FIPA Request Interaction Protocol Specification


Document title

FIPA Request Interaction Protocol Specification

Document number


Document source

FIPA TC Communication

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Date of this status





Change history        

See Informative Annex A — ChangeLog












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1     FIPA Request Interaction Protocol 1

1.1      Explanation of the Protocol Flow. 1

1.2      Exceptions to Protocol Flow. 2

2     References. 4

3     Informative Annex A — ChangeLog. 5

3.1      2002/11/01 - version G by TC X2S. 5

3.2      2002/12/03 - version H by FIPA Architecture Board. 5

1         FIPA Request Interaction Protocol

The FIPA Request Interaction Protocol (IP) allows one agent to request another to perform some action.


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




Figure 1: FIPA Request Interaction Protocol


1.1        Explanation of the Protocol Flow

The FIPA Request Interaction Protocol (IP) allows one agent to request another to perform some action. The Participant processes the request and makes a decision whether to accept or refuse the request. If a refuse decision is made, then “refused” becomes true and the Participant communicates a refuse. Otherwise, “agreed” becomes true.


If conditions indicate that an explicit agreement is required (that is, “notification necessary” is true), then the Participant communicates an agree. The agree may be optional depending on circumstances, for example, if the requested action is very quick and can happen before a time specified in the reply-by parameter. Once the request has been agreed upon, then the Participant must communicate either:


·         A failure if it fails in its attempt to fill the request,


·         An inform-done if it successfully completes the request and only wishes to indicate that it is done, or,


·         An inform-result if it wishes to indicate both that it is done and notify the initiator of the results.


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 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

[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.


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:             Reworked the protocol flow to make the agree optional which also involved changing the exclusive-or with the agree to a different AUML notation

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 41:                Reworked and expanded the section description of the IP

Page 1, line 50:                Added a new section on Explanation of Protocol Flow

Page 1, line 50:                Reworked and expanded the section on Exceptions of Protocol Flow to incorporate a meta-protocol for cancel

Page 1, line 50:                Added a paragraph explaining the not-understood communication and its relationship with the IP


3.2        2002/12/03 - version H by FIPA Architecture Board

Entire document:              Promoted to Standard status