FOUNDATION FOR INTELLIGENT PHYSICAL AGENTS

FIPA Request When Interaction Protocol Specification

Document title	FIPA Request When Interaction Protocol Specification
Document number	XC00028G	Document source	FIPA TC Communication
Document status	Experimental	Date of this status	2002/11/01
Supersedes	None
Contact	fab@fipa.org
Change history	See Informative Annex A — ChangeLog

Notice

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 companies and universities that are active in the field of agents. FIPA makes the results of its activities available to all interested parties and intends to contribute its results to the appropriate formal standards bodies where appropriate.

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Contents

1 FIPA Request When Interaction Protocol 1

1.1 Explanation of the Protocol Flow. 1

1.2 Exceptions to Interaction Protocol Flow. 2

2 References. 3

3 Informative Annex A — ChangeLog. 4

3.1 2002/11/01 - version G by TC X2S. 4

1 FIPA Request When Interaction Protocol

The FIPA Request When Interaction Protocol (IP) allows an agent to request that the receiver perform some action at the time a given precondition becomes true. This IP provides a framework for the request-when communicative act (see [FIPA00037]).

The representation of this IP is given in Figure 1 which is based on extensions to UML1.x. [Odell2001]. This protocol is identified by the token fipa-request-when as the value of the protocol parameter of the ACL message.

Figure 1: FIPA Request When Interaction Protocol

1.1 Explanation of the Protocol Flow

The initiator uses the request-when action to request that the participant do some action once a given precondition becomes true. If the requested agent understands the request and does not initially refuse, it will agree (see [FIPA00037]) and wait until the precondition occurs. Then, it will attempt to perform the action and notify the requester accordingly.

If after the initial agreement the participant is no longer able to perform the action, then it will send a failure action (see [FIPA00037]) to the initiator. Once the action has completed and the failure, inform-done, or inform-result has been sent, the conversation ends.

Any interaction using this interaction protocol is identified by a globally unique, non-null conversation-id parameter, assigned by the Initiator. The agents involved in the interaction must tag all of its ACL messages with this conversation identifier. This enables each agent to manage its communication strategies and activities, for example, it allows an agent to identify individual conversations and to reason across historical records of conversations.

1.2 Exceptions to Interaction Protocol Flow

At any point in the IP, the receiver of a communication can inform the sender that it did not understand what was communicated. This is accomplished by returning a not-understood message. As such, Figure 1 does not depict a not-understood communication as it can occur at any point in the IP. The communication of a not-understood within an interaction protocol may terminate the entire IP and termination of the interaction may imply that any commitments made during the interaction are null and void.

At any point in the IP, the initiator of the IP may cancel the interaction protocol by initiating the meta-protocol shown in Figure 2. The conversation-id parameter of the cancel interaction is identical to the conversation-id parameter of the interaction that the Initiator intends to cancel. The semantics of cancel should roughly be interpreted as meaning that the initiator is no longer interested in continuing the interaction and that it should be terminated in a manner acceptable to both the Initiator and the Participant. The Participant either informs the Initiator that the interaction is done using an inform-done or indicates the failure of the cancellation using a failure.

Figure 2: FIPA Cancel Meta-Protocol

This IP is a pattern for a simple interaction type. Elaboration on this pattern will almost certainly be necessary in order to specify all cases that might occur in an actual agent interaction. Real world issues such as the effects of cancelling actions, asynchrony, abnormal or unexpected IP termination, nested IPs, and the like, are explicitly not addressed here.

2 References

[FIPA00037] FIPA Communicative Act Library Specification. Foundation for Intelligent Physical Agents, 2000. http://www.fipa.org/specs/fipa00037/

[Odell2001] Odell, James, Van Dyke Parunak, H. and Bauer, B., Representing Agent Interaction Protocols in UML. In: Agent-Oriented Software Engineering, Ciancarini, P. and Wooldridge, M., Eds., Springer, pp. 121-140, Berlin, 2001.
http://www.fipa.org/docs/input/f-in-00077/

3 Informative Annex A — ChangeLog

3.1 2002/11/01 - version G by TC X2S

Page 1, Figure 1: The communication labeled inform-ref was changed to inform-result for clarity; the purpose of this communication is to inform the initiator of a result and inform-result implies inform-done

Page 1, Figure 1: The not-understood communication was removed

Page 1, Figure 1: To conform to UML 2, the protocol name was placed in a boundary, x is removed from the diamonds (xor is now the default) and the template box was removed

Page 1, line 42: Reworked and expanded the section description of the IP

Page 1, line 56: Added a new section on Explanation of Protocol Flow

Page 1, line 56: Reworked and expanded the section on Exceptions of Protocol Flow to incorporate a meta-protocol for cancel

Page 1, line 56: Added a paragraph explaining the not-understood communication and its relationship with the IP