FOUNDATION FOR INTELLIGENT
PHYSICAL AGENTS
FIPA Agent Message Transport Protocol
for IIOP Specification
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Document title |
FIPA Agent Message Transport Protocol for IIOP Specification |
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Document number |
XC00075C |
Document source |
FIPA Agent Management |
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Document status |
Experimental |
Date of this status |
2000/07/20 |
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Supersedes |
OC00024 |
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Contact |
fab@fipa.org |
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Change history |
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2000/04/17 |
Separated out from specification OC00024 |
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2000/06/06 |
Made ready for Experimental status |
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2000/06/13 |
FAB editorial and consistency changes; Approved for Experimental |
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2000/07/20 |
Modified the IDL interface with the new Envelope structured type |
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© 2000 Foundation for Intelligent Physical Agents - http://www.fipa.org/
Geneva, Switzerland
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Notice |
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Use of the technologies described in this specification may infringe
patents, copyrights or other intellectual property rights of FIPA Members and
non-members. Nothing in this specification should be construed as granting
permission to use any of the technologies described. Anyone planning to make
use of technology covered by the intellectual property rights of others
should first obtain permission from the holder(s) of the rights. FIPA
strongly encourages anyone implementing
any part of this specification to determine first whether part(s)
sought to be implemented are covered by the intellectual property of others,
and, if so, to obtain appropriate licenses or other permission from the
holder(s) of such intellectual property prior to implementation. This
specification is subject to change without notice. Neither FIPA nor any of
its Members accept any responsibility whatsoever for damages or liability,
direct or consequential, which may result from the use of this specification. |
Foreword
The Foundation for Intelligent Physical
Agents (FIPA) is an international organization that is dedicated to promoting
the industry of intelligent agents by openly developing specifications
supporting interoperability among agents and agent-based applications. This
occurs through open collaboration among its member organizations, which are
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bound to implement or use specific agent-based standards, recommendations and
FIPA specifications by virtue of their participation in FIPA.
The FIPA specifications are
developed through direct involvement of the FIPA membership. The status of a
specification can be either Preliminary, Experimental, Standard, Deprecated or
Obsolete. More detail about the
process of specification may be found in the FIPA Procedures for Technical
Work. A complete overview of the FIPA specifications and their current status
may be found in the FIPA List of Specifications. A list of terms and
abbreviations used in the FIPA specifications may be found in the FIPA
Glossary.
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registered in Geneva, Switzerland. As of January 2000, the 56 members of FIPA
represented 17 countries worldwide.
Further information about FIPA as an organization, membership information, FIPA
specifications and upcoming meetings may be found at http://www.fipa.org/.
Contents
2 Message Transport Protocol for IIOP
2.3 ACC Processing of
IDL Envelope
2.4 Concrete Message
Envelope Syntax
This document is part
of the FIPA specifications and deals with message transportation between
inter-operating agents. This document also forms part of the FIPA Agent
Management Specification [FIPA00023] and contains specifications for:
· The transportation of messages between agents using the Internet Inter-Orb Protocol (IIOP - see [OMGiiop]).
This MTP is based on the transfer of an OMG IDL structure containing the message envelope and an octet sequence representing the ACL message body. The envelope and the message body are transferred together within a single IIOP one-way invocation [OMGiiop].
Once the request has been received, the
message envelope is used by the ACC to obtain the instructions and information
needed to correctly handle the message body.
The name assigned to
this component is:
fipa.mts.mtp.iiop.std
The following IDL specifies the message transport interface. This interface contains a single operation message() that requires a single argument. This argument has two attributes: a sequence of Envelope structures holding the message envelope, and the payload, that is a sequence of octets containing the ACL message body.
module FIPA {
typedef sequence<Envelope> Envelopes;
typedef sequence<octet> Payload;
struct FipaMessage {
Envelopes messageEnvelopes;
Payload
messageBody;
};
interface MTS {
oneway void message(in FipaMessage
aFipaMessage);
};
};
According to [FIPA00067], a FIPA compliant ACC is not allowed to modify any element of the envelope that it receives. It is however allowed to update a value in one of the envelope slots by adding a new Envelope element at the end of the messageEnvelopes sequence. This new element is required to have only those slot values that the ACC wishes to add or update plus a new ReceivedObject element as mandated in [FIPA00067].
As a consequence, an ACC that receives a message must implement the procedure described in the following pseudo-code. The procedure recomposes the full envelope structure with its latest values for each slot. The procedure simply shows that the ACC starts from the last envelope in the sequence and continues until it has all the required values for each slot of the envelope.
EnvelopeWithAllFields := new empty Envelope;
while ( (EnvelopeWithAllFields does not contain
values for all its fields)
OR
(all Envelopes in the sequence have been processed) ) {
// the ACC
gets the next envelope in the sequence starting from the end
tempEnvelope
= getNextEnvelope;
foreach
field in an envelope {
if ((this
field has no value in envelopeWithAllFields)
AND
(this field has a value in tempEnvelope))
then copy
the value of this field from tempEnvelope to envelopeWithAllFields
}
}
EnvelopeWithAllFields now contains the latest values for all its fields.
For example:
Envelope(0):
to = tizio
from =
caio
aclRepresentation = XML
received =
…
Envelope (1):
from =
caio@molfetta.it
received =
…
Envelope (2) :
intended-receiver = tizio@villardora.it
received =
…
EnvelopeWithAllFields:
to =
tizio
(from envelope 0)
from =
caio@molfetta.it (from
envelope 1)
intended-receiver = tizio@villardora.it (from envelope 2)
date = 25
May 2000 (from
envelope 0)
The Abstract Envelope Syntax from [FIPA00067] maps into a set of OMG IDL structured types, all of which are enclosed within the FIPA module.
The following standard convention applies for the identification of optional slots: an empty string and an empty sequence identify the non-presence of a slot.
The complete IDL definition is:
module FIPA {
// No need for an URL struct, since it's
only put in the
// message envelope for informational
purposes.
typedef string URL;
typedef sequence<string> strings; // a
sequence of strings
// this generic type is used to represent
user-defined, non FIPA-defined,
// properties that are added to the message
envelope in the form of a
// keyword and value pair.
struct Property {
string keyword;
any value;
};
struct AgentID { // Agent Identifier
string name;
sequence<AgentID> addresses;
sequence<AgentID> resolvers;
sequence<Property> userDefinedProperties;
};
typedef sequence<AgentID>
AgentIDs; // sequence of Agent
Identifiers
// IDL struct to represent a time stamp.
// It is based on the ISO8601 format with
extension for millisecond durations.
// The value of the typeDesignator must be a
valid
// AlphaCharacter, i.e. ['a'-'z' , 'A'-'Z'],
that identifies the timezone.
// ISO8601 reports the mapping between
typeDesignator and timezone.
// The typeDesignator for UTC is the
character 'Z'.
// If the value of typeDesignator is not an
AlphaCharacter, it defaults
// to the local timezone.
struct DateTime {
short year; // year (e.g. 2000)
short month; // between 1 and 12
short day; // between 1 and 31
short hour; // between 0 and 23
short minutes; // between 0 and 59
short seconds; // between 0 and 59
short milliseconds; // between 0 and 999
char
typeDesignator; // see comment above
};
struct ReceivedObject {
URL by;
URL from;
DateTime date;
string id;
string via;
};
typedef
sequence<Property> TransportBehaviourType;
struct Envelope {
AgentIDs to;
AgentID from;
string comments;
string aclRepresentation;
long payloadLength;
string payloadEncoding;
DateTime date;
strings encrypted;
AgentIDs intendedReceiver;
ReceivedObject received;
TransportBehaviourType transportBehaviour;
sequence<Property> userDefinedProperties; // user-defined
properties
};
typedef sequence<Envelope> Envelopes;
typedef sequence<octet> Payload;
struct FipaMessage {
Envelopes messageEnvelopes;
Payload
messageBody;
};
interface MTS {
oneway void message(in FipaMessage
aFipaMessage);
};
};
[FIPA00023] FIPA Agent
Management Specification. Foundation for Intelligent
Physical Agents, 2000. http://www.fipa.org/specs/fipa00023/
[FIPA00067] FIPA Agent Message Transport Service Specification. Foundation for Intelligent Physical Agents, 2000. http://www.fipa.org/specs/fipa00067/
[OMGiiop] OMG Internet Inter-ORB Protocol Specification, Common Object Request Broker Architecture 2.2. Object Management Group, 1999.