Use with SAP CAP

Keep `@sap/cds-rfc` unchanged and replace only its native low-level connector with `open-rfc`.

open-rfc does not publish a CAP plugin. SAP's package continues to own model imports, destination resolution, Cloud SDK integration, multitenancy, and CAP lifecycle behavior.

Install with npm 11

Declare open-rfc as a direct dependency and use a nested root override:

{
  "dependencies": {
    "@sap/cds": "9.9.2",
    "@sap/cds-rfc": "2.2.1",
    "open-rfc": "0.2.3"
  },
  "overrides": {
    "@sap/cds-rfc": {
      "@sap-rfc/node-rfc-library": "$open-rfc"
    }
  }
}

The @sap/cds version shown is the pinned compatibility example; use the exact version supported by your CAP application. Keep @sap/cds-rfc unchanged and pin open-rfc to the exact published release.

To evaluate an exact tarball received through a trusted channel, change only the direct open-rfc specifier:

{
  "dependencies": {
    "open-rfc": "file:../artifacts/open-rfc-0.2.3.tgz"
  }
}

Keep the nested $open-rfc override unchanged.

Tarball evaluation checks the connector bytes and override shape, but it does not prove npmjs registry resolution. Treat installation from npmjs as a separate verification using the exact published version and a fresh lockfile.

Commit the generated package-lock.json. Verify the installed tree:

npm explain @sap-rfc/node-rfc-library
npm ls open-rfc @sap/cds-rfc

The first command must show that the low-level dependency resolves to open-rfc. Do not override @sap/cds-rfc itself, do not add a project-owned CAP package, and do not change the CAP service implementation path.

Use the exact published open-rfc version from the release record, not a floating range. The $open-rfc reference tells npm to use the exact specifier from the root dependency and avoids duplicating it in the override.

If npm reports EOVERRIDE, confirm that open-rfc is a root dependency and that the nested override uses exactly $open-rfc. Do not copy a different version into the override. If an older lockfile still resolves the native connector, regenerate it in a review branch with npm 11, run the two inspection commands above, and review the lock diff before committing. A stale node_modules directory does not demonstrate reproducibility; a clean npm ci from the committed lockfile must produce the same tree.

Importer ownership

The override changes only the low-level runtime connector. It does not add, test, or change SAP's cds import --from rfc command, its flags, or its generated file layout. Follow the documentation shipped with the exact installed @sap/cds-rfc and @sap/cds versions for importer setup, and review every generated diff before committing it.

Generated metadata can reveal customer-specific object names and documentation. Treat it as project data and never attach it to a public issue. A successful importer run does not test the open-rfc runtime override or the application's live value and transaction shapes.

Configure a direct service

Use CAP's ordinary kind: "rfc" configuration. The example host is synthetic; inject credentials from deployment secrets rather than package.json:

{
  "cds": {
    "requires": {
      "SYS": {
        "kind": "rfc",
        "model": "srv/external/SYS",
        "credentials": {
          "ashost": "sap.example.invalid",
          "sysnr": "00",
          "client": "001"
        }
      }
    }
  }
}

Application code remains unchanged:

const cds = require("@sap/cds");

async function callSystem() {
  const system = await cds.connect.to("SYS");
  return system.send("STFC_CONNECTION", {
    REQUTEXT: "hello from CAP",
  });
}

module.exports = { callSystem };

Keep the route shape in source control and inject its credentials through the ordinary secret/configuration mechanism supported by the exact CAP version. The compatibility tests pass a structured CDS_CONFIG object to an unchanged CAP child, but this project does not prescribe an untested .env, binding, or mounted-file convention as a public contract. Verify the resolved service privately. Any effective CAP configuration output can contain credentials and must not enter CI logs or bug reports.

Route boundary

This release supports only direct application-server destinations. Message server and SAProuter are implemented and tested offline but remain unsupported previews in this release; their presence in the connector does not put them in the beta support contract. WebSocket invocation and Cloud Connector principal propagation are also unsupported and the beta provider rejects their missing capabilities before business I/O. A service binding or a successful preview connection does not make a route beta supported.

The connector never owns CAP tenant selection or destination lookup. It accepts the final connection properties and authentication material produced by the unchanged SAP layer, validates the supported subset, and owns the RFC transport from there.

Transactions and shutdown

Keep transaction boundaries in the unchanged SAP plugin or application layer. Calls in one logical unit of work must stay on the same modern RFCConnection; a successful commit or rollback ends that cycle. A timeout, cancellation, disconnect, or failed terminal operation is never replayed on a new connection. Reconcile the business outcome, close the failed connection, and let the application open a new one only for later work.

The modern connector façade used by unchanged @sap/cds-rfc has a fixed 45,000 ms operation bound and no per-execute() timeout argument. An application-level Promise.race() or HTTP deadline does not cancel RFC work. Use the connector lifecycle to close and join active operations, and treat a timeout after a possible send as uncertain. See the modern API lifecycle and uncertain-send rule.

During shutdown, stop accepting new CAP requests before closing connector resources. Do not log resolved destination objects because they can contain credentials or propagated identity material.

Test the exact application

Test every RFM value shape, route, timeout, cancellation, and transaction behavior your application uses. A disconnect after an uncertain send is never safe to replay automatically.