ACL & Protocols

by Alan = Mehlenbacher = Oct/2001

Parameters

Parameter

Meaning

1. =

:sender

identity=20 of the sender of the message

2. =

:receiver

identity=20 of the intended recipient of the message.

3. =

:reply-with

expression=20 which will be used by the agent responding to this message to = identify the=20 original message. Can be used to follow a conversation thread in a = situation where multiple dialogues occur = simultaneously.

4. =

:in-reply-to

expression=20 that references an earlier action to which this message is a=20 reply.

5. =

:envelope

expression=20 that provides useful information about the message as seen by the = message=20 transport service -- may include time sent, time received, route,=20 etc.

6. =

:language

encoding=20 scheme of the content of the action.

7. =

:ontology

ontology=20 which is used to give a meaning to the symbols in the content=20 expression.

8. =

:reply-by

time=20 and/or date expression which indicates a guideline on the latest = time by=20 which the sending agent would like a reply.

9. =

:protocol

identifier=20 which denotes the protocol which the sending agent is employing. = The=20 protocol serves to give additional context for the interpretation = of the=20 message.

10. = ;=20

:conversation-id

expression=20 which is used to identify an ongoing sequence of communicative = acts which=20 together form a conversation.

11. = ;=20

:content

content=20 of the message; equivalently denotes the object of the=20 action.

ACL Communicative Acts

ACL=20

Meaning

12. =

accept-proposal

The=20 action of accepting a previously submitted proposal to perform an=20 action.

13. =

agree

The=20 action of agreeing to perform some action, possibly in the=20 future.

14. =

cancel

The=20 action of cancelling some previously requested action which has = temporal=20 extent (i.e. is not instantaneous).

15. =

cfp

The=20 action of calling for proposals to perform a given = action.

16. =

confirm

The=20 sender informs the receiver that a given proposition is true, = where the=20 receiver is known to be uncertain about the = proposition.

17. =

disconfirm

The=20 sender informs the receiver that a given proposition is false, = where the=20 receiver is known to believe, or believe it likely that, the = proposition=20 is true.

18. =

failure

The=20 action of telling another agent that an action was attempted but = the=20 attempt failed.

19. =

inform

The=20 sender informs the receiver that a given proposition is = true.

20. =

inform-if (macro act)

A=20 macro action for the agent of the action to inform the recipient = whether=20 or not a proposition is true.

21. =

inform-ref (macro act)

A=20 macro action for sender to inform the receiver the object which=20 corresponds to a definite descriptor.

22. =

not-understood

The=20 sender of the act A informs the receiver B that it perceived that = B=20 performed some action, but that A did not understand what B just = did. A=20 common case is that A tells B that A did not understand the = message that B=20 has just sent to A.

23. =

propose

The=20 action of submitting a proposal to perform a certain action, given = certain=20 preconditions.

24. =

query-if

The=20 action of asking another agent whether or not a given proposition = is=20 true.

25. =

query-ref

The=20 action of asking another agent for the object referred to by an=20 expression.

26. =

refuse

The=20 action of refusing to perform a given action, and explaining the = reason=20 for the refusal.

27. =

reject-proposal

The=20 action of rejecting a proposal to perform some action during a=20 negotiation.

28. =

request

The=20 sender requests the receiver to perform some action. One important = class=20 of uses of the request act is to request the receiver to perform = another=20 communicative act.

29. =

request-when

The=20 sender wants the receiver to perform some action when some given=20 proposition becomes true.

30. =

request-whenever

The=20 sender wants the receiver to perform some action as soon as some=20 proposition becomes true and thereafter each time the proposition = becomes=20 true again.

31. =

subscribe

The=20 act of requesting a persistent intention to notify the sender of = the value=20 of a reference, and to notify again whenever the object identified = by the=20 reference changes.

Learning=20 ACL by Example query-if,=20 confirm, disconfirm

query-if

The=20 action of asking another agent whether or not a given proposition = is=20 true.

Example

(query-if=20
:sender A:receiver B

:content=20

<marketplace><product>plums</product>

<date>today</date></marketplace>

:language=20 XML

:ontology = mp.xsd)

confirm

The=20 sender informs the receiver that a given proposition is = true.

Example

(confirm=20

:sender=20 B :receiver A

:content=20

<marketplace><product>plums</product>

<date>today</date></marketplace>

:language=20 XML

:ontology = mp.xsd)

disconfirm

The=20 sender informs the receiver that a given proposition is = false.

Example

(disconfirm=20
:sender B:receiver A

:content=20

<marketplace><product>plums</product>

<date>today</date></marketplace>

:language=20 XML

:ontology = mp.xsd)

inform

The=20 sender informs the receiver that a given proposition is = true.

Example

(inform=20
:sender B
:receiver A
:content

<marketplace><product>peaches</product>

<date>today</date></marketplace>
:language = XML

:ontology =20 mp.xsd)

request/failure

request

The=20 sender requests the receiver to perform some action. =

Example

Agent=20 A requests B to open a file:

(request

:sender=20 A
:receiver B
:content=20 = <task><action>open</action><object>\foo.txt\<o= bject>

<purpose>input</purpose></task>

:reply-with=20 of01
:language XML

:ontology = task.xsd)

 agree

The=20 action of agreeing to perform some action.

Example

Agent=20 B answers that it agrees to the request.

(agree=20
:sender B
:receiver A
:content

<purpose>input</purpose></task>

:in-reply-to=20 of01
:language XML

:ontology = task.xsd)

failure

The=20 action of telling another agent that an action was attempted but = the=20 attempt failed.

Example

Agent=20 B informs A that it has failed to open a file:

(failure=20
:sender B
:receiver A
:content

<purpose>input</purpose>=20 <status>error</status>

:in-reply-to=20 of01
:language XML

:ontology =20 task.xsd)

cfp/propose/accept-proposal/reject-proposal

cfp

The=20 action of calling for proposals to perform a given = action.

Example

Agent=20 A asks B to submit its proposal to sell 50 boxes of plums:

(cfp=20
:sender A
:receiver B

:content=20

<unit>box</unit><quantity>50</quantity>&= lt;/proposal>

:conversation-id=20 2000-06-10-384

:language=20 XML

:ontology = bid.xsd)

propose

The=20 action of submitting a proposal to perform a certain action, given = certain=20 preconditions.

Example

Agent=20 B informs A that it will sell 50 boxes of plums for 200:

(propose=20

:sender=20 B

:receiver=20 A

:content=20

:conversation-id=20 2000-06-10-384
:language XML

:ontology = bid.xsd)

 accept-proposal

The=20 action of accepting a proposal to perform an = action.

Example

(accept-proposal=20

:sender=20 A

:receiver=20 B

:content=20

<unit>box</unit><quantity>50</quantity><= /P> <price>200</price></proposal>=20

:conversation-id=20 2000-06-10-384

:language=20 XML

:ontology = bid.xsd)

 reject-proposal

The=20 action of rejecting a proposal to perform some action during a=20 negotiation.

Example

(reject-proposal=20

:sender=20 A

:receiver=20 B
:content

<unit>box</unit><quantity>50</quantity><= /P> <price>200</price></proposal>=20

:conversation-id=20 2000-06-10-384

:language=20 XML

:ontology =20 bid.xsd)

The Rest of the Communicative = Acts

not-understood

The=20 sender received a communicative act which it did not = understand. This would be due to = lack of=20 recognition of the content language, the protocol, or the = ontology.

Example

Agent=20 A did not understand a query-if message because it did not = recognise the=20 ontology:

(not-understood
:sender=20 A

:receiver=20 B

:content

<reason>ontology</reason>

:language=20 xml

:conversation-id=20 200006101030)

refuse

The=20 refuse act is an abbreviation for denying that an act is possible = for the=20 agent to perform, and stating the reason why that is so.

Example

Agent=20 B refuses to sell plums to A, since there are insufficient funds = in A's=20 account:

(refuse=20

:sender=20 B

:receiver=20 A

:content

=20 <reason>insufficient-funds</reason>

:language=20 xml

:conversation-id=20 2000-06-10-384)

cancel

The=20 action of cancelling some previously request'ed action which = has=20 temporal extent (i.e. is not instantaneous) such as an electronic = commerce=20 agreement.

Example

Agent=20 A asks B to cancel an action by cross-referencing the previous=20 conversation in which the request was made:

(cancel=20

:sender=20 A

:receiver=20 B

:conversation-id=20 2000-06-10-384)

inform-if

The=20 inform-if is used like a macro within = a=20 request. The = agent=20 which enacts an inform-if=20 macro-act will actually perform a standard inform act.

Examples

Agent=20 A requests B to inform whether plums are for sale:

(request=20

:sender=20 A

:receiver=20 B

:content=20

= (inform-if=20 :sender B

&n= bsp;=20 :receiver A

&n= bsp;=20 :content =

<product>plums</product>

=20 <status>forsale</status>

:language=20 xml)

:reply-with=20 query1

:language=20 sl)

Agent=20 B replies that they are not:

(inform=20 :sender B
=20 :receiver A
=20 :content

<product>plums</product>

<status>notforsale</status> =

:language = xml

:in-reply-to = query1=20 )

inform-ref

This=20 is similar to inform-if except it wants information about = ("in=20 reference to") some object, e.g. product.

Example

Agent=20 A requests B to tell it what is the product for sale:

(request=20

:sender=20 A

:receiver=20 B

:content=20

(inform-ref =

:sender B

:receiver A

:content

<product>=20 /product>

:language=20 xml)

:reply-with=20 query2

:language=20 sl)

Agent=20 B replies:

(inform=20

:sender=20 B

:receiver=20 A

:content=20

<product>peaches</product>=20

:language=20 xml

:in-reply-to=20 query2)

query-ref

Query-ref is the act of = asking=20 another agent to inform the requestor about the object identified = by a=20 definite descriptor. The sending agent is requesting the receiver = to=20 perform an inform = act,=20 containing the object that corresponds to the definite descriptor = (see=20 also subscribe).

Example

Agent=20 A asks agent B for its products:

(query-ref=20

:sender=20 A

:receiver=20 B

:content=20

=20 <products></products>) =

B=20 replies that it can sell plums & peaches:

(inform=20

:sender=20 B

:receiver=20 A

:content=20

=20 <products>

=20 <product>plums</product>

=20 <product>peaches</product>

=20 </products> )

subscribe

The=20 subscribe act is a = persistent=20 version of query-ref, = such that=20 the agent receiving the subscribe will inform the sender of the = value of=20 the reference, and will continue to send further informs if the object = denoted by=20 the definite description changes.

A=20 subscription set up by a subscribe act is = terminated by a=20 cancel act.

Example

Agent=20 A asks agent B to inform A each time it has products for = sale:

(subscribe

:sender=20 A

:receiver=20 B

:content=20

=20 <products></products>

:language=20 xml

:conversation-id=20 2000-06-11-908)

B=20 replies that it can sell plums::

(inform=20

:sender=20 B

:receiver=20 A

:content=20

=20 <products>

=20 <product>plums</product>

=20 </products>

:language=20 xml

:conversation-id=20 2000-06-11-908 )

B=20 subsequently replies that it can sell peaches and apples:

(inform=20

:sender=20 B

:receiver=20 A

:content=20

=20 <products>

=20 <product>peaches</product>

=20 <product>apples</product>

=20 </products>

:language=20 xml

:conversation-id=20 2000-06-11-908 )

Agent=20 A asks B to cancel the subscribe:

(cancel=20

:sender=20 A

:receiver=20 B

:language=20 xml

:conversation-id=20 2000-06-11-908)

request-when:

Request-when allows an = agent A to=20 inform another agent B that a certain action should be performed = as soon=20 as a given condition becomes true.

Agent=20 B could refuse to do this, or Agent A can cancel it.

Example

Agent=20 A tells agent B to notify it as soon as an auction starts.

(request-when=20

:sender=20 A

:receiver=20 B

:content=20

=20 <message>

(inform=20

:sender=20 B

:receiver=20 A

:content=20

<auction-state>starting</auction-state>)

=20 </message>

=20 <condition>

<auction-state>starting</auction-state>

=20 </condition>

:language=20 xml

:conversation-id=20 2000-06-12-908)

request-whenever

Request-whenever allows = an agent=20 to inform another agent that a certain action should be performed = as soon=20 as a given condition becomes true, and that, furthermore, if the = condition=20 should subsequently become false, the action will be repeated as = soon as=20 it once again becomes true.

Example

Agent=20 A tells agent B to notify it whenever the price of plums goes = under 50.=20

(request-whenever=20

:sender=20 A

:receiver=20 B

:content=20

=20 <message>

(inform=20

:sender=20 B

:receiver=20 A

:content=20 <product>plums</product>

&n= bsp; =20 <price></price>)

=20 </message>

=20 <condition>