# node-libcmt

Build Cartesi rollup applications in Node.js, talking directly to the machine — no HTTP server in between.

:::note
Temporarily published as `@deroll/cmio` while it is not an official Cartesi package.
:::

A Cartesi application receives **inputs** from the blockchain, processes them inside a deterministic Linux virtual machine (the Cartesi Machine), and produces verifiable **outputs**. This package is a native binding to [libcmt](https://github.com/cartesi/machine-guest-tools/tree/main/sys-utils/libcmt), the guest-side rollup library, so your Node.js code can process inputs and emit outputs with a few function calls:

```ts twoslash
import { Rollup } from '@deroll/cmio';

const rollup = new Rollup();

await rollup.run({
    advance(request, rollup) {
        // an input arrived from the blockchain — echo it back as a notice
        rollup.emitNotice(request.payload);
        return true; // accept
    },
    inspect(request, rollup) {
        // an off-chain query — answer with a report
        rollup.emitReport(request.payload);
    },
});
```

The same code runs unchanged in two environments:

* **Your development machine** — the binding embeds libcmt's *mock* IO driver: inputs come from local files, outputs are written next to them. Instant feedback, no emulator needed.
* **Inside the Cartesi Machine** — the binding talks to the real rollup device of the emulated riscv64 machine. A prebuilt binary ships in the package, so nothing is compiled at install time.

## Where to go next

* [Getting Started](/cmio/getting-started) — install the package and run your first application.
* [User Guide](/cmio/guide/handling-requests) — how requests, outputs and testing work.
* [Reference](/cmio/reference/rollup) — every binding method, fully typed.