Which manner Clock » Instant calculates DST vigency in AI2?

[Lito]

I have been studying several topics that address the question of the vigency of Daylight Saving Time [DST] by calling certain Clock Properties and how it can positively or negatively interfere with the results of some operations.

But what I don't finish understanding is how 'Instant' decides this information.

Since there is no Clock Property that references a particular city or place that can be programmatically defined -and 'Instant' always knows accurately the Time zone and an eventual DST- I estimate that this information about the Time zone and DSTs take as reference internal time settings manually defined by the User on the Android device or from Sensor... but I am not very clear how this happens.

The Time zones are divided by bands »

But not necessarily an entire Time zone band adopts DST evenly throughout the whole track. According to individual provisions, there will be countries within this range that adopt the DST - starting and ending on different days and hours- and there will be countries (or States) that do not adopt it.

This means that so that 'Instant' can elucidate DST validity, somehow it is taking from device not only the reference of the Timezone defined, but also the place of the device... which means the same 'Instant' defined programmatically will have different results according to the Timezone and the Location of the User.... and even more: the vigency or not of DST will be specifically linked to this Location!

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My questions are:

1. Where do 'Instant' get the current Timezone? Is this done based on the device location sensor and later calculated? Or such information comes from UI?

2. Where did 'Instant' get the User Location? Is this done by the device location sensor? Or such information comes from UI?

3. To decide DST vigency, does AI2 use any specific API or any specific NTP Server [Network Time Protocol]?

4. If so, what would be this API or this NTP Server?

TYA

Lito @>-->---

[Anke]

App Inventor Clock problem

To understand this behavior, we have to be rigorous about the definitions of the terms Instant Duration An Instant is a milestone on the road of time. The road starts in the year 1970. Some Instants are Milestones in today's section of the road, starting at midnight, depending on where you got them (DatePicker vs TimePicker, etc.) You can tell you have an Instant when you try to display it as text and you get a lot of labelled details you did not expect. A Duration is a pure number of mil…

[ABG]

Vigency?

[SteveJG]

@Lito

To decide DST vigency, does AI2 use any specific API or any specific NTP Server [Network Time Protocol]?

• vigency = validity ... when is DST or ST in force?? perhaps

• Most smartphones update DST or ST depending on the device's current location.

automatically.

• How? See Regras de fuso horário  |  Android Open Source Project

• How your Android knows its time zone and whether DST is in use at the moment or not using using the Clock.

This show I am in the Central Time Zone and DST offset is 0 meaning standard time is in effect. Each device will provide that information for it's current location and what Google has in its record database. See the Time zone rules to understand how it does this.

[Anke]

vigency = Virtual Agency

Bewertungsprofil von vigency | Virtual Agency | ProvenExpert.com

[TIMAI2]

Difficult to automatically get whether DST is in place on the selected city without going online to find out, but this example should show you the correct time for any city, and allow you to see the time if DST is in place.

getCityZone.aia (13.2 KB)