Subject: YAML URI scheme rough cut

From: "Clark C . Evans" <[email-masked]>
Date: Fri, 26 Jul 2002 02:22:22 -0400

I want to thank you all, esp Keith Moore, Ted Hardie, and Michael Mealling
for humoring my previous thread.  Its clear to me that although I'm defining
a URN like thingy, it can't be anwhere as strict as RFC 2141 for two reasons,
first the syntax is too restrictive and most importantly each programming
language has it's own mechanism for defining data types, and sometimes these
definitions arn't perfect or up-to-par with the requirements set forth in 
RFC 2141.  Thus, it seems that another scheme is what is needed for YAML,
and rather than trying to find a generic name and buy-in, I figure it would
be better to try and register "yaml" scheme.  So, if you would kindly comment
on this very rough draft, I'd be delighted.

Best,

Clark
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Network Working Group                                           C. Evans
Internet-Draft                                                  YAML.ORG
Expires: January 27, 2003                                  July 26, 2002

                            YAML URI scheme
                         draft-evans-yaml-uri   

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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Copyright Notice

   Copyright (C) The Internet Society (2002). All Rights Reserved.

Abstract

   This draft describes a URI scheme for persistent, transcribable    
   labeling of programming language meta information such as a data
   type, interface or class.  It is envisioned that such a URI would 
   be used in-conjunction with a data serialization mechanism such    
   such as YAML so that type information for a particular data object
   within a particular programming language environment can be 
   serialized along with its content.  

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Table of Contents

   1. Introduction and Background  . . . . . . . . . . . . . . . . . . 3
   2. URI Syntatic Components  . . . . . . . . . . . . . . . . . . . . 3
   3. Character Encoding . . . . . . . . . . . . . . . . . . . . . . . 3
   4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   5. BNF Definition . . . . . . . . . . . . . . . . . . . . . . . . . 4
   6. Environment Semantics  . . . . . . . . . . . . . . . . . . . . . 4
   7. Data Type Semantics  . . . . . . . . . . . . . . . . . . . . . . 4
      References . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
      Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
      Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 6

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1. Introduction and Background

   A core challenge of system integration is moving data objects      
   between systems with either the same or different processing      
   environments.  An emerging trend is to use a textual serialization
   mechanism, such as XML [1] or YAML [2] for this purpose.  When    
   communicating this information beween systems, a unique identifier
   for domain, class or similar data typing information is needed.  
   Currently, there is not a standardized way to accomplish this
   desire and thus interoperability between systems suffers.

   This memo is known to be incomplete and perhaps lack some of the
   background research required to properly define a new URL scheme. 
   Especially the BNF should not be regarded as cast in stone.

2. URI Syntatic Components

   A YAML URI records a composite identification of two components:   
   a processing environment / programming language and a class,       
   protocol, or data type subject to said environment.             

   A YAML URI is a specialization of an absolute opaque URI as  
   defined by RFC 2396 [3].   The general form is written as follows:
                                                                     
   yaml:<environment>,<data-type>
                                                
   Where the environment is unreserved or escaped and the
   data-type matches opaque_part.                

3. Character Encoding                   

   Since many programming languages now allow unicode for their  
   data-type characters, escaping is considered to use Unicode's
   UTF-8 encoding [4].

4. Examples

   This example illustrates a Java(tm) language class name:     
                                                                     
       yaml:java,com.clarkevans.Timesheet.Task

   A Perl language blessed scalar and perl type glob:        

       yaml:perl,$Foo::Bar       yaml:perl,:glob                   
                               
   A language independent (DNS) based type and a private type:
                                    
       yaml:*,clarkevans.com/timesheet
       yaml:-,private+use                                             

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5. BNF Definition               

   Strings are case sensitive and free insertion of
   linear-white-space is not permitted.

   yamluri      = "yaml:" environment "," datatype
                                                    
   environment  = 1*( unreserved | escaped)  ; See RFC 2396 for
                                             ; component definitions

   datatype     = opaque_part                ; Also see RFC 2396
                                                        
   wildtype     = host ?abs_path             ; Also see RFC 2996

6. Environment Semantics                                     

   The environment represents a programming language or processing
   environment.   Usual examples of these would be languages such
   as python, perl, rebol.  Although unreserved characters are 
   allowed, lower case is preferred.  Two special environments are
   defined here, *, for language independent data types, and - for
   private use data types which are local to a specific environment.

7. Data Type Semantics                                           
                                                                   
   The allowed format and semantics of each data type is dependent     
   the particular environment and is beyond the scope of this text.    
   The data type for the * environment should follow wildtype, where
   the host is lower case and no unnecessary escaping is performed.

References

   [1]  Bray, T., et.all  "Extensible Markup Language", 
        http://www.w3.org/TR/2000/REC-xml-20001006

   [2]  Evans, C., Ben-Kiki, O., Ingerson, B.  "YAML Ain't Markup
        Language", http://yaml.org/spec/10jul2002.html

   [3]  Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
        Resource Identifiers (URI): Generic Syntax", RFC 2396, August
        1998.

   [4]  Unicode 3.2  http://www.unicode.org/unicode/reports/tr28/

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Author's Address

   Clark C. Evans 
   630 G ST SE
   Washington, DC 20003
   USA    

   Phone: +1 202.544.7775
   EMail: [email-masked]            

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   Internet Society.

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