## AutoConnect::begin logic sequence

The following parameters of [AutoConnectConfig](apiconfig.md) affect the behavior of [AutoConnect::begin](api.md#begin) function and control a logic sequence. They are also evaluated on a case-by-case basis and may not be valid in all situations. The sketch must consider the role of these parameters and the conditions under which they will work as intended. You need to understand what happens when using these parameters in combination.

- [immediateStart](apiconfig.md#immediatestart) : The captive portal start immediately, without the 1st-WiFi.begin.
- [autoReconenct](apiconfig.md#autoreconnect) : Attempt re-connect with past SSID by saved credential.
- [portalTimeout](apiconfig.md#portaltimeout) : Time out limit for the portal.
- [retainPortal](apiconfig.md#retainportal) : Keep DNS server functioning for the captive portal.

The following chart shows the AutoConnect::begin logic sequence that contains the control flow with each parameter takes effect.

<img align="center" src="images/process_begin.svg">

For example, [AutoConnect::begin](api.md#begin) will not end without the [**portalTimeout**](apiconfig.md#portaltimeout) while the connection not establishes, but WebServer will start to work. And the DNS server also will start to make the captive portal detection to the client. The custom web page now responds correctly with the behavior of the two internally launched servers, and the sketch looks like working. But AutoConnect::begin does not end yet. Especially when invoking AutoConnect::begin in the **setup()**, control flow does not pass to the **loop()**.

As different scenes, you may use the [**immediateStart**](apiconfig.md#immediatestart) effectively. Equipped the external switch to activate the captive portal with the ESP module, combined with the [**portalTime**](apiconfig.md#portaltimeout) and the [**retainPortal**](apiconfig.md#retainportal) it will become WiFi active connection feature. You can start [AutoConnect::begin](api.md#begin) at any point in the **loop()**, which allows your sketch can behave both the offline mode and the online mode.

The [**retainPortal**](apiconfig.md#retainportal) option allows the DNS server to continue operation after exiting from [AutoConnect::begin](api.md#begin). AutoConnect traps captive portal detection from the client and redirects it to the AutoConnect menu. That trap will answer all unresolved addresses with SoftAP's IP address. If the URI handler for the source request is undefined, it returns a 302 response with `SoftAPIP/_ac` to the client. This is the mechanism of AutoConnect's captive portal. Captive portal probes will frequently occur while you are attempting on the client device's WiFi connection Apps and these implementations are varied each OS, so it not realistic to identify all probing URIs. Therefore, while retainPortal is enabled, it is not preferable to executing the sketch under the WiFi connection Apps on the client device. (Probably not work correctly) You need to exit from the WiFi connection Apps once.

Please consider these kinds of influence when you make sketches.

!!! info "The AutoConnect::begin 3rd parameter"
    Another parameter as the [3rd parameter](api.md#begin) of AutoConnect::begin related to timeout constrains the connection wait time after WiFi.begin. It is the **CONNECTED** judgment of the above chart that it has an effect.