How to Handle Date and Time with Simple Approach !!

How to Handle Date and Time with Simple Approach !!

Transcript

1. DATE AND TIMEZONE
2. ABOUT ME @nsisodiya Narendra Sisodiya Engineering Manager cum Software Architect at Hotelsoft Inc. I ὑ JavaScript, I ὑ React.js, I ὑ Node.js,
3. WTF FACTS ABOUT TIME/DATE ETC ➤ Samoa - 30 December 2011 DO NOT EXIST ➤ Timezone Offset can change for future dates ➤ Storing time with timezone is problematic ➤ At the DST transition, there is time jump or time repeated. ➤ That means, Day duration is not exactly 24 Hours, for some days ! ➤ TIMEZONE etc is a big mess, DO NOT DEAL with It Until is absolute needed !!
4. DIFFERENCE BETWEEN DAY AND TIMESTAMP 2016-07-14 start time of day end time of day FULL DAY = 86400000 MILLISECONDS (NOT ALWAYS TRUE) TIMESTAMP = EXACT MILLISECOND, TIME MOMENT
5. 3 TYPES OF ATTRIBUTES DAY DAY + TIME Price of Hotel room is $200 per night on 29 July 2016 Rohan was absent on 1st April 2016 DAY + TIME + TIMEZONE In India, we will start meeting at 3:30PM at 2nd July 2016 we will start meeting at 3:30PM at 2nd July 2016 eat banana at 3:30PM of 3rd July 2016 and get rich TIMEZONE LESS WITH TIMEZONE TIMEZONE LESS
6. 3 TYPES OF ATTRIBUTES DAY DAY + TIME DAY + TIME + TIMEZONE TIMEZONE LESS WITH TIMEZONE TIMEZONE LESS YYYY-MM-DD is just sufficient 2016-04-09T20:18:48-05:00 2016-04-09 2016-04-09T20:18:48Z Z = UTC 1469183888786 2016-04-09 T20:18:48Z Z = UTC UTC TIMESTAMPS
8. OMG - DATE IS MISNOMER https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Date Source
9. OMG - DATE IS MISNOMER
10. WTF ? DATE IS MEANT FOR SINGLE MILLISECOND ?? YES
11. ROOT CAUSE OF PROBLEMS - RC 1 JavaScript Dates are meant for exact `milliseconds with client timezone` & We do not have any Construct like new Day(‘2016-07-27’), WE end up using `Date` constructor for Day wise attributes.
12. REMEMBER AGAIN If you try to represent a “Day Wise Attribute” with “millisecond” you will obviously get problems
13. BECAUSE MILLISECOND CAN FALL ON ANY DATE 2016-07-12 2016-07-13 US 2016-07-12 2016-07-13 India new Date()
14. ROOT CAUSE OF PROBLEMS - RC 2 Serialised String flow over wire and Serialisation + DeSerialisation may not return exact object. DeSerialisation (Serialisation(☺)) = ☻
15. YOU NEED TO UNDERSTAND JSON PROTOCOL Object Serialisation Parse back to Object
16. YOU NEED TO UNDERSTAND JSON PROTOCOL you may or may not get the same object back in the whole process
17. YOU NEED TO UNDERSTAND JSON PROTOCOL var OUT = ultapulta(IN)
18. YOU NEED TO UNDERSTAND JSON PROTOCOL OUT IN undefined was removed String Object get converted into string Date Object get converted into UTC strings
19. ROOT CAUSE OF PROBLEMS - RC 4 Irrespective of What Library you use, UTC TimeStamps (like -“2016-08-03T16:34:47.676Z" ) flow over wire which do not carry timezone info !
20. WTF — ON WIRE - TIMEZONE INFO DO NOT FLOW “2016-07-17T10:00:00.000Z" flow over wire
21. ROOT CAUSE OF PROBLEMS - RC 4 UTC string flow over wire and Client and Server may have there different understanding about timezone ! That create problem Client Server 2016-08-04T08:00:00.000Z 2016-08-04 1:30 PM In India 2016-08-03 10:00PM In US/Hawaii
22. ROOT CAUSE OF PROBLEMS - RC 4 Slide from Maggi Pint - https://maggiepint.com/2016/04/28/javascript- mn-2016-04-27/ - Slider number 17 Even if you try to send 2016-04-09T19:39:00-05:00
23. UTC STRINGS - FACTS ➤ On WIRE, UTC timestamp strings travel. ➤ You do not send timezone on wire. ➤ UTC Strings, DO NOT carry “TIMEZONE INFO” ➤ 2016-04-09T20:18:48Z ➤ Remember, Z means UTC
24. ISO 8601 ➤ Date with time = 2016-07-22T10:38:08.786Z = 1469183888786 AT INDIA AT USA ➤ JSON representation is always same
25. SOLUTION
26. FIRST DEFINE : TYPE OF ATTRIBUTE AND PURPOSE Q1 ) Is it a DayWise attribute ? or Day + TIME ? or Day + TIME + TIMEZONE ?
27. EXAMPLE 1 - HOTEL BOOKING MANAGER ➤ Assume, Hotel has only one room category and they have fixed rate during whole day. ➤ Hotel can be in any Country ➤ You need to show nearby Hotels to your current Location. ➤ Hotel Rates are too be shown with proper currency code. ➤ This is the most simple example and There is no possibility to have any DateTime or Timezone issue AT ALL.
28. TIMEZONE, NEW DATE MOMENT.TZ FREE APPROACH
29. Hotels in India, client in India http://www.booking.com/
30. India Page Hotels in US, client in US http://www.booking.com/
31. Where is the Problem
32. ➤ 10 August of New Delhi and Los Angeles are different there is a timezone difference. ➤ BUT ➤ IT DOES NOT MATTERS ➤ YES ➤ If on UI, Two Pages Look exactly similar than Technically there should not be any difference on their Backend Implementation!
33. HOW BOOKING.COM MANAGE IT ! ➤ And this how booking deal with it.
34. SLIGHTLY BETTER BUT EXACTLY EQUAL APPROACH This is YYYY-MM-DD format,
35. FROM DATE PICKER TO DB - USE “YYYY-MM-DD” This is a timezone Free Approach This is Simple and Tension free
36. FROM DATE PICKER TO DB - USE “YYYY-MM-DD” 2014-01-05 JavaScript CLIENT DB There is no confusion between server to client communication 2014-01-05 2014-01-05
38. SIMPLE MATH You can use any Date Library but use it for Processing. do not exchange Date or Moment Object.
39. EXAMPLE 2 - TWITTER KIND APPLICATION ➤ Multiuser app. ➤ User Tweet multiple times in a day. ➤ Tweet should show local time to a user, irrespective of where it is created !!
40. Same UI, Show Different Time, Based on Location India Client US Client
41. USE UNIX TIMESTAMPS
42. FROM DATE PICKER TO DB - USE - UNIX TIMESTAMPS 1468564804000 JavaScript CLIENT DB There is no confusion between server to client communication 1468564804000 1468564804000
43. India Client US Client
44. FROM DATE PICKER TO DB - USE - UNIX TIMESTAMPS This is a timezone Free Approach This is Simple and Tension free
45. GIVE ME ALL TWEETS ON 2016-04-15 15 April 2016 will be different based on Location of User
46. 1460703600000 1460789999999 1460658600000 1460744999999 2016-04-15 In America/ Los_Angeles 2016-04-15 In Asia/Kolkata (India)
47. THESE FUNCTIONS RUN ON SERVER
48. JavaScript DB APPLICATION SERVER $.ajax({ type: 'post', url: '/getAllTweetsOnDay', data: { giveDay: “2016-04-15” }, dataType: 'json' }); SELECT * FROM Tweets WHERE creation_dt BETWEEN 1460703600000 AND 1460789999999;