Information Technology Reference
In-Depth Information
3
Environment Modeling
To support multi-party communications and contextual activation, we propose to use the
environment as a privileged intermediary to manage interaction (EASI, Environment as
Active Support for Interaction) and simulation (EASS, Environment as Active Support
for Simulation) process. The EASS model [1] embeds the EASI model [13]. The envi-
ronment manages meta-informations on the MAS (agents, messages, context) and uses
them to compute the agent context(s). In this section, we give the background elements
to understand the assessment of the cost of the environment. More details about the
models can be found in [13].
The environment model E
ASI
is thus defined by
Ω,
D
,P,
F
with:
-
Ω
=
{A∪MSG∪O}
=
{
ω
1
, ..., ω
m
}
the set of entities (with
A
the set of agents,
MSG
the set of messages and
O
the set of objects,
i.e.
all entities that are not
agents or messages),
-
D
=
{
d
1
, ..., d
m
}
the set of domain descriptions of the properties,
-
P
=
{
p
1
, ..., p
n
}
the set of properties,
F
=
{
f
1
, ..., f
k
}
-
the set of filters.
Entity.
An
entity
ω
i
∈ Ω
is defined by
where
e
r
is a reference to an element
of the MAS and
e
d
is the description of that element. An element of the MAS can be
an agent, a message or an object. A reference is its physical address on the platform
or other objects (such as URL, mailbox,
etc.
). The description
e
d
is a set of couples
e
r
,e
d
P
and
v
j
is the value of the property for the entity. Any agent of the
MAS has its own processing and knowledge settings. It is connected to the environment
thanks to its description that the environment stores and updates. This description
e
d
is
used for the routing of the informations to the agent with the reference
e
r
(EASI) or its
activation (EASS). The agents can modify their description dynamically.
p
i
,v
j
where
p
i
∈
Property.
A property
p
i
∈
P
:
Ω
→
d
j
∪{
unknown,null
}
is a function whose
description domain
d
j
∈D
can be quantitative, qualitative or a finite set of data. The
unknown
value is used when the value of the property cannot be set, and
null
is used
to state that the property is undefined in the given description. In order to simplify the
notation, only the value of the description domain
d
j
is given to specify a property.
Filter.
A filter identifies the entities according to their description (
e
d
) and realizes
the interaction between the concrete objects (
e
r
). A filter
f
j
∈F
is a tuple
f
j
=
f
a
,
[
f
m
]
,
[
f
C
]
,n
f
with
n
f
the filter name. The assertion
f
a
:
A→{true,false}
iden-
tifies the related agents, the assertion
f
m
:
MSG → {true,false}
identifies the related
messages, and
f
C
:
P
(
Ω
)
→{true,false}
is an optional set of assertions identifying
other entities of the context. A filter is considered valid for any tuple
agent,
[
message
]
,
[
context
]
such as:
f
a
(
agent
)[
∧f
m
(
message
)][
∧f
C
(
context
)]
is true.
The choice of the action specializes the filter. Every agent
a
whose description validates
f
a
is activated if there exists a set of entities in the
context
such that
f
C
is true. After its
