> We don't have a working Dockerfile for .Net. [Fill out the form](https://docs.google.com/forms/d/e/1FAIpQLSdxJDGFJl5oJ06rG7uqtw1rsSBZpUhv_s9HHtw80cytkh2X-Q/viewform?usp=pp_url&entry.25798127=.Net)
> and let us know if you'd like a Dockerfile for .Net.

{{< /tab >}}
{{< /tabs >}}

## Configure the metadata file

To start the backend service of your extension inside the VM of Docker Desktop, you have to configure the image name
in the `vm` section of the `metadata.json` file.

```json
{
  "vm": {
    "image": "${DESKTOP_PLUGIN_IMAGE}"
  },
  "icon": "docker.svg",
  "ui": {
    ...
  }
}
```

For more information on the `vm` section of the `metadata.json`, see [Metadata](../architecture/metadata.md).

> [!WARNING]
>
> Do not replace the `${DESKTOP_PLUGIN_IMAGE}` placeholder in the `metadata.json` file. The placeholder is replaced automatically with the correct image name when the extension is installed.

## Invoke the extension backend from your frontend

Using the [advanced frontend extension example](frontend-extension-tutorial.md), we can invoke our extension backend.

Use the Docker Desktop Client object and then invoke the `/hello` route from the backend service with `ddClient.
extension.vm.service.get` that returns the body of the response.

{{< tabs group="framework" >}}
{{< tab name="React" >}}

Replace the `ui/src/App.tsx` file with the following code:

```tsx

// ui/src/App.tsx
import React, { useEffect } from 'react';
import { createDockerDesktopClient } from "@docker/extension-api-client";

//obtain docker desktop extension client
const ddClient = createDockerDesktopClient();

export function App() {
  const ddClient = createDockerDesktopClient();
  const [hello, setHello] = useState<string>();

  useEffect(() => {
    const getHello = async () => {
      const result = await ddClient.extension.vm?.service?.get('/hello');
      setHello(JSON.stringify(result));
    }
    getHello()
  }, []);

  return (
    <Typography>{hello}</Typography>
  );
}

```

{{< /tab >}}
{{< tab name="Vue" >}}