Microformats Wiki - User contributions [en]

rest/datatypes

2006-01-26T08:19:50Z

ChrisRG: /* Examples */ updated REBOL entry

= Datatypes in HTML =
One of the challenges of using HTML as a data transport is that everything, by default, is a string. This page explores ways to use microformats -- specifically, class names -- to encode data type information, e.g., for use with [[xoxo]] and [[rest/ahah]], in order to allow lossless import/export from various languages. These could also be used with forms to provide [[rest/description]]s of the type of data expected.

== Examples ==

These are the primary datatypes in a range of different languages and formats. Note that we are only concerned with "primitive" datatypes (loosely defined), as structured datatypes (list/array, hash/dictionary) are handled by [[xoxo]].

{| border="1" cellpadding="2"
|+Datatype comparison table
|-
! Language/format !! string !! float !! integer !! boolean !! data || date/time || null
|-
! [http://www.w3.org/TR/xmlschema-2/#built-in-datatypes XML Schema]
| string || float, double || decimal, integer, etc. || boolean || hexBinary, base64Binary || duration, dateTime, date, time || nil
|-
! [http://ws.apache.org/xmlrpc/types.html XML-RPC]
| string || double || i4, int|| boolean || base64 || dateTime.iso8601 || nil
|-
! [http://developer.apple.com/documentation/Cocoa/Conceptual/PropertyLists/Concepts/XMLPListsConcept.html Mac OS X plists]
| string || real || integer || true, false || data || date || nil
|-
! [http://www.crockford.com/JSON JSON] (JavaScript)
| string || number || number || true, false || N/A || Date || nil
|-
! [http://yaml.org/spec/current.html#id2503753 YAML] tags
| str || int || float || bool || null (base 64) || N/A || null
|-
! [http://java.sun.com/j2se/1.3/docs/guide/jdbc/getstart/mapping.html#table1 SQL (JDBC)]
| char,varchar || float, double, real || decimal, numeric || bit || binary || date, time, timestamp || ?
|-
! [http://www.sysprog.net/ctype.html C]
| char[] || float, double || int, long, short || bool, int || char[] || N/A || (void*)0
|-
! [http://java.sun.com/docs/books/tutorial/java/nutsandbolts/datatypes.html Java]
| char, String || float, double || int, long, short, byte || boolean || N/A || util.Date || null
|-
! [http://www.zend.com/manual/language.types.php PHP]
| string || float (double)|| integer || boolean || array || N/A || NULL
|-
! [http://search.cpan.org/dist/perl/pod/perldata.pod Perl]
| array || scalar || scalar || scalar || array || N/A
|-
! [http://en.wikibooks.org/wiki/Programming:Python_Numbers Python]
| str || float, complex || int, long || bool || binascii, base64 || time,datetime
|-
! [http://www.rubycentral.com/book/ext_ruby.html Ruby] + [http://www.rubycentral.com/book/lib_standard.html lib]
| String || Float || Fixnum, Bignum || TrueClass,FalseClass || Hash || Date || NilClass
|-
! [http://www.rebol.com/docs/core23/rebolcore-16.html REBOL]
| string! || decimal! || integer! || logic! || binary! || date!, time! || none!
|-
|}

== Analysis ==
The most common set of datatypes appears to be those represented by XML-RPC, which (perhaps fortunately) also has historical precedence on the web:
* string
* double
* int [i4]
* boolean
* base64
* dateTime[.iso8601]

Whlle not perfect, these certainly cover the 80% case, and are reasonably well-defined. That said, there are a number of open questions about how to use them:
# should 'string' also be explicitly specified, or can it be assumed?
# does 'int' always mean 32-bits?
## If so, what should be used for 64-bit integers or cryptographic (256-bit+) numbers?
###Python's 'long' is simple, but ambiguous.
###Ruby's BigNum is clear but much less common.
###XML-Schema has so many types it is hard to say.
###SQL's "decimal", perhaps?
## If not, how should conforming implementations react to longer integers than they can handle?
# Is it worth deviating from the standard to allow "dateTime" as an alias? (the one case where XML Schema is actually simpler)

== Proposals ==
* TBD

== References ==
* [http://en.wikipedia.org/wiki/Datatype Datatypes] in Wikipedia
* Origional [http://microformats.org/discuss/mail/microformats-discuss/2005-September/001020.html datatype] discussion
* Original [http://homepage.mac.com/drernie/plist.html plist] datatype mapping proposal
* Revised [http://opendarwin.org/~drernie/xoxo-datatypes.html xoxo datatype] proposal

rest/datatypes

2006-01-26T06:55:50Z

ChrisRG: /* Examples */ - Added REBOL datatypes

= Datatypes in HTML =
One of the challenges of using HTML as a data transport is that everything, by default, is a string. This page explores ways to use microformats -- specifically, class names -- to encode data type information, e.g., for use with [[xoxo]] and [[rest/ahah]], in order to allow lossless import/export from various languages. These could also be used with forms to provide [[rest/description]]s of the type of data expected.

== Examples ==

These are the primary datatypes in a range of different languages and formats. Note that we are only concerned with "primitive" datatypes (loosely defined), as structured datatypes (list/array, hash/dictionary) are handled by [[xoxo]].

{| border="1" cellpadding="2"
|+Datatype comparison table
|-
! Language/format !! string !! float !! integer !! boolean !! data || date/time || null
|-
! [http://www.w3.org/TR/xmlschema-2/#built-in-datatypes XML Schema]
| string || float, double || decimal, integer, etc. || boolean || hexBinary, base64Binary || duration, dateTime, date, time || nil
|-
! [http://ws.apache.org/xmlrpc/types.html XML-RPC]
| string || double || i4, int|| boolean || base64 || dateTime.iso8601 || nil
|-
! [http://developer.apple.com/documentation/Cocoa/Conceptual/PropertyLists/Concepts/XMLPListsConcept.html Mac OS X plists]
| string || real || integer || true, false || data || date || nil
|-
! [http://www.crockford.com/JSON JSON] (JavaScript)
| string || number || number || true, false || N/A || Date || nil
|-
! [http://yaml.org/spec/current.html#id2503753 YAML] tags
| str || int || float || bool || null (base 64) || N/A || null
|-
! [http://java.sun.com/j2se/1.3/docs/guide/jdbc/getstart/mapping.html#table1 SQL (JDBC)]
| char,varchar || float, double, real || decimal, numeric || bit || binary || date, time, timestamp || ?
|-
! [http://www.sysprog.net/ctype.html C]
| char[] || float, double || int, long, short || bool, int || char[] || N/A || (void*)0
|-
! [http://java.sun.com/docs/books/tutorial/java/nutsandbolts/datatypes.html Java]
| char, String || float, double || int, long, short, byte || boolean || N/A || util.Date || null
|-
! [http://www.zend.com/manual/language.types.php PHP]
| string || float (double)|| integer || boolean || array || N/A || NULL
|-
! [http://search.cpan.org/dist/perl/pod/perldata.pod Perl]
| array || scalar || scalar || scalar || array || N/A
|-
! [http://en.wikibooks.org/wiki/Programming:Python_Numbers Python]
| str || float, complex || int, long || bool || binascii, base64 || time,datetime
|-
! [http://www.rubycentral.com/book/ext_ruby.html Ruby] + [http://www.rubycentral.com/book/lib_standard.html lib]
| String || Float || Fixnum, Bignum || TrueClass,FalseClass || Hash || Date || NilClass
|-
! [http://www.rebol.com/docs/core23/rebolcore-16.html REBOL]
| string! || decimal! || integer! || logic! || binary! || date! || none!
|-
|}

== Analysis ==
The most common set of datatypes appears to be those represented by XML-RPC, which (perhaps fortunately) also has historical precedence on the web:
* string
* double
* int [i4]
* boolean
* base64
* dateTime[.iso8601]

Whlle not perfect, these certainly cover the 80% case, and are reasonably well-defined. That said, there are a number of open questions about how to use them:
# should 'string' also be explicitly specified, or can it be assumed?
# does 'int' always mean 32-bits?
## If so, what should be used for 64-bit integers or cryptographic (256-bit+) numbers?
###Python's 'long' is simple, but ambiguous.
###Ruby's BigNum is clear but much less common.
###XML-Schema has so many types it is hard to say.
###SQL's "decimal", perhaps?
## If not, how should conforming implementations react to longer integers than they can handle?
# Is it worth deviating from the standard to allow "dateTime" as an alias? (the one case where XML Schema is actually simpler)

== Proposals ==
* TBD

== References ==
* [http://en.wikipedia.org/wiki/Datatype Datatypes] in Wikipedia
* Origional [http://microformats.org/discuss/mail/microformats-discuss/2005-September/001020.html datatype] discussion
* Original [http://homepage.mac.com/drernie/plist.html plist] datatype mapping proposal
* Revised [http://opendarwin.org/~drernie/xoxo-datatypes.html xoxo datatype] proposal