---
title: "Configuration"
description: "Configuration — Node.js BabelQueue SDK (1.x)."
source: https://babelqueue.com/docs/babelqueue-node/1.x/configuration/
updated: 2026-06-06T00:00:00.000Z
---

# Configuration

The core is a codec, so there's almost nothing to configure — the "wiring" is
your own broker client plus a couple of optional behaviours.

## Envelope options

`EnvelopeCodec.make` takes options for the queue name (written to `meta.queue`)
and trace continuation across a hop:

```ts
import { EnvelopeCodec } from "@babelqueue/core";

const env = EnvelopeCodec.make(
  "urn:babel:orders:created",
  { order_id: 1042 },
  { queue: "orders", traceId: inbound.trace_id }, // omit traceId to mint a fresh one
);
```

## Dead-letter

On failure, wrap the envelope in an additive `dead_letter` block and publish the
copy to your dead-letter queue (e.g. `orders.dlq`):

```ts
import { annotate, EnvelopeCodec } from "@babelqueue/core";

const dlq = annotate(env, "failed", "orders", { attempts: 3, error: "boom" });
// publish EnvelopeCodec.encode(dlq) to the "orders.dlq" queue
```

`annotate` returns a copy — the original envelope is preserved unchanged inside
the dead-lettered message, so any-language consumer can still read it.

## Unknown-URN strategy

For adapters routing inbound messages, `UnknownUrnStrategy` (`FAIL`, `DELETE`,
`RELEASE`, `DEAD_LETTER`) describes what to do with a URN you don't handle.

Next: [Producing messages](/docs/babelqueue-node/1.x/producing-messages/).