multiagent systems
a practical approach to
MAS construction in Java
(using Boris)
Simon Lynch [email protected]
software architecture
synchronisation
Language
Engine
Pragmatic
Integration
Speech
Recognition
Working
Kn Base
synchronisation
Speech
Synthesis
Language
Generation
LTM
Kn Base
Dialog
Manager
Expert
System
Wigit
Input
GUI
Models
Visualiser
•distributed
•mixed language
•concurrent
MMD for multiple users
Language
Engine
Pragmatic
Integration
Speech
Recognitio
n
Language
Generation
Speech
Synthesis
Wigit
Input
Working
Kn Base
GUI
Models
Visualiser
LTM
Kn Base
Dialog
Manager
Language
Engine
Pragmatic
Integration
Speech
Recognitio
n
Speech
Synthesis
Language
Generation
•dynamic structure
Wigit
Input
GUI
Models
Visualiser
Expert
System
agents - why?
MultiAgent Systems...
• advanced s/w architectures
(dynamic, distributed...)
• mobility, platform independence
• design-time autonomy
• reuse
agents can also simplify...
• concurrency
• interfacing s/w units
agents – what?
• independent software(?) entities
– send & receive messages
like objects but...
– distributed
– autonomous at design & execution
– have their own process thread
– tighter encapsulation & interfaces
– task oriented
agents – what types?
various types...
• web based, brokered
• small & mobile
• larger scale / intelligent
...etc...
agents - how?
in Java with Boris
analogy...
• agents & GUI components
• GUI events & message events
Boris example
Panel p = new Panel();
Button b = new Button( text );
b.addActionListener( new ActionListener()
{ public void actionPerformed( ActionEvent event )
{ ...code body...
}
});
p.add( b );
Portal p = new Portal( portal-name );
Agent a = new Agent( agent-name );
a.addMessageListener(new MessageListener()
{ public void messageReceived(String from, String to, String msg, MsgId id)
{ ...code body...
}
});
p.addAgent( a );
Sending messages
Portal p = new Portal( portal-name );
Agent sue = new Agent( "sue" );
sue.addMessageListener(new MessageListener()
{ public void messageReceived(String from, String to, String msg, MsgId id)
{ ...code body...
}
});
p.addAgent( sue );
Agent sam = new Agent( "sam" );
p.addAgent( sam );
...
sam.sendMessage( "sue", "hello sue" );
...
Virtual Networks
normally, agents are distributed across
• multiple VMs
• multi-language VMs
• multiple machines
Boris uses network concept based on...
• Portals
• Routers
agents, portals, routers & VMs
agent
agent
agent
agent
agent
MAS design...
a collection of
communicating
agents
agents, portals & routers
agent
agent
portal
agent
agent
agent
portal
agent
router
portal
agent
shared VM
• agents communicate via portals
• portals communicate via router(s)
agents, portals & routers
agent
agent
portal
agent
agent
agent
portal
agent
router
portal
agent
shared VM
• agents who share a portal communicate directly
• routers not necessary for single-portal MASs
agents, portals & routers
agent
agent
portal
agent
agent
agent
portal
agent
router
portal
agent
shared VM
• cross-portal communication requires a router even if
portals share a VM
connecting portals to routers
portal methods
• void connectToGrid(
• void connectToGrid(
• void connectToGrid(
• void connectToGrid(
InetAddress host, int portNo )
int portNo )
InetAddress host )
)
NB:
• connection in separate thread
• may take few seconds over internet
using the console
loading agents
import boris.kernel.*;
.....
public class MyClass
{ public MyClass( Portal portal, String cmdLine )
{
//--- set up agent ---final Agent agent = new Agent( name );
portal.addAgent( agent );
.....
}
.....
}
tracking activity
multiagent systems
clones, replies & sessions
Simon Lynch [email protected]
clones - what
• non-clones have single instances for all
message processing
• clones run multiple instances
• NB:
– timers always run independently
– Java agents are cloneable by default
clones - how
new Agent( name, Agent.NON_CLONEABLE );
new Agent( name, Agent.CLONEABLE );
new Agent( name );
sending replies
Portal p = new Portal( portal-name );
Agent sue = new Agent( "sue" );
sue.addMessageListener(new MessageListener()
{ public void messageReceived(String from, String to, String msg, MsgId id)
{ ...
sue.sendReply( id, "hello" + from );
...
}
});
p.addAgent( sue );
Agent sam = new Agent( "sam" );
p.addAgent( sam );
...
sam.sendMessage( "sue", "hello sue" );
...
MsgId
NB: mostly MsgIds handle themselves, but these
methods are supported...
MsgId
public String getSender()
public String getSessionId()
public boolean expectsReply()
receiving replies - 1
WaitReply sendAndWait( String to, String message )
WaitReply
public String getFrom()
public String getReply()
public MsgId getMfor()
public MsgId getId()
String reply =
sam.sendAndWait( "sue", "hello" ).getReply();
receiving replies - 2
sam.addMessageListener(new MessageListener()
{ public void messageReceived(String from, String to, String msg, MsgId id)
{ ...
sam.sendReply( id, message2 );
...
}
});
ReplyListener rl = new ReplyListener()
{ public void replyReceived( String from, MsgId mfor, String reply, MsgId id )
{ ...
}
};
MsgId mid = sue.sendMessage( "sam", message1 , rl );
boris - additional
timers, scope & brokering
Simon Lynch [email protected]
timers
why, what & how?
1. agent timers
2. countdown timers
3. alarm timers
agent timers
Agent a = new Agent( name );
a.addAgentTimerListener( new AgentTimerListener()
{ public void timerElapsed( Agent a )
{
...code body...
}
});
a.setDelay( delay );
...
a.start();
...
a.stop();
...
the ball example
Agent a = new Agent( "anon" );
a.addAgentTimerListener( new AgentTimerListener()
{
public void timerElapsed( Agent a )
{
erase();
x = (x+dx) % bounds;
y = (y+dy) % bounds;
display();
}
});
a.setDelay( delay );
display();
a.start();
}
a countdown timer
Agent a = new Agent( name );
a.addAgentTimerListener( new AgentTimerListener()
{
public void timerElapsed( Agent a )
{
if( coundown-elapsed )
{
a.stop();
switchOff();
}
else
{
...code body...
}
} });
a.setDelay( delay );
switchOn();
a.start();
alarm timer
given: Calendar alarmTime...
Agent a = new Agent( name );
a.addAgentTimerListener( new AgentTimerListener()
{
public void timerElapsed( Agent a )
{
a.stop();
alarmOn();
} });
long alarmMS = alarmTime.getTime().getTime();
long nowMS = new Date().getTime();
a.setDelay( alarmMS – nowMS );
if (delay > 0 )
a.start();
else
alarmOn();
scope
why, what & how?
•
•
•
•
MAS partitions
holons
reduced complexity
tailored partitions
•
enhanced security
(eg: localised brokers)
scope in Boris
why, what & how?
•
•
•
internal
local
global
- behind portal
- behind router
- the default
scope
agent
agent
portal
agent
agent
agent
portal
agent
router
portal
agent
shared VM
scope in Boris
why, what & how?
portal.addAgent( agent )
portal.addAgent( agent, Portal.INTERNAL )
portal.addAgent( agent, Portal.LOCAL )
Brokers
yellow pages agents
• some are localised (in holons, etc)
• some keep record of providers
• need for central service?
in boris / java
• map agents to services
• services to agents
• etc
starting a router