Agent Communication Languages Speech act theory Speech act theory Semantics of languages Semantics of languages KQML KQML FIPA ACL FIPA ACL Comparison of FIPA ACL and KQML Comparison of FIPA ACL and KQML Other trends, future work Other trends, future work

Speech acts Example: “Please be quiet!” Example: “Please be quiet!” Locution – the actual performance of the act Locution – the actual performance of the act Illocution – the purpose of the utterance Illocution – the purpose of the utterance Perlocution – the consequences of the utterance Perlocution – the consequences of the utterance

Semantics of languages The process of ascribing meaning The process of ascribing meaning Useful basis: describe the state before sending and after receiving it Useful basis: describe the state before sending and after receiving it Difficult to see if the agent’s state satisfies the pre- and postconditions Difficult to see if the agent’s state satisfies the pre- and postconditions

KQML, introduction Developed under a DARPA funded project, started around 1990 Developed under a DARPA funded project, started around 1990 Language and protocol for exchanging information and knowledge Language and protocol for exchanging information and knowledge Two specifications: Two specifications: –DARPA Knowledge Sharing Initiative 1993 –Yannis Labrou and Tim Finin 1997

KQML, semantics Pre-, post- and completion conditions Pre-, post- and completion conditions Originally it did not assume a full BDI architecture of the agents Originally it did not assume a full BDI architecture of the agents Example Example

KQML, layers Content layer Content layer Message layer Message layer Communication layer Communication layer

KQML, message structure Each message represents a speech act, associated semantics, protocol and a list of attributes Each message represents a speech act, associated semantics, protocol and a list of attributes Example: Example:(performative-name : sender A : receiver B : content X : language L : ontology N : reply-with W : in-reply-to P)

KQML, performatives Describes the type of the message Describes the type of the message About 25 reserved performative names About 25 reserved performative names Additional performatives can be added Additional performatives can be added Special administrative and networking message types Special administrative and networking message types Examples: ask-one Examples: ask-oneadvertisebroadcastinsert

KQML, examples of communication Tell(X) F AB Ask(X) A is aware of B, point-to-point protocol

KQML, examples of communication tell(X) F AB broker(ask(X)) tell(X) advertise(ask(X)) ask(X) Broker performative, ask a facilitator agent to find another agent

FIPA ACL, introduction FIPA, non-profit organization FIPA, non-profit organization Companies like IBM, Hitachi, HP, British Telecom, Siemens Companies like IBM, Hitachi, HP, British Telecom, Siemens Universities and research institutes Universities and research institutes FIPA ACL specified in 1997 FIPA ACL specified in 1997

FIPA ACL, semantics Uses SL, Semantic Language to define the semantics Uses SL, Semantic Language to define the semantics BDI-style primitives BDI-style primitives Feasibility preconditions and rational effect Feasibility preconditions and rational effect Example Example

FIPA ACL, Semantic Language, SL Used to define the semantics of FIPA ACL Used to define the semantics of FIPA ACL Quantified, multi-modal logic with operators for beliefs, desires, uncertain beliefs and intentions Quantified, multi-modal logic with operators for beliefs, desires, uncertain beliefs and intentions Can represent propositions, objects and actions Can represent propositions, objects and actions

FIPA ACL, message structure Syntax almost identical to KQML Syntax almost identical to KQML Each message contains a set of message elements Each message contains a set of message elements Example: Example:(inform :sender I :receiver J :content “weather(today,raining)” :language Prolog :ontology weather42)

Comparison, KQML vs. FIPA ACL Syntactically almost identical Syntactically almost identical FIPA ACL treats register, unregister, etc. as requests for action with reserved meaning FIPA ACL treats register, unregister, etc. as requests for action with reserved meaning No facilitation primitives in FIPA ACL No facilitation primitives in FIPA ACL No commitment to content language in neither of them No commitment to content language in neither of them FIPA ACL more powerful with composing new primitives FIPA ACL more powerful with composing new primitives

Other trends, future work Universal communication language Universal communication language XML – to describe ACL messages XML – to describe ACL messages Common content languages and ontologies Common content languages and ontologies Language for describing agent actions, beliefs, intentions, etc. Language for describing agent actions, beliefs, intentions, etc. Java Java

References FIPA, FIPA, KQML, KQML, Labrou, Finin, Peng, “The current landscape of Agent Communication Languages”, 1999 Labrou, Finin, Peng, “The current landscape of Agent Communication Languages”, 1999

Discussion questions What architectures do the different languages support? What architectures do the different languages support? What kinds of communication do you have in your project? What kinds of communication do you have in your project? What language to use for your project (if any)? What language to use for your project (if any)? What standards do you think are necessary when talking about agent communication languages in the future? What standards do you think are necessary when talking about agent communication languages in the future?