Its Time To Share: Calendar Data Interchange

1
Its Time To ShareCalendar Data Interchange

• Michael J. Radwin, Yahoo! Inc.
• David Sklar, 24 Hour Laundry

OReilly Open Source Convention August 4, 2005
2
What youll learn today

• iCalendar (RFC 2445) is the One True interchange
  format
• Conforming to the iCalendar spec is easier said
  than done
• LAMP is the ideal tool to generate dynamic
  iCalendar data
• Time Zones cant live with em, cant live
  without em

3
Thirty Days Hath September
4
February 30, 1712
5
Calendar Software
Apple iCal
Lotus Notes
OSAF Chandler
Mozilla Sunbird
Palm Desktop
6
Supported Import Formats
7
iCalendar the De Facto Standard

• BEGINVCALENDAR
• PRODID-//Acme Software\, Inc./ExampleCalApp
  1.2.3//EN
• VERSION2.0
• CALSCALEGREGORIAN
• BEGINVEVENT
• SUMMARYHTTP Caching and Cache-busting
• DTSTARTTZIDUS/Pacific20050804T172000
• DURATIONPT45M
• ENDVEVENT
• BEGINVEVENT
• SUMMARYTax Day
• DTSTARTVALUEDATE20060415
• DTENDVALUEDATE20060416
• ENDVEVENT
• ENDVCALENDAR

8
Generating Calendar Data with LAMP
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cal.sql

• Schema for table to hold event data

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Event.php

• Classes to generate iCalendar output

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config.php

• Basic app/DB configuration

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calendar.php

• Generate iCalendar output

13
list.php

• Display human-readable (but ugly) event summary
  for debugging

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add.php

• Add a new event

15
iCalendar TIMTOWTRI

• There Is More Than One Way To Represent It

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iCalendar Event (Start End)

• BEGINVEVENT
• SUMMARYIce Cream Social
• LOCATIONExhibit Hall
• DTSTARTTZIDUS/Pacific20050804T152000
• DTENDTZIDUS/Pacific20050804T163000
• UID5FFB146A-8F4A-480E-B0B9-EC302B5DD8B6
• ENDVEVENT

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iCalendar Event (Start Duration)

• BEGINVEVENT
• SUMMARYIce Cream Social
• LOCATIONExhibit Hall
• DTSTARTTZIDUS/Pacific20050804T152000
• DURATIONPT1H10M
• UID5FFB146A-8F4A-480E-B0B9-EC302B5DD8B6
• ENDVEVENT

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iCalendar Event (GMT)

• BEGINVEVENT
• SUMMARYIce Cream Social
• LOCATIONExhibit Hall
• DTSTART20050804T222000Z
• DURATIONPT1H10M
• UID5FFB146A-8F4A-480E-B0B9-EC302B5DD8B6
• ENDVEVENT

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iCalendar Event (Floating Time)

• BEGINVEVENT
• SUMMARYIce Cream Social
• LOCATIONExhibit Hall
• DTSTART20050804T152000
• DURATIONPT1H10M
• UID5FFB146A-8F4A-480E-B0B9-EC302B5DD8B6
• ENDVEVENT

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iCalendar Interop Hurdle

• All-day Untimed Events

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All-day Untimed Event

• BEGINVEVENT
• SUMMARYMoms Birthday
• DTSTART20050507T000000
• DTEND20050507T235959
• RRULEFREQYEARLY
• UID15369079-4F9A-4D0A-9ABF-EC5F2F5F1C7F
• ENDVEVENT

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All-day Untimed Event

• BEGINVEVENT
• SUMMARYMoms Birthday
• DTSTART20050507T000000
• DTEND20050508T000000
• RRULEFREQYEARLY
• UID15369079-4F9A-4D0A-9ABF-EC5F2F5F1C7F
• ENDVEVENT

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All-day Untimed Event

• BEGINVEVENT
• SUMMARYMoms Birthday
• DTSTARTVALUEDATE20050507
• RRULEFREQYEARLY
• UID15369079-4F9A-4D0A-9ABF-EC5F2F5F1C7F
• ENDVEVENT

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All-day Untimed Event

• BEGINVEVENT
• SUMMARYMoms Birthday
• DTSTARTVALUEDATE20050507
• DURATIONP1D
• RRULEFREQYEARLY
• UID15369079-4F9A-4D0A-9ABF-EC5F2F5F1C7F
• ENDVEVENT

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All-day Untimed Event

• BEGINVEVENT
• SUMMARYMoms Birthday
• DTSTARTVALUEDATE20050507
• DTENDVALUEDATE20050507
• RRULEFREQYEARLY
• UID15369079-4F9A-4D0A-9ABF-EC5F2F5F1C7F
• ENDVEVENT

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All-day Untimed Event

• BEGINVEVENT
• SUMMARYMoms Birthday
• DTSTARTVALUEDATE20050507
• DTENDVALUEDATE20050508
• RRULEFREQYEARLY
• UID15369079-4F9A-4D0A-9ABF-EC5F2F5F1C7F
• ENDVEVENT

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Calendar Scheduling Protocols
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iCalendar Interchange Protocols
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iMIP Scheduling via Email

• BEGINVCALENDAR
• METHODREQUEST
• BEGINVEVENT
• SUMMARYPHP 7 Planning and Pub Crawl
• DTSTARTTZIDUS/Pacific20050804T193000
• DTENDTZIDUS/Pacific20050805T020000
• ORGANIZERCN"Michael Radwin"MAILTOmichael_at_radwi
  n.org
• ATTENDEECN"Rasmus Lerdorf"PARTSTATNEEDS-ACTION
  ROLEREQ-PARTICIPANTRSVPTRUEmailtorasmus_at_php.
  net
• ATTENDEECN"David Sklar"PARTSTATNEEDS-ACTIONRO
  LEREQ-PARTICIPANTRSVPTRUEmailtosklar_at_sklar.co
  m
• ATTENDEECN"Adam Tberg"PARTSTATNEEDS-ACTIONRO
  LEREQ-PARTICIPANTRSVPTRUEmailtoadam_at_trachtenb
  erg.com
• DTSTAMP20050530T010553Z
• ENDVEVENT
• ENDVCALENDAR

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iMIP Reply

• BEGINVCALENDAR
• METHODREPLY
• BEGINVEVENT
• SUMMARYPHP 7 Planning and Pub Crawl
• DTSTARTTZIDUS/Pacific20050804T193000
• DTENDTZIDUS/Pacific20050805T020000
• ORGANIZERCN"Michael Radwin"MAILTOmichael_at_radwi
  n.org
• ATTENDEECN"Rasmus Lerdorf"PARTSTATACCEPTEDROL
  EREQ-PARTICIPANTRSVPTRUEmailtorasmus_at_php.net
• DTSTAMP20050705T052030Z
• ENDVEVENT
• ENDVCALENDAR

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Scheduling with CalDAV

• CalDAV is the future
• iMIP still valid for async scheduling

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Time Zones
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How Many Time Zones in the USA?
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What Time is it in Oregon?
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What Time is it in Oregon?
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What Time is it in Indiana?
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What Time is it in Indiana?
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What Time is it in Indiana in 2006?

• Indiana will observe DST next year
• Will spring ahead _at_ 2am on April 2 06
• 77 yellow counties

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Dakotas and Nebraska
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Florida
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Texas
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Dont Worry, Its Not That Bad

• Luckily, you can get free data from the National
  Weather Service
• OST/SEC GIS Map Group
• Time Zones for 3200 counties
• Join with ZIP Code data
• 43,000 ZIPs from Census Bureau

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Other Calendar Formats
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vCalendar 1.0

• The Electronic Calendaring and Scheduling
  Exchange Format
• Published Sep. 1996
• versit Consortium, later Internet Mail Consortium
• File extension .vcs
• Why bother?
• Ancestor of iCalendar
• Still used by legacy apps

• BEGINVCALENDAR
• VERSION1.0
• BEGINVEVENT
• CATEGORIESMEETING
• STATUSTENTATIVE
• DTSTART19960401T033000Z
• DTEND19960401T043000Z
• SUMMARYYour Proposal Review
• DESCRIPTIONSteve and John to review newest
  proposal material
• CLASSPRIVATE
• ENDVEVENT
• ENDVCALENDAR

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Comma Separated Values

• Microsoft proprietary schema for calendar data
• File extension .csv
• Why bother?
• High-fidelity interchange with Outlook
• Why avoid?
• No timezone concept
• Does 6/2/2005 represent June 2nd or February 6th?

• "Subject","Start Date", "Start Time","End
  Date","End Time","All day event","Description","Sh
  ow time as","Location"
• "Project XYZ Review", "11/16/1998","430 PM",
  "11/16/1998","700 PM", "false","","4","Conference
  Room 23A"
• "Bastille Day","7/14/2006", ,,,"true","","3",""

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Palm Date Book Archive

• Palm binary format
• Palm Desktop for Windows only
• Stores dates as POSIX time (seconds since
  midnight Jan 1 1970 UTC)
• File extension .dba
• Why bother?
• Lossless interchange with PalmOS via Windows

• 0001 4244 1064 6566 6175 6c74 5f75 7365
  ..BD.default_use
• 722e 6462 6100 0800 0000 0000 0000 3600
  r.dba.........6.
• 0000 0f00 0000 0000 0000 0100 0000 0200
  ................
• 0000 0f00 0100 0100 0100 0300 0100 0500
  ................
• 0100 0500 0600 0600 0100 0600 0100 0100
  ................
• 0800 f000 0000 0100 0000 0000 0000 0100
  ................
• 0000 0100 0000 0100 0000 ffff ff7f 0300
  ................
• 0000 0c26 f442 0100 0000 442a f442 0500
  ....B....D.B..
• 0000 0000 0000 1b43 616e 646c 6520 6c69
  .......Project X
• 6768 7469 6e67 2028 5061 6c6f 2041 6c74 YZ
  Review (Rm 23
• 6f29 0100 0000 0000 0000 0500 0000 0000
  A)..............
• 0000 0006 0000 0000 0000 0006 0000 0000
  ................
• 0000 0001 0000 0001 0000 0006 0000 0000
  ................
• 0000 0001 0000 00ff ffff ff01 0000 0000
  ................
• 0000 0008 0000 0000 0000 0001 0000 0000
  ................
• 0000 0001 0000 0001 0000 0001 0000 00ff
  ................
• ffff 7f03 0000 00b0 08f5 4201 0000 00b0
  ..........B.....
• 08f5 4205 0000 0000 0000 000e 5061 7261
  ..B.........Bast
• 7368 6174 204d 6173 6569 0100 0000 0000 ille
  Day........

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xCal - iCalendar DTD Document

• iCalendar expressed as XML
• First proposed Aug. 2001
• Internet-Draft expired in Jan. 2003
• File extension .xcs
• Why bother?
• Use XSLT to transform into standard iCalendar
• No loss of data

• ltiCalendargt
• ltvcalendar method"PUBLISH" version"2.0"
• prodid"-//Acme Corp//Example v1.0//EN"gt
• ltveventgt
• ltuidgt15369079-4F9A-4D0A-9ABF-EC5F2F5F1C7Flt/uidgt
  
• ltdtstampgt19981116T145958Zlt/dtstampgt
• ltsummarygtProject XYZ Reviewlt/summarygt
• ltlocationgtConference Room 23Alt/locationgt
• ltdtstartgt19981116T163000Zlt/dtstartgt
• ltdtendgt19981116T190000Zlt/dtendgt
• lt/veventgt
• lt/vcalendargt
• lt/iCalendargt

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RDFiCal, RdfCalendar

• An RDF vocabulary (ontology) for describing
  calendar events based on the iCalendar
• First conceived Oct. 2000 by Tim B-L
• Dan Connolly, Libby Miller still evolving spec
• File extension .rdf
• Why bother?
• Integration with the Semantic Web, FOAF

• ltrdfRDFgt
• ltVcalendargt
• ltversiongt2.0lt/versiongt
• ltprodidgtlt/prodidgt
• ltcomponentgt ltVevent rdfabout"http//www.w3.org
  /uid/A0831EE4-73D1-11D9-B5C3-000393CD78B4"gt
• ltsummarygtProject XYZ Reviewlt/summarygt
• ltdtstart rdfparseType"Resource"gt
• ltdateTimegt2005-01-27T090000lt/dateTimegt
• lt/dtstartgt
• ltduration rdfparseType"Resource"gt
• ltdurationgtPT1H30Mlt/durationgt
• lt/durationgt
• lt/Veventgt lt/componentgt
• lt/Vcalendargt
• lt/rdfRDFgt

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hCalendar

• A 11 representation of iCalendar in XHTML
• First conceived Sep. 2004 by Tantek Çelik
  (Technorati)
• File extension .html
• Why bother?
• HTML makes it easy for bloggers to discuss events
  on their blogs
• Use XSLT to transform into standard iCalendar

• ltspan class"vcalendar"gt
• ltspan class"vevent" id"15369079-4F9A-4D0A-9ABF-
  EC5F2F5F1C7F"gt
• ltspan class"summary"gtAnnual Employee
  Reviewlt/spangt
• ltabbr title"dtstamp" class"19970901T130000Z"gtlt
  /abbrgt
• ltabbr title"dtstart" class"19970903T163000"gtSe
  ptember 3rd, 430pmlt/abbrgt-
• ltabbr title"dtend" class"19970903T190000"gt700
  pm
• lt/abbrgt
• lt/spangt
• lt/spangt

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Calendar Format Recommendations

• Use bona fide iCalendar (RFC 2445)
• Dont choose a wrapper format
• Usually unable to express complex iCalendar
  fields (i.e. RRULE)
• Comma Separated Values (CSV) a valid choice
• Batch export to Microsoft Office Outlook
• Outlook only interprets first VEVENT in .ics file

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Thank you