go-tdsstack

A bounded TDS 7.4 server transport for Go applications. It supplies packet framing, TLS/login, RPC and prepared handle lifecycle, static read-only cursor snapshots, result tokens and exact scalar wire codecs.

The package does not parse SQL, infer SQL types, own database transactions, or bind application parameters. It uses native Go data and opaque application sessions. Applications supply explicit column descriptors before rows, even for empty and all-NULL results. Parameters retain their wire descriptors, including typed NULL.

server := &tds.Server{
    Database: "example",
    Handler: tds.Handler{
        Authenticate: authenticate,
        Execute: execute,
        Describe: describe,
        Reset: reset,
        Close: closeSession,
    },
}
listener, err := net.Listen("tcp", ":1433")
if err != nil {
    return err
}
return server.Serve(listener)

Authenticate returns application session state. Execute receives an untouched batch string, optional untouched declaration string, and typed native parameters. The application parses, validates, converts and binds these. Its callbacks must finish all parallel row producers before returning. Cancellation covers the whole request, including Describe. Pure Describe validates prepared or cursor shapes without executing a statement. The library never constructs SQL transaction text.

Metadata handles named procedure requests in the frontend. Transaction receives explicit wire actions. A requested transaction successor invokes the completion callback first and invokes begin only if completion succeeds. BeginRequest is an optional application scope boundary. Reset replaces application pooling state; Close releases it. The server never reads application session keys.

A result begins with Fields([]Column), followed by Row([]any) and optional Done(Completion). Completion explicitly communicates row counts, database changes, transaction state and further results. A handler with one result can omit Done; the transport finishes it with the emitted row count. Parallel row callbacks are serialized only at this output boundary. Each row is completely validated before publishing its ROW token, so malformed payloads cannot swallow an error token.

Use int64, float64, bool, string, []byte, or nil for ordinary wire values. Decimal carries an unscaled canonical integer string; no binary floating point conversion occurs. Temporal carries day ordinal, wire clock units and original offset minutes. These are transient protocol payloads, not persistent SQL types. The application performs scale, precision, calendar and implicit-cast semantics.

Prepared handles retain only opaque text and declarations. Cursor snapshots retain only bounded, cloned native payloads. Neither retains a query context, transaction, application session, callback closure, planner or storage object. Newly created handles become visible only after successful response publication. Failed or cancelled publication removes them.

Explicitly unsupported: MARS, integrated authentication, password changes, RESETCONNECTIONSKIPTRAN, nonstatic/updatable cursors, arbitrary output statement parameters, unsupported code pages and unrecognized wire types. Frontends determine which SQL grammar and type domains they support.

Verification:

go test -race ./...
go vet ./...

Tests include released client TCP/TLS/login/typed-result interoperability, exact 38-digit coefficient and 100ns/offset goldens, typed NULL, malformed packets, prepared lifecycle and pure describe, static cursor fetch positions and snapshots, transaction successors, attention/reuse, concurrent rows and failed publication.