> ```
>
> Please make sure this step is carried out, without this step PostgreSQL notification targets will not work,
> an error message will be shown on the console upon server upgrade/restart, make sure to follow the above
> instructions appropriately. For further questions please join our <https://slack.min.io>

When you install FastAPI, it comes with a production server, Uvicorn, and you can start it with the `fastapi run` command.

But you can also install an ASGI server manually.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then you can install the server application.

For example, to install Uvicorn:

<div class="termy">

```console

	return nil
}

func (target *MQTTTarget) init() error {
	return target.initOnce.Do(target.initMQTT)
}

func (target *MQTTTarget) initMQTT() error {
	args := target.args

	// Using hex here, to make sure we avoid 23
	// character limit on client_id according to
	// MQTT spec.
	clientID := fmt.Sprintf("%x", time.Now().UnixNano())

	options := mqtt.NewClientOptions().
		SetClientID(clientID).

      blocker.setOwner(Thread.currentThread());
      if (compareAndSet(currentRunner, blocker)) {
        // Thread.interrupt can throw arbitrary exceptions due to the nio InterruptibleChannel API
        // This will make sure that tasks don't get stuck busy waiting.
        // Some of this is fixed in jdk11 (see https://bugs.openjdk.org/browse/JDK-8198692) but
        // not all.  See the test cases for examples on how this can happen.
        try {

	for i := range deleteObjectsReq.Objects {
		deleteObjectsReq.Objects[i].ObjectName = trimLeadingSlash(deleteObjectsReq.Objects[i].ObjectName)
		objects[i] = deleteObjectsReq.Objects[i].ObjectV
	}

	// Make sure to update context to print ObjectNames for multi objects.
	ctx = updateReqContext(ctx, objects...)

	// Call checkRequestAuthType to populate ReqInfo.AccessKey before GetBucketInfo()

   */
  private fun planReuseCallConnection(): ReusePlan? {
    // This may be mutated by releaseConnectionNoEvents()!
    val candidate = call.connection ?: return null

    // Make sure this connection is healthy & eligible for new exchanges. If it's no longer needed
    // then we're on the hook to close it.
    val healthy = candidate.isHealthy(doExtensiveHealthChecks)
    var noNewExchangesEvent = false

```

Snapshot builds are [available][snap]. [R8 and ProGuard][r8_proguard] rules are available.

Also, we have a [bill of materials (BOM)][bom] available to help you keep OkHttp artifacts up to date and be sure about version compatibility.

```kotlin
    dependencies {
       // define a BOM and its version
       implementation(platform("com.squareup.okhttp3:okhttp-bom:5.3.0"))

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

But possibly the most important part of the callback is making sure that your API user (the external developer) implements the *external API* correctly, according to the data that *your API* is going to send in the request body of the callback, etc.

		return 1, err
	}

	// This wrapper uses complicated machinery to run iOS binaries. It
	// works, but only when running one binary at a time.
	// Use a file lock to make sure only one wrapper is running at a time.
	//
	// The lock file is never deleted, to avoid concurrent locks on distinct
	// files with the same path.
	lockName := filepath.Join(os.TempDir(), "go_ios_exec-"+deviceID+".lock")

/// info

FastAPI added support for `Annotated` (and started recommending it) in version 0.95.0.

If you have an older version, you would get errors when trying to use `Annotated`.

Make sure you [Upgrade the FastAPI version](../../deployment/versions.md#upgrading-the-fastapi-versions){.internal-link target=_blank} to at least 0.95.1 before using `Annotated`.

///

### Import `Depends` { #import-depends }