1 Introduction

• this version only describes WSML-Standard, as complement to WSMO-Standard. A version for WSML-Lite and WSML-Full will have to be defined also.
• this version does not describe the concepts of choreography and orchestration, as they are not defined in WSMO-Standard yet. A grounding of a Web Service to a URI is therefore not described yet, as this will be part of the choreography.
• the definition for the qualified names of identifiers has been modelled after the definition in (Biron and Malhotra Eds)(2001). However, it is not yet exactly the same. Future versions of this grammar will follow this definition completely.

2 Example definition

The complete definition of the grammar of WSML-U can be found in section 3. This grammar prescribes how a correct WSMO definition is written using WSML-U. Since the modelling decisions in the grammar (with respect to the resulting language) are not always easily readable, this section will introduce an example definition written in WSML-U. First we will show how to model F-Logic statements using WSML-U, using the same example as in (de Bruijn and Kifer 2004). Then we will model an example web service using an example ontology, from (Arroyo et al. 2004). We model only a part of the example, as the modelling here serves only to explain the use of WSML-U; for an explanation of the use of WSMO (how to completely model this situation where users want to buy tickets and some web service offers that), please see (Arroyo et al. 2004).

Consider the following F-Logic statement, describing an object bob, with a name, an age, an affiliation in some department, of which he is the manager and where he has two assistants:

bob[
	name -> "Bob";
	age -> 40;
	affiliation -> cs1[
		dname -> "CS";
		mngr -> bob;
		assistants -> {john, sally}
	]
]

This example fact is written in WSML-U as follows:

bob[
	name -> "Bob",
	age -> 40,
	affiliation -> cs1[
		dname -> "CS",
		mngr -> bob,
		assistants -> john AND sally
	]
]

As can be seen, the WSML-U syntax is almost equal to Flora-2 syntax. Also note that whitespace and newline characters can be put in at will as they are ignored by the parser (because of the rule WS that `eats' them).

Consider now a web service for buying airline tickets. This web service has one capability, namely to supply requesters with a airline ticket from some location to some other location. This web service uses a specific ontology, in which concepts like flight, location, carrier, etc. are defined. This web service has one interface on which to invoke its capability, which is linked to a WSDL definition. A partial WSML definition of this situation would look like this; modelled after (Arroyo et al. 2004):

WEBSERVICE
	IDENTIFIER <wsnfp-01> END
	NONFUNCTIONALPROPERTIES
		TITLE "Search, book and pay plane ticket" END
		CREATOR "Sinuhe Arroyo" END
		...
	END
	CAPABILITY
		IDENTIFIER <wsnfp-01-capability> END
		PRECONDITION
			origin => X AND destination => T AND departureDate => Y AND 
			arrivalDate => Z AND departureTime => U AND arrivalTime => V 
			AND carrier => W AND seat => R AND class => N AND 
			origin => M AND destionation => S
		END
		PRECONDITION
			validOrigin(X) AND validDestination(T) AND validTrip(X, T) AND 
			validDepartureDate(Y) AND validArrivalDate(Z) AND 
			validTripDates(Y, Z) AND validDepartureTime(U) AND 
			validArrivaltime(V) AND validCarrier(W) AND 
			validSeat(R) AND validTripCarrier(X, T, W)
		END 
		POSTCONDITION
			travelTime => X AND date => Y AND price => Z AND carrier => U 
			AND connections => V AND connectingDestinations => W AND 
			connectingTime => R AND seat => N AND origin => M AND 
			destionation => S AND carrier => C
		END 
		POSTCONDITION
			any(X) AND any(Y) AND any(Z) AND any(U) AND any(V) AND any(W) AND 
			any(R) AND any(N) AND any(M) AND any(S)
		END 
		ASSUMPTION
			arrivalTime => X AND connectingFlight.departureTime => Y AND 
			destination => Z AND connectingFlight.origin => V AND 
			timeConnectingFlight(X, Y) AND spaceConnectingFlight(Z, V) 
			AND carrierConnectingFlight(Z, V, C)
		END 
		EFFECT 
			deliveredTicket
		END 
	INTERFACE
		IDENTIFIER <wsnfp-01-interface1> END
		CHOR (placeholder choreography)
	END
ONTOLOGY
	IDENTIFIER <wsnfp-01-ontology> END
	NONFUNCTIONALPROPERTIES
		TITLE "Plane Itinerary Ontology" END
		CREATOR "Sinuhe Arroyo" END
		...
	END
	CONCEPT
		AXIOM IDENTIFIER <flight> END
		ATTRIBUTE 
			AXIOM IDENTIFIER <origin> END END
			RANGE AXIOM IDENTIFIER <location> END END END
		END
		ATTRIBUTE 
			AXIOM IDENTIFIER <destination> END END
			RANGE AXIOM IDENTIFIER <location> END END END
		END
		...
	END
	CONCEPT
		AXIOM IDENTIFIER <location> END END
		ATTRIBUTE 
			AXIOM IDENTIFIER <name> END END
			RANGE AXIOM IDENTIFIER <string> END END END
		END
		ATTRIBUTE 
			AXIOM IDENTIFIER <airport> END END
			RANGE AXIOM IDENTIFIER <boolean> END END END
		END
	END
	...
END

We can see that the WSML-U definition is clearly less concise than the equivalent F-Logic one. However, the assumption for defining WSML-U is that not all users are comfortable writing F-Logic statements, and would prefer a block-structured syntax even it if means losing conciseness. Since we cannot decide this question by personal favourites, discussion of this grammar is necessary to show whether this is a correct assumption.

3 BNF grammar for WSML-U

wsmoDefinition: (ontologyDefinition | webServiceDefinition | 
	goalDefinition | mediatorDefinition)*	
;

ontologyDefinition: 
	("REFONTOLOGY" Identifier "END") |
	("ONTOLOGY" 
		"IDENTIFIER" Identifier "END"
		(nonFunctionalDefinition)?
		("USEDMEDIATOR" (ooMediatorDefinition)* "END")?
		(axiomDefinition | conceptDefinition | 
		relationDefinition | instanceDefinition)*	
	"END" )
;
	
webServiceDefinition:
	("REFWEBSERVICE" Identifier "END") |
	("WEBSERVICE" 
		"IDENTIFIER" Identifier "END"
		(nonFunctionalWSDefinition)?
		("USEDMEDIATOR" (ooMediatorDefinition)* "END")?
		(capabilityDefinition)?
		(interfaceDefinition)*
	"END")
;
	
goalDefinition:
	("REFGOAL" Identifier "END") |
	("GOAL"
		"IDENTIFIER" Identifier "END"
		(nonFunctionalDefinition)?
		("USEDMEDIATOR" (ooMediatorDefinition | ggMediatorDefinition)* "END")?
		(postConditionDefinition)*
		(effectDefinition)*
	"END")
;

mediatorDefinition:	
	ooMediatorDefinition | ggMediatorDefinition | wgMediatorDefinition | 
	wwMediatorDefinition 
;

ooMediatorDefinition:
	("REFOOMEDIATOR" Identifier "END") | 
	("OOMEDIATOR"
		"IDENTIFIER" Identifier "END"
		(nonFunctionalWSDefinition)?
		("SOURCE" (ontologyDefinition | ooMediatorDefinition) "END")*
		("TARGET" (ontologyDefinition | goalDefinition | 
		webServiceDefinition | mediatorDefinition ) "END")*		
		"MEDIATIONSERVICE" (goalDefinition | wwMediatorDefinition) "END"
	"END")
;
	
ggMediatorDefinition:
	("REFGGMEDIATOR" Identifier "END") |
	("GGMEDIATOR"
		"IDENTIFIER" Identifier "END"
		(nonFunctionalWSDefinition)?
		"SOURCE" (goalDefinition | ggMediatorDefinition) "END"
		"TARGET" (goalDefinition | ggMediatorDefinition) "END"
		("USEDMEDIATOR" (ooMediatorDefinition)* "END")?
		("REDUCTION" axiomDefinition "END")?
	"END")
;

wgMediatorDefinition:
	("REFWGMEDIATOR" Identifier "END") |
	("WGMEDIATOR"
		"IDENTIFIER" Identifier "END"
		(nonFunctionalWSDefinition)?
		"SOURCE" (webServiceDefinition | wgMediatorDefinition) "END"
		"TARGET" (goalDefinition | wgMediatorDefinition) "END"
		("USEDMEDIATOR" (ooMediatorDefinition)* "END")?
		("REDUCTION" axiomDefinition "END")?
	"END")
;
	
wwMediatorDefinition:
	("REFWWMEDIATOR" Identifier "END") |
	("WWMEDIATOR"
		"IDENTIFIER" Identifier "END"
		(nonFunctionalWSDefinition)?
		"SOURCE" (webServiceDefinition | wwMediatorDefinition) "END"
		"TARGET" (webServiceDefinition | wwMediatorDefinition) "END"
		("USEDMEDIATOR" (ooMediatorDefinition)* "END")?
	"END")
;	

axiomDefinition:
	("REFAXIOM" Identifier "END") |
	(
	"IDENTIFIER" Identifier "END"
	(nonFunctionalDefinition)?
	logicalexpression
	)			
;
	
instanceDefinition:
	"INSTANCE"		
		axiomDefinition
		(instanceOfDefinition)*
		(attributeValueDefinition)*
	"END"
;
	
instanceOfDefinition:  "INSTANCEOF" conceptDefinition "END" ;
	
attributeValueDefinition:
	"ATTRIBUTEVALUE"	
		axiomDefinition
		valueDefinition
	"END"
;

valueDefinition:  "VALUE" axiomDefinition "END" ;	

relationDefinition:
	"RELATION"
		axiomDefinition
		(parameterDefinition)*
	"END"
;

parameterDefinition:
	"PARAMETER"
		axiomDefinition
		domainDefinition
	"END"
;

domainDefinition:  "DOMAIN" axiomDefinition "END" ;
	
conceptDefinition:
	("REFCONCEPT" identifier "END") |
	("CONCEPT"			
		axiomDefinition
		(superConceptDefinition)*
		(attributeDefinition)*
		(methodDefinition)*
	"END")
;
	
methodDefinition:
	"METHOD"
		axiomDefinition
		rangeDefinition
		(parameterDefinition)+
	"END"
;

attributeDefinition:
	"ATTRIBUTE"
		axiomDefinition
		rangeDefinition
	"END"
;
	
rangeDefinition:  "RANGE" axiomDefinition "END" ;
	
superConceptDefinition:  "SUPERCONCEPT" conceptDefinition "END" ;
	
capabilityDefinition:
	("REFCAPABILITY" Identifier "END") |
	("CAPABILITY"
		"IDENTIFIER" Identifier "END"
		(nonFunctionalDefinition)?
		("USEDMEDIATOR" (ooMediatorDefinition | wgMediatorDefinition)* "END")?
		(preConditionDefinition | postConditionDefinition | 
		assumptionDefinition | effectDefinition)*
	"END")
;

preConditionDefinition:  "PRECONDITION" axiomDefinition "END" ;
	
postConditionDefinition:  "POSTCONDITION" axiomDefinition "END" ;
	
assumptionDefinition:  "ASSUMPTION" axiomDefinition "END" ;

effectDefinition:  "EFFECT" axiomDefinition "END" ;
	
interfaceDefinition:
	("REFINTERFACE" Identifier "END") |
	("INTERFACE"
		"IDENTIFIER" Identifier "END"
		(nonFunctionalDefinition)?
		("USEDMEDIATOR" (ooMediatorDefinition)* "END")?
		choreographyDefinition
		orchestrationDefinition
	"END")
;
	
choreographyDefinition:  PLACEHOLDERCHOREOGRAPHY ;

orchestrationDefinition:  PLACEHOLDERORCHESTRATION ;
		
nonFunctionalDefinition:
	"NONFUNCTIONALPROPERTIES"		
		nonFunctionalPropertiesList
	"END"
;
	
nonFunctionalPropertiesList:
	("TITLE" String "END")?
	("CREATOR" Identifier "END")?
	("SUBJECT" Identifier "END")*
	("DESCRIPTION" Identifier "END")?
	("PUBLISHER" Identifier "END")?
	("CONTRIBUTOR" Identifier "END")?
	("DATE" Date "END")?
	("TYPE" Identifier "END")?
	("FORMAT" Identifierring "END")?
	("SOURCE" Identifier "END")?
	("LANGUAGE" Identifier "END")?
	("RELATION" Identifier "END")?
	("COVERAGE" Identifier "END")?
	("RIGHTS" Identifier "END")?
	("VERSION" Identifier "END")?
;
	
nonFunctionalWSDefinition:
	"NONFUNCTIONALWSPROPERTIES"
		nonFunctionalPropertiesList		
		("PERFORMANCE" Identifier "END")?
		("RELIABILITY" Identifier "END")?
		("SECURITY" Identifier "END")?
		("SCALABILITY" Identifier "END")?
		("ROBUSTNESS" Identifier "END")?
		("ACCURACY" Identifier "END")?
		("TRANSACTIONAL" Identifier "END")?
		("TRUST" Identifier "END")?
		("FINANCIAL" Identifier "END")?
		("NETWORKRELATEDQOS" Identifier "END")?		
	"END"
;

logicalexpression: rule | fact POINT;
fact: molecule;
existsClause: "EXISTS" PARLEFT VARCONST (COMMA VARCONST)* PARRIGHT;
forallClause: "FORALL" PARLEFT VARCONST (COMMA VARCONST)* PARRIGHT;
rule: ((existsClause)? head)? Implication ((forallClause)? body)?;
head: expr;
body: expr;
expr: molecule ( (AND expr) | (OR expr) )*;

// replaced to avoid left recursion caused e.g. by 'expr: expr (AND expr)?'
// head: conjuct;
// body: conjuct;
// expr: molecule | conjuct | disjunct;
// conjuct: (VARCONST)* expr (AND expr)?;
// disjunct: (VARCONST)* expr (OR expr)?;

molecule: termOrID ((MEMBER | SUBCLASS) term)? 
	(PARLEFT method (COMMA method)* PARRIGHT)? ;
method: term ARROW molecule | 
	CURLYLEFT molecule (COMMA molecule)* CURLYRIGHT ;
termOrID: Identifier | term;
term: String | Integer | VARCONST | reifiedFormula |
	FUNCTOR (PARLEFT term (COMMA term)* PARRIGHT)?;
reifiedFormula: DOLLAR CURLYLEFT expr CURLYRIGHT;

WS:  (' '| '\n' |'\t'|'\r' {newline();}| '\r' {newline();})+ 
	{$setType(Token.SKIP);} ;
ARROW:  "->" | "=>" | "*->" | "*=>" ;
MEMBER:  ":";
SUBCLASS:  "::";
AND:  "AND";
OR:  "OR";
VARCONST:  ('_')? (UpperCaseLetter)* (Letter | Digit)*;
FUNCTOR:  (LowerCaseLetter)* (Letter | Digit)*;
PARLEFT:  '(' ;
PARRIGHT:  ')';
IMPLICATION:  ":-";
BRACKETLEFT:  '[';
BRACKETRIGHT:  ']';
CURLYLEFT: '{';
CURLYRIGHT: '}';
DOLLAR: '$';
COMMA:  ',';
POINT:	'.';

protected Prefix: '<' NCName '>';
protected LocalPart: NCName;
protected NCName: (Letter | '_') (NCNameChar)* ;
protected NCNameChar: Letter | Digit | StrangeCharacters | CombiningChar ;
protected Letter: LowerCaseLetter | UpperCaseLetter;
protected UpperCaseLetter:  'A'..'Z';
protected LowerCaseLetter: 'a'..'z';
protected Digit: '0'..'9';
protected CombiningChar: '/' | '&' | Colon | '?' ;
protected StrangeCharacters: '.' | '-' | '_';
protected Colon: ':';

PLACEHOLDERCHOREOGRAPHY: "CHOR";
PLACEHOLDERORCHESTRATION: "ORCH";

Identifier: '<' (Prefix ':')? LocalPart '>';
String: '\"' (Letter | Digit | '.')+ '\"';
Date: Digit Digit Digit Digit '/' Digit Digit '/' Digit Digit;
Integer: Digit (Digit)*;

4 Acknowledgment

The work is funded by the European Commission under the projects DIP, Knowledge Web, Ontoweb, SEKT, SWWS, Esperonto and h-TechSight; by Science Foundation Ireland under the DERI-Lion project; and by the Vienna city government under the CoOperate program.

The editors would like to thank all the members of the WSMO working group for their advice and input into this document.