• asn06

asn06 is an evolving language which RIF-WG is exploring using to describe the elements of a ruleset. It aims to be a subset of OWL, although it may have small formally-defined extensions, and also to be a sort of plain-text UML class diagram. It can also be seen as a data structure interface definition language, or an abstract syntax notation (which is where the name comes from).

The rest of this page is somewhat out-of-date. Some later information is in the thread starting http://lists.w3.org/Archives/Public/public-rif-wg/2007Jan/0121.html

The whole concept was re-articulated as asn07, but the differences are very small. On Jan 30 2007, the WG agreed "RESOLVED: we'll maintain the XML syntax(es) of RIF in the 2-step process, where step one will use asn06 (contingent on asn06 being defined as a subset of OWL Full or some other standard formalism) and step 2 is the precisely specified mapping from asn06 to XML (striped or stripe skipping or whatever). "

asn06 can be used in language design to separate the specification of the semantics from the specification of the concrete syntax. It can also be used to specify multiple semantically-equivalent concrete syntaxes.

Status: This is something SandroHawke hacked together during ISWC2006, chatting with various people, especially HaroldBoley and ChrisWelty, because it looks like the WG needs something like this, and none of the other options seem quite right.

Extending Grammars

One can extend an asn06 grammar by adding one or more class entries which "inherit" from a class in the grammar being extended. Such inheritance adds more options, more disjunctive branches in the grammar.

Example: Abstract Syntax for Purchase Order

Here is the asn06 version of the purchase order example from the XML Schema primer:

  Class PurchaseOrder
     orderDate: string
     shipTo: PersonAtAddress
     billTo: PersonAtAddress
     comment: string
     items: list of item

  Class PersonAtAddress
     name: string
     street: string
     city: string
     state: string
     zip: string

  Class Item 
     partNum: string
     productName: string
     quantity: int
     USPrice: decimal
     comment: string

Abstract Syntax of asn06

Here is the abstract syntax of asn06 written in the normal concrete syntax of asn06.

   Class Class
      name: Identifier
      inherits: Class*
      property: Property*
      sub: Class*
  
   Class Property
      name: Identifier 

      subclass SingleValuedProperty
         type: Identifier

      subclass ListValuedProperty
         elementType: Identifier

      subclass MultiValuedProperty
         type: Identifier
         minCardinality: int
         maxCardinality: int

EBNF for asn06

The concrete syntax for asn06 is inspired by:

• regular expressions and ABNF(for cardinality)
• Algol/Pascal/Modula type declarations
• Python for using indenting to indicate subordinate blocks. (These
  • are handled by the lexer, which provides INDENT and DEDENT acting like "{" and "}" in C-like languages.)
• N3 for URIs and Namespaces

  Grammar ::= NamespaceDeclaration* Class*

  NamespaceDeclaration ::= "prefix" WORD URI

  Identifier ::= WORD | QNAME | URI

  Class ::= "Class"? Identifier 
                ("," "inherits" Identifier)*
                (INDENT Element* DEDENT)?

  Element ::= Identifier ":" Type
            | "subclass"? Class
  
  Type ::= "list" "of" Identifier
         | Identifier Cardinality
            
  Cardinality ::= int? "*" int?    # min and max, defaulting to 0 and inf.
               |  "+"              # min=1, no max
               |  "required"       # min=1, max=1
               |  "optional"       # min=0, max=1
               |                   # nothing?   default maybe needs to be setable

Issues

Terminology: ("rule", "production", "class", ....?) and ("field", "argument", "property", ...?)

How IDs work

default is Optional or Required???