ACAI’01 1

The KNITTER System:KQML for Erlang

Juan A. Suárez RomeroAmparo Alonso BetanzosBertha Guijarro Berdiñas

Laboratory for Research and Development in Artificial Intelligence

Department of Computer Science, University of A Coruña, Spain

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Outline

• Introduction

• KNITTER Architecture

• Summary and Future Work

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Introduction

• To develop a MAS, we need (among others):– Implementation language: Java

• Multiplatform

– Agent communication language: KQML• Independent of implementation language

• Extensible

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Introduction

• Drawbacks– Implementation language: Java

• Inefficient on complex systems

– Agent communication language: KQML• Lack of formal specification interoperability

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Introduction

• Proposal: KNITTER– KQML New Implementation, This Time in

Erlang– Implementation language: Erlang

• Soft real time, multiplatform, concurrent, distributed, ...

– Allows interoperability with other KQML implementations

• Using interchangeable modules

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KNITTER Architecture (I)

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

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KNITTER Architecture (I)

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

Modules are independent

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KNITTER Architecture (I)

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

Some others can be added or changed according with the needs

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KNITTER Architecture (II)Conversation Manager

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

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KNITTER Architecture (II)Conversation Manager

• KQML defines messages, not how to organize it• A conversation allows for a new level of

abstraction• In KNITTER we need to create explicitly a

conversation in order to interoperate with other agent

• There are several forms to define a conversation– Petri Nets, State Automates, etc.

– We may plug-in several types of conversations

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KNITTER Architecture (III)Control Module

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

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KNITTER Architecture (III)Control Module

• The core of the system

• Several functions– Enroutes the messages between conversations

and transport protocols– Creates and activates new conversations– Activates transport protocols– Manages errors

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KNITTER Architecture (IV)Transport Protocol

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

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KNITTER Architecture (IV)Transport Protocol

• Defines the low-level protocol to exchange messages

• Necessary to use the same protocol in order to interoperate

• As conversation managers, it is a plug-in module

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KNITTER Architecture (V)Message Converter

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

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KNITTER Architecture (V)Message Converter

• Defines the low-level message format to use with the transport protocols

• To disengage from transport protocols allow greater flexibility

• As transport protocols, same format is necessary in order to interoperate

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KNITTER Architecture (VI)Agent Name Service

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

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KNITTER Architecture (VI)Agent Name Service

• KQML assigns symbolic names to agents• We need a mapping between this names and

the real information– In which host is agent?– In which port?– Which protocol uses?

• There are several forms to manage this mapping: files, KNS, LDAP, …– We can change the ANS for a more suitable one

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KNITTER Architecture (VII)Utilities

KNITTERCONTROL

Protocol Space

Conversation Space

ConversationManager

Utilities

Agent Name Service (ANS)

ConversationManager

ConversationManager

MessageConverterMessage

ConverterMessageConverter

TransportProtocol

TransportProtocol

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KNITTER Architecture (VII)Utilities

• Several services to users– For example, offers functions to simply manage

the messages

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Summary and Future Work

• We have presented the KNITTER system– Allows the construction of KQML-based agents in

Erlang, a language with interesting features to develop complex multi-agent systems

– Allows the interoperation with other KQML implementations

• KNITTER is still a work in progress– Transport protocols, messages converters, ANS and

conversation managers will be developed to interoperate with other implementations (Jackal)