = sysmlpy.loads("""
package NistModel {
    part def 'NIST Test Case 1' {
        attribute thrust : Real;
    }
}
""")
doc = to_interchange(m, stable_ids=True)
print(qn_registry(doc)["NistModel.'NIST Test Case 1'"])
# sysml:45305c0c-…  (content-addressed; survives unrelated edits)

Facts pinned by tests (tests/qn_registry_test.py):

keys are deduped declared QN paths (the visitor dict's wrapper nesting must not leak);
values equal the corresponding graph element's @id;
the registry is stable across export → import → export;
explicit ids (doc /* @id: … */ comments) surface verbatim;
position-id exports yield {} (no identity to expose);
after reconcile_ids adoption the registry is remapped with the graph, so it never dangles.

Quoted short names KEEP their quotes in the keys — downstream matchers strip ' before comparing against other tools' titles.

What consumes it¶

pyoslc /oslc/step/vee posts {"registry": qn_registry(doc)} to auto-link SysML elements to STEP AP242 products by leaf name — the identity edge is then queryable from both directions through the OSLC API.
pyoslc baselines snapshot the link table into every released configuration — a baseline is therefore also a record of which SysML elements realized which geometry at release time.

Serving SysML as OSLC¶

The Saturn V example (pyoslc/examples/saturn_v/) already serves this repo's parsed models as OSLC SysML resources; see that repo's docs/DOMAIN_DEVELOPMENT.md. The STEP domain tutorial (stepper's mkdocs site, "Serving as OSLC") covers the geometry side.

Baselines on this side¶

A pyoslc baseline pins the .sysml source bytes (hash) AND the derived interchange payload (this repo's stable-ids export) — so a released configuration is verifiable from either side:

re-hash the pinned .sysml and compare with the baseline,
or re-run to_interchange and compare with the pinned payload (they must agree byte-for-byte thanks to stable ids).

The SysML-side guarantee that makes this work: stable ids are content-addressed — docs/stable-identities.md carries the full identity analysis.