<img class="shadow" src="/img/deployment/concepts/image01.png">

---

Now that we know the difference between the terms **process** and **program**, let's continue talking about deployments.

## Running on Startup

    `keepAliveDuration` but do not count against the pool-wide `maxIdleConnections` limit.

    This feature increases the client's traffic and the load on the server. Talking to your server's
    operators before adopting it.

 *  New in okhttp-android: `HttpLoggingInterceptor.androidLogging()` and
    `LoggingEventListener.androidLogging()` write HTTP calls or events to Logcat.

<img src="/img/async/concurrent-burgers/concurrent-burgers-05.png" class="illustration">

While waiting and talking to your crush, from time to time, you check the number displayed on the counter to see if it's your turn already.

Then at some point, it finally is your turn. You go to the counter, get your burgers and come back to the table.

systems is data "<abbr title="also called marshalling, conversion">serialization</abbr>" which is taking data from the code (Python) and converting it into something that can be sent through the network. For example, converting an object containing data from a database into a JSON object. Converting `datetime` objects into strings, etc.

Another big feature needed by APIs is data validation, making sure that the data is valid, given certain parameters. For example, that some field is an `int`,...

            firDiagnostic as KtPsiDiagnostic,
            token,
        )
    }
    add(FirErrors.BACKING_FIELD_IN_INTERFACE) { firDiagnostic ->
        BackingFieldInInterfaceImpl(
            firDiagnostic as KtPsiDiagnostic,
            token,
        )
    }
    add(FirErrors.EXTENSION_PROPERTY_WITH_BACKING_FIELD) { firDiagnostic ->
        ExtensionPropertyWithBackingFieldImpl(

 * deterministic.
 *
 * This class ensures that at most one thread is running at a time. This is initially the JUnit test
 * thread, which yields its execution privilege while calling [runTasks], [runNextTask], or
 * [advanceUntil]. These functions don't return until the task threads are all idle.
 *
 * Task threads release their execution privilege in these ways:
 *

    override val hasBackingField: Boolean
        get() = withValidityAssertion {
            val bindingContext = analysisContext.resolveSession.bindingContext
            return bindingContext[BindingContext.BACKING_FIELD_REQUIRED, descriptor] == true
        }

    override val isDelegatedProperty: Boolean
        get() = withValidityAssertion { descriptor.isDelegated }

    }

    if (queue.futureTasks.isNotEmpty()) {
      readyQueues.add(queue)
    }
  }

  /**
   * Returns an immediately-executable task for the calling thread to execute, sleeping as necessary
   * until one is ready. If there are no ready queues, or if other threads have everything under

        this.url = url
      }

    /**
     * Sets the URL target of this request.
     *
     * @throws IllegalArgumentException if [url] is not a valid HTTP or HTTPS URL. Avoid this
     *     exception by calling [HttpUrl.parse]; it returns null for invalid URLs.
     */
    open fun url(url: String): Builder {
      return url(canonicalUrl(url).toHttpUrl())
    }

    /**
     * Sets the URL target of this request.

{!../../../docs_src/custom_response/tutorial004.py!}
```

In this example, the function `generate_html_response()` already generates and returns a `Response` instead of returning the HTML in a `str`.

By returning the result of calling `generate_html_response()`, you are already returning a `Response` that will override the default **FastAPI** behavior.