Orleans.Lattice.Schema 9.9.0

Orleans.Lattice.Schema

Schema enforcement and schema versioning for Orleans.Lattice, built on a shared, serializable value-to-value transform IR - LatticeValueTransform - that is the sibling of the core boolean predicate IR (LatticePredicateNode). Where the predicate IR answers "does this value's JSON document match?", the transform IR answers "what new JSON document does this value become?".

The package ships two independent, strictly opt-in capabilities:

• Schema enforcement (AddLatticeSchemaEnforcement(...)) - per-tree, server-side validation of writes against a LatticeSchemaPolicy (JSON, UTF-8, maximum byte length, regex, or a structured predicate), managed through ILatticeSchemaAdmin. A non-compliant local write throws LatticeSchemaViolationException; under strict ingest a non-compliant ingested item that reaches the check (a replicated typed-CRDT entry, or an entry of a replicated atomic batch) is dead-lettered instead of applied, while a plain (non-atomic) last-writer-wins replication apply and a backup restore write below the check and are not validated. Existing data is brought into compliance by a shadow-build-and-cutover remediation (ILatticeSchemaRemediationAdmin), and ILatticeSchemaComplianceAdmin audits a tree without changing it.
• Schema versioning (AddLatticeSchemaVersioning(...)) - a per-value schema-version envelope, managed through ILatticeSchemaVersionAdmin, with read-time upcasting to the tree's monotonic target version and an eager re-stamping migration.

These in-process admin services perform no authorization of their own; the Orleans.Lattice.Api.Schema facade authorizes remote callers. See the schema documentation.

Design

LatticeValueTransform is an immutable, Orleans-serializable discriminated tree, evaluated server-side against a value's UTF-8 JSON document to produce new UTF-8 JSON bytes. Its node kinds cover additive evolution, rename, drop, and default-fill:

• Passthrough - copy the input document as the starting point, then apply an ordered pipeline of member operations.
• SetMember(path, valueExpression) - set or overwrite a top-level member.
• DropMember(path) - remove a top-level member.
• RenameMember(from, to) - move a top-level member.

Value expressions read from the input document and produce the value a SetMember writes:

• Member(path) - read a member from the input document.
• Const(value) (node kind Constant) - a literal captured at translation time (reuses the core LatticeConstant).
• Conditional(condition, thenExpression, elseExpression) - where condition embeds a core LatticePredicateNode, so the boolean IR becomes a sub-node (the default-fill primitive).
• Compute(operator, operands...) - a minimal computed field (Concat, Coalesce).

Client translator

LatticeValueTransformTranslator lowers a client-side Expression<Func<TOld, TNew>> (or Expression<Func<T, T>>) into the IR with a tight allowlist, throwing NotSupportedException at translation time on the client naming the offending construct - exactly like LatticePredicateTranslator.

DI escape hatch

ILatticeValueTransform is a host-supplied byte[] -> byte[] transform identified by a stable id, for logic the declarative IR cannot express and for opaque / plain-text values the JSON IR cannot navigate. Register instances with AddLatticeValueTransform(...) and resolve one by id through ILatticeValueTransformRegistry.

Determinism

Both seams are serializable so a transform can be persisted on a shadow-build coordinator. The evaluator is deterministic and total per value: it throws a clear exception on malformed input rather than silently corrupting a value, so a consumer can abort a shadow build cleanly.