rddads / X# RDD compatibility

OpenADS’ ace64.dll / ace32.dll is a drop-in replacement for the Advantage Client Engine. Two third-party RDDs link against it by name:

  • Harbour contrib/rddads — covered end-to-end since v0.1.0-rc1 (the first Harbour smoke).
  • X#’s AXDBFCDX RDD (ADSRDD.prg) — covered locally + over the wire since v1.0.0-rc19 (M12.22 / M12.23).

This page documents the X# RDD work and is the canonical reference for what each of the X#-specific exports actually does.

How X# binds OpenADS

X# ADSRDD.prg performs LoadLibrary("ace32.dll") (or ace64.dll) and resolves every entry point by name through GetProcAddress. The X# Advantage RDD calls a much wider surface than Harbour’s contrib/rddads, including a set of versioned overloads (AdsCreateTable90, AdsCreateIndex90, etc.) that exist to absorb the charset / collation / page-size parameters newer ACE builds added.

OpenADS therefore exports every Ads*NN name X# binds; most forward to the base signature, a few are accept-and-ignore for session / statement toggles that don’t apply to a clean-room implementation, and the genuinely-unimplemented return AE_FUNCTION_NOT_AVAILABLE so the X# runtime falls back to its own client path.

M12.22 — versioned ACE overloads

Export Behaviour
AdsConnect26 Forwards to AdsConnect60.
AdsCreateTable71 / AdsCreateTable90 Forward to AdsCreateTable (drop charset / collation / page-size).
AdsOpenTable90 Forwards to AdsOpenTable80.
AdsCreateIndex90 Forwards to AdsCreateIndex61 after re-mapping flags.
AdsDDAddTable90 Forwards to AdsDDAddTable.
AdsDDCreateRefIntegrity62 Forwards to AdsDDCreateRefIntegrity.
AdsFindFirstTable62 / AdsFindNextTable62 Forward to base.
AdsGetDateFormat60 Forwards to AdsGetDateFormat.
AdsGetExact22 Forwards to AdsGetExact.
AdsReindex61 Forwards to AdsReindex.
AdsRestructureTable90 Forwards to AdsRestructureTable.
AdsGetBookmark60 / AdsGotoBookmark60 Round-trip the recno as a 4-byte blob.
AdsCancelUpdate90 / AdsSetProperty90 Accepted no-ops.
AdsFindConnection25 / AdsGetTableHandle25 Report not-found — OpenADS keys by handle, not path / name.

M12.23 — the X# export gap

A live run of X#’s AXDBFCDX against OpenADS’ DLL surfaced ~45 more entry points ADSRDD.prg binds by name. The behaviour:

  • Field setters (AdsSetField, AdsSetEmpty, AdsSetNull, AdsSetShort, AdsSetMoney, AdsSetTime, AdsSetTimeStamp) — all handle the ACE “field name or 1-based ordinal cast to a pointer” idiom (X#’s _FieldSub calls AdsGetFieldType / Length / Decimals by ordinal, passing a tiny pointer value the old code dereferenced as a string).
  • Field readers (AdsGetDate, AdsGetMemoBlockSize, AdsGetTableOpenOptions, AdsGetBookmark) — real implementations.
  • Cursor helpers (AdsCancelUpdate, AdsContinue, AdsEval*Expr) — AdsCancelUpdate is an accept-and-ignore; the others return AE_FUNCTION_NOT_AVAILABLE so X# falls back.
  • RI / unique / autoinc enforcement toggles — accept-and-ignore (the underlying enforcement still happens through AdsCreateIndex / DD).
  • AdsStmt* helpers — return AE_FUNCTION_NOT_AVAILABLE; X#’s SQL surface routes around them.

Semantics fixes that shipped with M12.23

These looked like “missing exports” from the X# RDD’s point of view, but were actually wrong behaviour in existing entries:

  • AdsAppendRecord auto-locks the new record. ACE semantics for non-exclusive tables — X#’s GoHot refuses to write a record it sees as unlocked.
  • AdsIsRecordLocked / AdsLockRecord / AdsUnlockRecord honour recno == 0 = current record and report the real lock state instead of stubbing 0.
  • AdsCreateIndex61 / AdsCreateIndex90 option-bit fix. The “descending” flag is ADS_DESCENDING (0x08), not 0x02 — 0x02 is ADS_COMPOUND, which X#’s ADSRDD always sets for CDX orders, so the old mask built every X# order descending and DbGoTop landed on the last key.
  • AdsCreateTable / AdsCreateTable90 stage an empty .fpt next to the .dbf when the field list has an M field (using usMemoBlockSize, default 64). Without it Connection::open_table can’t attach a memo store and any memo write fails “memo store not attached”.

Remote-server X# (M12.23, rc19)

Three more fixes so X#’s ADSRDD drives openads_serverd over the wire (AdsConnect60("tcp://host:port/<datadir>", ADS_REMOTE_SERVER) → AX_SetConnectionHandle → DbUseArea):

  • remote_field_index honours the “field name OR 1-based ordinal cast to a pointer” idiom — same as the local side.
  • The remote AdsOpenTable branch defaults a missing extension to .dbf (X# passes the bare table name for remote tables).
  • AdsGetTableFilename gained a remote path (returning the opened name) instead of failing AE_INTERNAL_ERROR — X#’s Open calls it right after _FieldSub.

Test harness 

tests/smoke/xsharp/
├── AdsSmoke.prg          # local: ace64.dll directly
└── AdsSmoke_remote.prg   # remote: openads_serverd over tcp://

Both pass end-to-end against OpenADS:

  • Local smoke: DbCreate (incl. an M field) → DbUseArea → OrdCreate ×2 → DbAppend + FieldPut ×4 → DbCommit → NAME-order GoTop / Skip ± / GoBottom / Eof → DbSeek hit + miss → memo round-trip → DbDelete / DbRecall → replace a key field + re-read through the CITY order → DbCloseArea.
  • Remote smoke: opens customer.dbf on the server and does read / nav (RecCount / GoTop / Skip ± / GoBottom / Eof / FieldGet).

Doctest coverage: tests/abi_versioned_overloads_test.cpp (local) and tests/abi_remote_overloads_test.cpp (over the wire, gated on -DOPENADS_TEST_REMOTE=ON).

Follow-ups landed in rc20+ from X# feedback

  • rc21 / M12.24 — AdsGetLastTableUpdate real signature matches ACE (UNSIGNED8* pucDate, UNSIGNED16* pusLen); AdsSetDateFormat is no longer a no-op; AdsSetAOF returns success + ADS_OPTIMIZED_NONE on non-optimisable expressions instead of error 7200.
  • rc22 / M12.25 — AdsCreateTable stamps today’s date into the DBF header up front (matches ACE), so a fresh create+open reports today instead of 1900-00-00 until the first DbAppend.
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