1 Scope
This document is part
of the FIPA specifications covering agent management for inter-operable agents.
This specification incorporates and further enhances [FIPA00002] and
[FIPA00067] represents a companion specification.
This document contains
specifications for agent management including agent management services, agent
management ontology and agent platform message transport, including
the discovery of agents and their offered services in ad hoc[1]
networks..
This document is primarily concerned with defining open standard interfaces for
accessing agent management services. The internal design and implementation of
intelligent agents and agent management infrastructure is not mandated by FIPA
and is outside the scope of this specification.
The document provides a
series of examples to illustrate the agent management functions defined.
2 Agent Management Reference Model
Agent management
provides the normative framework within which FIPA agents exist and operate. It
establishes the logical reference model for the creation, registration,
location, communication, migration and retirement of agents.
The entities contained
in the reference model (see Figure 1) are logical capability sets (that is, services) and do
not imply any physical configuration. Additionally, the implementation details
of individual APs and agents are the design choices of the individual agent
system developers.
Figure 1: Agent
Management Reference Model
The agent management
reference model consists of the following logical components[2],
each representing a capability set (these can be combined in physical
implementations of APs):
·
An agent is a computational process that implements the
autonomous, communicating functionality of an application. Agents communicate
using an Agent Communication Language. An Agent is the fundamental actor on an
AP which combines one or more service capabilities, as published in a service
description, into a unified and integrated execution model. An agent must have
at least one owner, for example, based on organisational affiliation or human
user ownership, and an agent must support at least one notion of identity. This
notion of identity is the Agent Identifier (AID) that labels an agent so that
it may be distinguished unambiguously within the Agent Universe. An agent may
be registered at a number of transport addresses at which it can be contacted.
·
A Directory
Facilitator (DF) is an optional
component of the AP, but if it is present, it must be implemented as a DF
service (see Section 4.1). The DF provides yellow pages services to other
agents. Agents may register their services with the DF or query the DF to find
out what services are offered by other agents,
including the discovery of agents
and their offered services in ad hoc networks. Multiple DFs may exist within an AP and may be federated.
The DF is a reification of the Agent Directory Service in [FIPA00001].
·
An Agent
Management System (AMS) is a
mandatory component of the AP. The AMS exerts supervisory control over access
to and use of the AP. Only one AMS will exist in a single AP. The AMS maintains
a directory of AIDs which contain transport addresses (amongst other things)
for agents registered with the AP. The AMS offers white pages services to other
agents. Each agent must register with an AMS in order to get a valid AID. The
AMS is a reification of the Agent Directory Service in [FIPA00001].
·
An Message
Transport Service (MTS) is the
default communication method between agents on different APs (see [FIPA00067]).
·
An Agent
Platform (AP) provides the
physical infrastructure in which agents can be deployed. The AP consists of the
machine(s), operating system, agent support software, FIPA agent management
components (DF, AMS and MTS) and agents.
The internal design of an AP is an issue for agent system developers and
is not a subject of standardisation within FIPA. AP’s and the agents which are
native to those APs, either by creation directly within or migration to the AP,
may use any proprietary method of inter-communication.
It should be noted that the concept of an AP does not mean that all
agents resident on an AP have to be co-located on the same host computer. FIPA
envisages a variety of different APs from single processes containing
lightweight agent threads, to fully distributed APs built around proprietary or
open middleware standards.
FIPA is concerned only with how communication is carried out between
agents who are native to the AP and agents outside the AP. Agents are free to
exchange messages directly by any means that they can support.
·
Software describes all non-agent, executable collections
of instructions accessible through an agent. Agents may access software, for
example, to add new services, acquire new communications protocols, acquire new
security protocols/algorithms, acquire new negotiation protocols, access tools
which support migration, etc.
3
Agent Naming
The FIPA agent naming reference model identifies an agent through an extensible collection of parameter-value pairs[3], called an Agent Identifier (AID). The extensible nature of an AID allows it to be augmented to accommodate other requirements, such as social names, nick names, roles, etc. which can then be attached to services within the AP. An AID comprises[4] (see Section 6.1.1):
·
The name parameter, which is a globally unique identifier that can
be used as a unique referring expression of the agent. One of the simplest
mechanisms is to construct it from the actual name of the agent and its home
agent platform address[5]
(HAP), separated by the @ character. This is a
reification of the notion of an Agent Name from [FIPA00001].
· The addresses parameter, which is a list of transport addresses where a message can be delivered (see Section 3.1). This is a reification of the notion of a Locator from [FIPA00001].
· The resolvers parameter, which is a list of name resolution service addresses (see Section 3.2).
The parameter values of an AID can be edited or modified by an agent, for example, to update the sequence of name resolution servers or transport addresses in an AID. However, the mandatory parameters can only be changed by the agent to whom the AID belongs. AIDs are primarily intended to be used to identify agents inside the envelope of a transport message, specifically within the to and from parameters (see [FIPA00067]).
Two AIDs are considered
to be equivalent if their name parameters are
the same.
3.1 Transport Addresses
A transport address is
a physical address at which an agent can be contacted and is usually specific
to a Message Transport Protocol. A given agent may support many methods of
communication and can put multiple transport address values in the addresses parameter of an AID.
The EBNF syntax of a
transport addresses is the same as for a URL given in [RFC2396]. [FIPA00067] describes the semantics of
message delivery with regard to transport addresses.
3.2 Name Resolution
Name resolution is a service that is provided by the AMS
through the search function. The resolvers parameter of
the AID contains a sequence of AIDs at which the AID of the agent can
ultimately be resolved into a transport address or set of transport address.
An example name resolution pattern might be:
1.
agent-a wishes to send a message to agent-b, whose AID is:
(agent-identifier
:name agent-b@bar.com
:resolvers (sequence
(agent-identifier
:name ams@foo.com
:addresses (sequence
iiop://foo.com/acc))))
and
agent-a wishes to know
additional transport addresses that have been given for agent-b.
2.
Therefore, agent-a can send a search request to the
first agent specified in the resolvers parameter which is typically an AMS. In this
example, the AMS at foo.com.
3.
If the AMS at foo.com has agent-b
registered with it, then it
returns a result message containing the AMS agent description of
agent-b; if not, then a failed message is
returned.
4.
Upon receipt of
the result message, agent-a can extract the agent-identifier parameter of the ams-agent-description
and then extract the addresses parameter of this to determine the transport
address(es) of agent-b.
5.
agent-a can now send a message to agent-b by inserting the addresses parameter
into the AID of agent-b.
4 Agent Management Services
4.1 Directory Facilitator
4.1.1
Overview
A DF is a component of
an AP that provides a yellow pages directory service to agents; . It is the trusted, benign
custodian of the agent directory. It is trusted in the sense that it must
strive to maintain an accurate, complete and timely list of agents. It is
benign in the sense that it must provide the most current information about
agents in its directory on a non-discriminatory basis to all authorised agents.
The DF is an optional component of an AP. At least one DF must be resident on each AP (the
default DF). However, an AP may support any number of DFs and DFs
may register with each other to form federations.
Every agent that wishes
to publicise its services to other agents, should find an appropriate DF and
request the registration of
its agent description. There is no intended future commitment or obligation on
the part of the registering agent implied in the act of registering. For
example, an agent can refuse a request for a service which is advertised
through a DF. Additionally, the DF cannot guarantee the validity or accuracy of
the information that has been registered with it, neither can it control the
life cycle of any agent. An object description must be supplied containing
values for all of the mandatory parameters of the description. It may also
supply optional and private parameters, containing non-FIPA standardised
information that an agent developer might want included in the directory. The deregistration function has the consequence that there is no
longer a commitment on behalf of the DF to broker information relating to that
agent. At any time, and for any reason, the agent may request the DF to modify its agent description.
An agent may search in order to request information from a DF. The
DF does not guarantee the validity of the information provided in response to a
search request, since the DF does not place any restrictions on the information
that can be registered with it. However, the DF may restrict access to
information in its directory and will verify all access permissions for agents
which attempt to inform it of agent state changes. A DF may also decide to restrict
the visibility of the registered agent descriptions according to a certain
policy. How such a policy is specified is currently outside the scope of this
document.
The default DF
on an AP, if present, has a reserved AID of:
(agent-identifier
:name df@hap_name[6]
:addresses (sequence hap_transport_address))
The DF also
provides discovery functionality in ad hoc networks, in which network nodes may frequently join and leave. It provides a
high-level interface for agents therebythat hides the possible usage of various discovery
middleware (DM), depending on the underlying ad hoc technology. Figure 2
outlines a possible model of a DF wrapping various DMs. Figure 1 outlines a possible model of a DF wrapping various
discovery middlewares.
Figure 1: Reference Model of the Discovery Process in Ad Hoc
Networks
4.1.2 Management Functions Supported by the Directory Facilitator
In order to access the
directory of agent descriptions managed by the DF, each DF must be able to
perform the following functions, when defined on the domain of objects of type df-agent-description in compliance with the semantics described in Section
6.1.2:
·
register
·
deregister
·
modify
·
search
ThThee fipa-request
interaction protocol [FIPA00026] must be
used by agents wishing to request a DF to perform these actions.
A DF may
support the following extended directory mechanism:
·
subscribe
mechanism
For the subscribe
mechanism a DF must implement the fipa-subscribe interaction protocol [FIPA00035]
in order to allow agents to subscribe for being notified about registration, deregistration and
modifications of certain agent descriptions. If implemented, the implementation
of this protocol must comply with the semantics and syntax specified in section
4.1.4.
get thea DF may support an
introspection functionality. In order to get that information an agent may ask
the DF for its df-agent-description (the agent description of the
DF). The df-agent-description contains beside other
information a services
slot which can contain a set of service descriptions. Each of the service descriptions may contain information such as the ability of the DF to publish and
search offered agent services in underlaying DMs (see type slot in section 6.1.3)[7]The
fipa-request interaction protocol [FIPA00026] must be used by
agents wishing to request a DF to perform this action and receive the list of available DMs.[8] A
DF that does not support such functionality is simply required to respond with a refuse communicative act with unsupported-function as content of the communicative act.
4.1.3 Federated Directory Facilitators
The DF encompasses a
search mechanism that searches first locally and then extends the search to
other DFs, if allowed. The default search mechanism is assumed to be a
depth-first search across DFs. For specific purposes, optional constraints can
be used as described in Section 06.1.4 such
as the number of answers (max-results). The
federation of DFs for extending searches can be achieved by DFs registering
with each other with fipa-df as the value
of the type parameter in the service-description.
When a DF receives a
search action, it may determine whether it needs to propagate this search to
other DFs that are registered with it[9].
It should only forward searches where the value of the max-depth parameter is greater than 1 and where it has not received
a prior search with the same search-id parameter.
If it does forward the search action, then it must use the following rules:
1. It must not change the value of the search-id parameter when it propagates the search and the value of all search-id parameters should be globally unique.
2. Before propagation, it should decrement the value of the max-depth parameter by 1.
4.1.4 Subscribing and Unsubscribing with the DF
Some DFs may implement the fipa-subscribe interaction protocol [FIPA00035] in order to allow
agents to subscribe for being
notified about registration,
deregistration and modifications of the registeredcertain agent descriptions.
A DF that does not support such a functionality is
simply required to respond with a not-understood communicative act with unsupported-act
as content
of the communicative act
(see also 6.4.3 6.3.3).
Further to what specified in [FIPA00035], the usage of the fipa-subscribe interaction protocol must obey to the following
rules:
-
the content
of the subscribe communicative act must be a referential expression denoting a persistent search action. For
simplicity, the following can be used
"(
(action
(agent-identifier
:name df@foo.com
:addresses (sequence
iiop://foo.com/acc)
)
(search
(df-agent-description
:ontologies (set
meeting-scheduler)
:languages (set fipa-sl0 kif)
:services (set
(service-description
:name profiling
:type
meeting-scheduler-service))
)
(search-constraints :max-depth 2)))
)"
to
denote (and be understood as):
"((iota ?x
(result
(action
(agent-identifier
:name df@foo.com
:addresses
(sequence iiop://foo.com/acc)
)
(search
(df-agent-description
:ontologies (set meeting-scheduler)
:languages (set fipa-sl0 kif)
:services (set
(service-description
:name profiling
:type meeting-scheduler-service))
)
(search-constraints :max-depth 2)))
?x)))"
-
the DF must
continue to send an inform
communicative act as the objects denoted by the referring expression
change, i.e. as the result of the persistent search
changes. For
simplicity, the following can be used:
"((result
(action
(agent-identifier
:name df@foo.com
:addresses
(sequence iiop://foo.com/acc))
(search
(df-agent-description
:ontologies (set
meeting-scheduler)
:languages
(set fipa-sl0 kif)
:services
(set
(service-description
:name profiling
:type meeting-scheduler-service))
(search-constraints :max-depth 2))))
(set
(df-agent-description
:name
(agent-identifier
:name scheduler-agent@foo.com
:addresses (sequence iiop://foo.com/acc))
:ontologies (set meeting-scheduler fipa-agent-management)
:languages (set fipa-sl0 fipa-sl1 kif)
:services (set
(service-description
:name profiling
:type meeting-scheduler-service)
(service-description
:name profiling
:type user-profiling-service))))))")
to denote (and be understood as):
"(= (iota ?x
(result
(action
(agent-identifier
:name df@foo.com
:addresses (sequence
iiop://foo.com/acc)
)
(search
(df-agent-description
:ontologies (set
meeting-scheduler)
:languages (set fipa-sl0 kif)
:services (set
(service-description
:name profiling
:type
meeting-scheduler-service))
)
(search-constraints :max-depth 2)))
?x))
(set
(df-agent-description
:name
(agent-identifier
:name scheduler-agent@foo.com
:addresses (sequence iiop://foo.com/acc))
:ontologies (set meeting-scheduler fipa-agent-management)
:languages (set fipa-sl0 fipa-sl1 kif)
:services (set
(service-description
:name profiling
:type meeting-scheduler-service)
(service-description
:name profiling
:type user-profiling-service)))))"
A
subscription is terminated by a cancel act as specified in [FIPA0003535].
4.2 Agent Management System
4.2.1 Overview
An AMS is a mandatory
component of the AP and only one AMS will exist in a single AP. The AMS is
responsible for managing the operation of an AP, such as the creation of
agents, the deletion of agents and overseeing the migration of agents to and
from the AP (if agent mobility is supported by the AP). Since different APs
have different capabilities, the AMS can be queried to obtain a description of
its AP. A life cycle is associated with each agent on the AP (see Section 5.1)
which is maintained by the AMS.
The AMS represents the
managing authority of an AP and if the AP spans multiple machines, then the AMS
represents the authority across all machines. An AMS can request that an agent
performs a specific management function, such as quit (that is, terminate all execution on its AP) and has the
authority to forcibly enforce the function if such a request is ignored.
The AMS maintains an
index of all the agents that are currently resident on an AP, which includes
the AID of agents. Residency of an agent on the AP implies that the agent has
been registered with the AMS. Each agent, in order to comply with the FIPA
reference model, must register
with the AMS of its HAP.
Agent descriptions can
be later modified at any
time and for any reason. Modification is restricted by authorisation of the
AMS. The life of an agent with an AP terminates with its deregistration from the AMS. After deregistration, the AID of
that agent can be removed by the directory and can be made available to other
agents who should request it.
Agent description can
be searched with the AMS and
access to the directory of ams-agent-descriptions
is further controlled by the AMS; no default policy is specified by this
specification. The AMS is also the custodian of the AP description that can be
retrieved by requesting the action get-description.
The AMS on an AP has a
reserved AID of:
(agent-identifier
:name ams@hap_name[10]
:addresses (sequence hap_transport_address))
The name parameter of the AMS (ams@hap_name) is considered to be the Service Root of the AP
(see [FIPA00001]).
4.2.2 Management Functions Supported by the Agent
Management System
An AMS must be able to
perform the following functions, in compliance with the semantics described in
Section 06.1.5 (the first four functions are defined within the
scope of the AMS, only on the domain of objects of type ams-agent-description and the last on the domain of objects of type ap-description):
·
register
·
deregister
·
modify
·
search
·
get-description
In addition to the
management functions exchanged between the AMS and agents on the AP, the AMS
can instruct the underlying AP to perform the following operations:
·
Suspend agent,
·
Terminate agent,
·
Create agent,
·
Resume agent
execution,
·
Invoke agent,
·
Execute agent,
and,
·
Resource
management.
4.3 Message Transport Service
The Message Transport
Service (MTS) delivers messages between agents within an AP and to agents that
are resident on other APs. All FIPA agents have access to at least one MTS and
only messages addressed to an agent can be sent to the MTS. See [FIPA00067] for more information on the
MTS.
5 Agent Platform
5.1 Agent Life Cycle
FIPA agents exist
physically on an AP and utilise the facilities offered by the AP for realising
their functionalities. In this context, an agent, as a physical software
process, has a physical life cycle that has to be managed by the AP. This section describes a possible life cycle that can be used to
describe the states which it is believed are necessary and the responsibilities
of the AMS in these states.
The life cycle of a
FIPA agent is (see Figure 23):
·
AP Bounded
An agent is physically managed within an AP and the life cycle of a
static agent is therefore always bounded to a specific AP.
·
Application
Independent
The life cycle model is independent from any application system and it
defines only the states and the transitions of the agent service in its life
cycle.
·
Instance-Oriented
The agent described in the life cycle model is assumed to be an instance
(that is, an agent which has unique name and is executed independently).
·
Unique
Each agent has only one AP life cycle state at any time and within only
one AP.
Figure 23: Agent Life Cycle
The followings are the
responsibility that an AMS, on behalf of the AP, has with regard to message
delivery in each state of the life cycle of an agent:
·
Active
The MTS delivers messages to the agent as normal.
·
Initiated/Waiting/Suspended
The MTS either buffers messages until the agent returns to the active
state or forwards messages to a new location (if a forward is set for the
agent).
·
Transit
The MTS either buffers messages until the agent becomes active (that is,
the move function failed on the original AP or the agent was successfully
started on the destination AP) or forwards messages to a new location (if a
forward is set for the agent). Notice that only mobile agents can enter the Transit
state. This ensures that a
stationary agent executes all of its instructions on the node where it was
invoked.
·
Unknown
The MTS either buffers messages or rejects them, depending upon the
policy of the MTS and the transport requirements of the
message.
The state transitions
of agents can be described as:
·
Create
The creation or installation of a new agent.
·
Invoke
The invocation of a new agent.
·
Destroy
The forceful termination of an agent. This can only be initiated by the
AMS and cannot be ignored by the agent.
·
Quit
The graceful termination of an agent. This can be ignored by the agent.
·
Suspend
Puts an agent in a suspended state. This can be initiated by the agent
or the AMS.
·
Resume
Brings the agent from a suspended state. This can only be initiated by
the AMS.
·
Wait
Puts an agent in
a waiting state. This can only be initiated by an
agent.
·
Wake Up
Brings the agent from a waiting state. This can only be initiated by the
AMS.
The following two
transitions are only used by mobile agents:
·
Move
Puts the agent in a transitory state. This can only be initiated by the
agent.
·
Execute
Brings the agent from a transitory state. This can only be initiated by
the AMS.
5.2 Agent Registration
There are three ways in
which an agent can be registered with an AMS:
·
The agent was
created on the AP.
·
The agent migrated
to the AP, for those APs which support agent mobility.
·
The agent
explicitly registered with the AP.
Agent registration
involves registering an AID with the AMS. When an agent is either created or
registers with an AP, the agent is registered with the AMS, for example by
using the register function. In the following example, an agent
called discovery-agent is
registering with an AP located at foo.com. The
agent discovery-agent was
created on the AP (that is, discovery-agent’s HAP) at bar.com and requests
that the AMS registers it.
For example:
:sender
(agent-identifier
:name
discovery-agent@bar.com
:addresses (sequence
iiop://bar.com/acc))
:receiver (set
(agent-identifier
:name ams@foo.com
:addresses (sequence
iiop://foo.com/acc)))
:ontology
fipa-agent-management
:language fipa-sl0
:protocol fipa-request
:content
"((action
(agent-identifier
:name ams@foo.com
:addresses (sequence
iiop://foo.com/acc))
(register
(:ams-description
:name
(agent-identifier
:name discovery-agent@bar.com
:addresses (sequence iiop://bar.com/acc))
...)))")
It should be noted that
the addresses parameter of the AID represents the transport
address(es) that the agent would like any messages directed to (see [FIPA00067] for information on how the MTS
deals with this). In the above example, the agent discovery-agent registers itself with the foo.com AP but by virtue of specifying a different transport
address in the addresses parameter of its AID, messages that arrive at foo.com will be forwarded to bar.com.
5.2.1 Registration Lease Times
To enable the DF to
manage a maintainable number of registrations over a long period of time, the
DF may implement lease times using the lease-time parameter of a df-agent-description. A lease time is either a duration of time, such as 3
hours, or an absolute time, such as 08:00 26-Jul-2002, at which point a
registration made by an agent can be removed from the DF registration database.
When an agent wishes to
register with a DF, it can specify a lease time which is how long it would like
the registration to be kept. If this lease time is okay for the DF, then it
will accept the registration as usual and the value of the lease-time parameter in the content of the inform reply will be the same. Consequently, when the
lease time expires, the registration will be silently removed by the DF. On the
other hand, if the lease time is not acceptable to the DF, then the DF can
include a new lease time as
the value of the lease-time parameter in the content of the inform reply. This is the case when an agent does not
specify a lease time in its registration.
If the DF does not
support lease times, it will notify to the requesting agent that its
registration is valid for an unlimited time by removing this parameter in the
content of the inform reply, in fact the default lease-time is
defined to be unlimited.
For example, and agent
may register the following df-agent-description:
(request
...
:content
"((action
(agent-identifier
:name df@foo.com
:addresses (sequence iiop://foo.com/acc))
(register
(df-agent-description
:name
(agent-identifier
:name dummy@foo.com
:addresses (sequence iiop://foo.com/acc))
:protocols
fipa-request
:ontologies (set fipa-agent-management)
:languages
(set fipa-sl0)
:lease-time
+00000000T600000000T
...")
Then if the DF agrees
to this lease time, it will reply with and inform which contains the same value
for the lease-time parameter:
(inform
...
:content
"((done
(action
(agent-identifier
:name df@foo.com
:addresses
(sequence iiop://foo.com/acc))
(register
(df-agent-description
:name
(agent-identifier
:name dummy@foo.com
:addresses (sequence iiop://foo.com/acc))
:protocols
(set fipa-request application-protocol)
:ontologies
(set meeting-scheduler)
:languages
(set fipa-sl0 kif)
:lease-time +00000000T600000000T
...")
If an agent wishes to renew a lease time,
then it can use the modify action to specify a new value for the lease-time parameter. The
verification of this lease time goes through the same procedure mentioned in
the last paragraph: if it is okay, then the value of
the lease-time parameter in the content of the inform reply will be the same, if it is not okay, the
value of the lease-time parameter in the content of the inform reply will be a new value which is acceptable
to the DF.
6 Agent Management Ontology
6.1 Object Descriptions
This section describes a set of frames that represent the classes of objects in the domain of discourse within the framework of the fipa-agent-management ontology. The closure of symbols of this ontology can be obtained from [FIPA00067] that specifies additional set of frames of this ontology.
This ontology does not specify any specific positional order to encode the parameters of the objects. Therefore, it is required to encode objects in SL by specifying both the parameter name and the parameter value (see Section 3.6 of [FIPA00008]).
The following terms are used to describe the objects of the domain:
· Frame. This is the mandatory name of this entity that must be used to represent each instance of this class.
· Ontology. This is the name of the ontology, whose domain of discourse includes the parameters described in the table.
· Parameter. This is the mandatory name of a parameter of this frame.
· Description. This is a natural language description of the semantics of each parameter.
· Presence. This indicates whether each parameter is mandatory or optional.
· Type. This is the type of the values of the parameter: Integer, Word, String, URL, Term, Set or Sequence.
· Reserved Values. This is a list of FIPA-defined constants that can assume values for this parameter.
6.1.1 Agent Identifier Description
This type of object represents the identification of the agent. The addresses parameter and the name resolution mechanism (see Section 3.2), is a reification of the notion of Locator from [FIPA00001]. See also Section 3.3.7 in FIPA Agent Message Transport Service [FIPA00067] specifications.
|
Frame Ontology |
agent-identifier fipa-agent-management |
|
||
|
Parameter |
Description |
Presence |
Type |
Reserved Values |
|
name |
The symbolic name of the agent. |
Mandatory |
word |
df@hap_name ams@hap_name |
|
addresses |
A sequence of ordered transport addresses where the agent can be contacted. The order implies a preference relation of the agent to receive messages over that address. |
Optional |
Sequence of url |
|
|
resolvers |
A sequence of ordered AIDs where name resolution services for the agent can be contacted. The order in the sequence implies a preference in the list of resolvers. |
Optional |
Sequence of agent-identifier |
|
6.1.2 Directory Facilitator Agent Description
This type of object represents the description that can be registered with the DF service. This is a reification of the Agent Directory Entry from [FIPA00001].
|
Frame Ontology |
df-agent-description fipa-agent-management |
|
||
|
Parameter |
Description |
Presence |
Type |
Reserved
Values |
|
name |
The identifier of the agent. |
Optional |
agent-identifier[11] |
|
|
services |
A list of services supported by this agent. |
Optional |
Set of service-description |
|
|
protocols |
A list of interaction protocols supported by the agent. |
Optional |
Set of string |
See [FIPA00025] |
|
ontologies |
A list of ontologies known by the agent. |
Optional |
Set of string |
fipa-agent-management |
|
languages |
A list of content languages known by the agent. |
Optional |
Set of string |
fipa-sl fipa-sl0 fipa-sl1 fipa-sl2 |
|
lease-time |
The duration or time at which the lease for this registration will expire[12]. |
Optional |
datetime[13] |
|
|
scope |
This parameter defines the visibility of this
df-agent-description. The default value is global, meaning
that the agent does not wish to put any restriction to
the visibility of the registered df-agent-description. The value ‘local’ means that the registered df-agent-description
must not be
visible and
returned as a result of a search propagated by a federated DF. |
Optional |
Set of string |
global local
|
|
|
|
|
|
|
Note: The scope slot is an extension to the first version [SC000023] of this standard. Existing DFs, that are compatible with the previous version of the specs, are also compatible with this version of the spec with the only exception that they will not be able to enforce a scope different from ‘global’.
6.1.3 Service Description
This type of object represents the description of each service registered with the DF.
|
Frame Ontology |
service-description fipa-agent-management |
|
||
|
Parameter |
Description |
Presence |
Type |
Reserved
Values |
|
n |
The name of the service. |
Optional |
string |
|
|
t |
The type of the service. |
Optional |
string |
fipa-df[17] fipa-ams
|
|
protocols |
A list of interaction protocols supported by the service. |
Optional |
Set of string |
|
|
ontologies |
A list of ontologies supported by the service. |
Optional |
Set
of string |
fipa-agent-management |
|
languages |
A list of content languages supported by the service. |
Optional |
Set of string |
|
|
ownership |
The owner of the service |
Optional |
string |
|
|
properties |
A list of properties that discriminate the service. |
Optional |
Set of property |
|
1.1.1
Discovery
Middleware Description
This type of object represents the description of
each DM wrapped by the DF.
|
|
|
|
||
|
|
|
|
||
|
|
|
|
|
|
|
|
|
|
|
|
6.1.4
Search Constraints
This type of object represents a set of constraints to limit the function of searching within a directory.
|
Frame Ontology |
search-constraints fipa-agent-management |
|
||
|
Parameter |
Description |
Presence |
Type |
Reserved
Values |
|
max-depth |
The
maximum depth of propagation of the search |
Optional |
integer |
|
|
m |
The maximum number of results to return for the search[20]. A negative value indicates that the sender agent is willing to receive all available results. |
Optional |
integer |
|
|
s |
A globally unique identifier for a search. |
Optional |
string |
|
|
|
|
|
|
|
6.1.5
Agent Management System Agent
Description
Agent Management System Agent
Description
This type of object represents the description of each service registered with the AMS. This is a reification of the Agent Directory Entry from [FIPA00001].
|
Frame Ontology |
ams-agent-description fipa-agent-management |
|
||
|
Parameter |
Description |
Presence |
Type |
Reserved
Values |
|
name |
The identifier of the agent. |
Optional |
agent-identifier[23] |
|
|
ownership |
The owner of the agent. |
Optional |
string |
|
|
state |
The life cycle state of the agent. |
Optional |
string |
initiated active suspended waiting transit |
6.1.6 Agent Platform Description
|
Frame Ontology |
ap-description fipa-agent-management |
|
||
|
Parameter |
Description |
Presence |
Type |
Reserved
Values |
|
Name |
The name of the AP. |
Mandatory |
string |
|
|
Ap-services |
The set of services provided by this AP to the resident
agents. |
Optional |
Set of ap-service |
|
6.1.7
Agent Service Description
|
Frame Ontology |
ap-service fipa-agent-management |
|
||
|
Parameter |
Description |
Presence |
Type |
Reserved Values |
|
Name |
The name of the AP Service. |
Mandatory |
string |
|
|
Type |
The type of the AP Service. |
Mandatory |
string |
fipa.mtp.* |
|
addresses |
A list of the addresses of the service. |
Mandatory |
Sequence of url |
|
6.1.8 Property Template
This is a special object that is useful for specifying parameter/value pairs.
|
Frame Ontology |
property fipa-agent-management |
|
|||
|
Parameter |
Description |
Presence |
Type |
Reserved Values |
|
|
name |
The name of the property. |
Mandatory |
string |
|
|
|
value |
The value of the property |
Mandatory |
term |
|
|
6.2
Function Descriptions
The
following tables define usage and semantics of the functions that are part of
the fipa-agent-management ontology and that are supported by the agent management services and
agents on the AP.
This ontology does not specify any specific positional order to encode the parameters of the objects. Therefore, it is required to encode objects in SL by specifying both the parameter name and the parameter value (see Section 3.6 of [FIPA00008]).
The following terms are used to describe the functions of the fipa-agent-management domain:
· Function. This is the symbol that identifies the function in the ontology.
· Ontology. This is the name of the ontology, whose domain of discourse includes the function described in the table.
· Supported by. This is the type of agent that supports this function.
· Description. This is a natural language description of the semantics of the function.
· Domain. This indicates the domain over which the function is defined. The arguments passed to the function must belong to the set identified by the domain.
· Range. This indicates the range to which the function maps the symbols of the domain. The result of the function is a symbol belonging to the set identified by the range.
· Arity. This indicates the number of arguments that a function takes. If a function can take an arbitrary number of arguments, then its arity is undefined.
6.2.1
Registration
of an Object with an Agent
|
Function |
register |
|
|
Ontology |
fipa-agent-management |
|
|
Supported by |
DF and AMS |
|
|
Description |
The execution of this
function has the effect of registering a new object into the knowledge base
of the executing agent. The DF or AMS description supplied must include a
valid AID. |
|
|
Domain |
df-agent-description / ams-agent-description |
|
|
Range |
The
execution of this function results in a change of the state, but it has no
explicit result. Therefore there is no range set. |
|
|
Arity |
1 |
|
6.2.2
Deregistration of
an Object with an Agent
|
Function |
deregister |
|
|
Ontology |
fipa-agent-management |
|
|
Supported by |
DF and AMS |
|
|
Description |
An agent may
deregister an object in order to remove all of its parameters from a
directory. The DF or AMS description supplied must include a valid AID. |
|
|
Domain |
df-agent-description
/ ams-agent-description |
|
|
Range |
The execution of this function results in
a change of the state, but it has no explicit result. Therefore there is no
range set. |
|
|
Arity |
1 |
|