Transcript Introduction of Java Agent Development Environment (JADE)

Introduction of Java Agent Development Environment (JADE)
余萍
[email protected]
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Introduction
 Foundation for Intelligent Physical Agents (FIPA)
 Java Agent Development Environment (JADE)
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Running JADE Platform
 Install JADE Platform
 Run JADE Platform
 Run Agent on JADE Platform
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IEEE Computer Society standards organization
 A body for developing and setting computer software
standards for heterogeneous and interacting agents and
agent-based systems.
 http://www.fipa.org/
A software agent
 A piece of software that acts for a user or other program in
a relationship of agency
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Agent
Lifecycle Management
Message Transport
Message Structure
Inter-agent Interaction Protocols
Ontologies
Security
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(df-agent-description
:name (agent-identifier
:name [email protected]
:addresses (sequence iiop://foo.com/acc))
:protocols fipa-request
:ontologies (set fipa-agent-management)
:languages (set fipa-sl0)
:lease-time +00000000T600000000T
)
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Agent message transport comprises two
levels:
 (1) The Message Transport Protocol (MTP) carries
out the physical transfer of messages between
two ACCs.
 (2) The Message Transport Service (MTS) is
provided by the AP to which an agent is attached.
The MTS supports the transport of FIPA ACL
messages between agents on any given AP and
between agents on different APs.
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Agent Platform
provides
Normative services
Service
Optional services
Life cycle Management
Agent-Software Integration
White page service
Ontology Service
Yellow page service
Human Agent Interaction
Message Transport service
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JADE is an enabling technology, a
middleware for the development and runtime execution of peer-to-peer applications
which are based on the agents paradigm and
which can seamless work and interoperate
both in wired and wireless environment.
 distributed system topology with peer-to-peer
networking
 software component architecture with agent
paradigm
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FIPA-compliant distributed agent platform
which can be split onto several hosts.
Java Application Programmer’s Interface.
Library of FIPA interaction protocols, such as
Contract Net, ready to be used.
Graphical User Interface to manage several
agents from the same Remote Management
Agent.
Available at http://jade.tilab.com
 Latest version: Jade 4.3 (29/03/2013)
 JADE is free software and is distributed by Telecom Italia
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Mobile Applications
Internet Applications
Corporate Applications
Machine-to-Machine Applications
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Jade Main-container
JRE
Application Agent
host3.us
Application Agent
Application Agent
Application Agent
host2.jp
Application Agent
Application Agent
Application Agent
host1.it
Jade distributed Agent Platform
Jade Agent Container
JRE
Jade Agent Container
JRE
Network protocol stack
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Agent
Management
System
Directory
Facilitator
White page
service
Yellow page
service
Agent Communication Channel
Intra-Container
Message Transport
(Java events)
Inter-Containers
Message Transport
(Java RMI)
cache of
agent addresses
Inter-Platforms
Message Transport
(IIOP, HTTP, …)
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Provides a Yellow Pages service by means of
which an agent can find other agents
providing the services he requires in order to
achieve his goals.
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Provides the naming service
 Ensures that each agent in the platform has a
unique name
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Represents the authority in the platform
 To create/kill agents on remote containers by
requesting that to the AMS
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Provide the GUI to control agents’ lifecycle
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Agent Communication Channel (ACC)
 Agent to Agent
 Agent Platform to Agent Platform
Agent
Management
System
Directory
Facilitator
White page
service
Yellow page
service
Agent Communication Channel
Intra-Container
Message Transport
(Java events)
Inter-Containers
Message Transport
(Java RMI)
cache of
agent addresses
Inter-Platforms
Message Transport
(IIOP, HTTP, …)
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controls the agent’s private queue of ACL messages
designed as a chameleon
 the transport mechanism is selected according to the situation
▪ to achieve the lowest cost for message passing
▪ the overheads depend on the receiver’s location and the cache status
 distributed Agent Communication Channel
 the main container is not a bottle-neck, thanks to the distributed caches
 Message Transport Protocols (MTP) can be activated/deactivated at run-time
on any container via the GUI
▪ IIOP based on the ORB implementation of Sun
▪ IIOP based on the ORBacus implementation
▪ allows to make persistent the object reference
▪ allows a more friendly URL-format corbaloc:iiop:hostname:port/name
▪ HTTP MTP provided by EPFL under LGPL
 multiple ACL encodings have been implemented
▪ String-based, XML-based (EPFL), bit-efficient (Sonera)
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agent is autonomous
 it completely controls its thread of execution
 has a private proxy of the life-cycle manager
 decides itself when to read messages and which messages to read
 the transport mechanism fills a private queue but it does not call the agent
code (no automatic callback)
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agent needs concurrency
 can engage multiple simultaneous conversations
 can execute several concurrent tasks
 Java multi-thread or/and
 JADE behaviours with cooperative scheduling
 one thread-per-agent rather than one thread-per-task/conversation.
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Programming Model
 A JADE agent is mapped onto an user defined Java class, that must subclass
Agent class in jade.core package.
 Agent tasks are mapped onto user defined subclasses of Behaviour class in
jade.core.behaviours package.
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Agents send/receive Java objects, that represent ACLMessages, within
the scope of interaction protocols
 JADE hides all message coding (encoding/parsing)
▪ Envelope level
▪ String-based, XML-based
▪ Agent Communication Language level
▪ String-based, XML-based, bit-efficient
▪ Content Language level
▪ FIPA SL-0 + API to register user-defined content languages
▪ support for Base64-encoded direct Java object serialization
▪ Ontology level
▪ FIPA-Agent Management; JADE Agent Management
▪ API to register user-defined content languages
▪ the framework can be extended by users
▪ all levels provide APIs to implement/register new codecs
▪ work is in progress to improve CL and ontology level extendibility
 JADE provides a library of common interaction protocols
▪ users just need to implement the handle methods
▪ users can compose agent tasks like super-states of FSM
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JADE supports intra-platform mobility and cloning
 A platform can be distributed across multiple hosts
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▪ each host is an agent container
Agents can migrate between containers
Agents can clone across containers
Self-initiated
▪ doMove(Location) / doClone(Location, String)
▪ before/afterMove() before/afterClone()
Requested to the platform (via the AMS)
▪ Fipa-request interaction protocol
▪ jade.domain.MobilityOntology defines all the concepts and actions needed
to support agent mobility and cloning
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RMA (Remote Monitoring Agent)
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to browse the white-page service
to control the agent life-cycle (e.g. remote creation, agent migration, …)
to activate/deactivate MTPs on containers
to browse white-page services of remote agent platforms
DF GUI
 to browse the yellow-page service
 to make DF federations and browse remote DF’s
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DummyAgent
 send/receive store/save ACLMessages
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Sniffer Agent
 to sniff, debug, save to file, multi-agent conversations
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Introspector Agent
 to debug an agent: queue of sent/received messages, queue of behaviours, …
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Configuration of a platform
 from one MAS on a single host
▪ single-host platform
 to one agent on a single host
▪ agent platform on a cluster of hosts
 configuration can be changed at run-time
▪ hot restarting is possible thanks to the local caches
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▪ agent is referred by name => no need to get new reference
Is the main-container a bottle-neck?
 the Agent Communication Channel is distributed
 the main container is involved only when strictly
necessary
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no need to implement the Agent Platform
 AMS, DF, and ACC automatically launched at start-up
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no need to implement agent-management ontology and functionalities
 an agent is registered with the AP by the Java constructor itself
▪ it is given a name and an address
 the Agent class provides a simplified interface to access the services of the DF
(registration, searching, …)
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no need to implement Message Transport and Parsing
 automatically (and possibly efficiently) done by the framework when
sending/receiving messages
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no need to implement Interaction Protocols
 they must only be extended via handle methods
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Book Seller & Book Buyer
Seller1
Buyer
Seller2
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sender of the message
list of receivers
communicative intention (or “performative”)
content
content language
ontology
some fields
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Receiving Messages
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BookSellerAgent extends Agent
 import jade.core.Agent;
 Initial process
▪ Setup()
▪ addBehaviour(new OfferRequestsServer());
▪ addBehaviour(new PurchaseOrdersServer());
 Agent Behaviour
▪ import jade.core.behaviours.*;
▪ PurchaseOrdersServer extends CyclicBehaviour
▪ OfferRequestsServer extends CyclicBehaviour
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Service Registration
• Service Name
• Service Type
Add Behaviour
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Service deregistration
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This abstract class provides an abstract base
class for modelling agent tasks, and it sets
the basis for behaviour scheduling as it allows
for state transitions (i.e. starting, blocking
and restarting a Java behaviour object).
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class SimpleBehaviour
 This abstract class models simple atomic behaviours. Its reset()
method does nothing by default, but it can be overridden by user
defined subclasses.
 class OneShotBehaviour
▪ This abstract class models atomic behaviours that must be executed only once and
cannot be blocked. So, its done() method always returns true.
 class CyclicBehaviour
▪ This abstract class models atomic behaviours that must be executed forever. So its
done() method always returns false.
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class WakerBehaviour
 This abstract class implements a one-shot task
that must be executed only once just after a given
timeout is elapsed.
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class TickerBehaviour
 This abstract class implements a cyclic task that
must be executed periodically.
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class CompositeBehaviour
 This abstract class models behaviours that are made up by
composing a number of other behaviours (children). So the actual
operations performed by executing this behaviour are not defined
in the behaviour itself, but inside its children while the composite
behaviour takes only care of children scheduling according to a
given policy.
 class SequentialBehaviour
▪ This class is a CompositeBehaviour that executes its sub-behaviours sequentially
and terminates when all sub-behaviours are done. Use this class when a complex
task can be expressed as a sequence of atomic steps (e.g. do some computation,
then receive a message, then do some other computation).
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 class ParallelBehaviour
▪ This class is a CompositeBehaviour that executes its sub-behaviours concurrently
and terminates when a particular condition on its sub-behaviours is met. Proper
constants to be indicated in the constructor of this class are provided to create a
ParallelBehaviour that ends when all its sub-behaviours are done, when any one
among its sub-behaviour terminates or when a user defined number N of its subbehaviours have finished. Use this class when a complex task can be expressed as a
collection of parallel alternative operations, with some kind of termination condition
on the spawned subtasks.
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 class FSMBehaviour
▪ This class is a CompositeBehaviour that executes its children according to a Finite
State Machine defined by the user. More in details each child represents the activity
to be performed within a state of the FSM and the user can define the transitions
between the states of the FSM. When the child corresponding to state Si completes,
its termination value (as returned by the onEnd() method) is used to select the
transition to fire and a new state Sj is reached. At next round the child corresponding
to Sj will be executed. Some of the children of an FSMBehaviour can be registered as
final states. The FSMBehaviour terminates after the completion of one of these
children.
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基于Aglets或Jade开发一个电子集市应用，集市中
有三类角色，分别为Manager，Seller，Buyer。其
中，Manager负责对集市中的交易进行管理，Seller
是电子集市中的交易的提供方，Buyer是电子集市
中交易的购买方，可于任意时刻在任何主机上进入
市场，以特定的条件购买特定的商品。Manager负
责调节双方，协助交易的进行。要求：
 Buyer通过迁移进行比价，从报价最便宜的Seller处购买
商品；
 Buyer和Seller通过多次交互完成询价和交易；
 Manager可以帮助Buyer寻找Seller或帮助Seller寻找
Buyer，同时监管所有交易过程。
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