Intra-role Coordination Using Group Communication: A Preliminary Report

Using Tropos to Model Agent Based Architectures for Adaptive Systems: A Case Study in Ambient Intelligence

“…Nevertheless, it does not fully satisfy yet the specification introduced by [4] for the so called Implicit Organization (IO). An IO is a SOO where there is no predefined (or designtime defined) Providers Organizer role.…”

“…For example, a very simple coordination policy can be established by assuming the winner as the member that first answers to the service request. At this level of design, we do not care about the details concerning the winner election process; anyway, we notice that several negotiating policies can be adopted, like, for example, the Plain Competition policy, the Simple Collaboration policy, the Multicast Contract Net policy, or the Master-Slave policy, as described in [4].…”

“…An IO is a SOO where there is no predefined (or designtime defined) Providers Organizer role. Instead, each of the providers participating at the SOO may, at runtime, assume the role of organizer, as a result of an election process for the selection of the organizer [4] (here called Winner). The term 'implicit' highlights the fact that there is no group formation phase -since joining an organization is just a matter of tuning on a channel, without explicit awareness about the organization or its members.…”

“…Among all the Providers of the Implicit Organization there is a (see the "isa" link) run-time selectedaccordingly with a defined selection policy [4]Winner, which plays the role of coordinator, and which may change from time to time at every IO formation. For example, a very simple coordination policy can be established by assuming the winner as the member that first answers to the service request.…”

“…As mentioned, our patterns require a group communication infrastructure. To this end, we adopt the LoudVoice [4] experimental communication infrastructure based on channeled multicast and developed at our institute. Specifically, LoudVoice uses the fast but inherently unreliable IP multicast -which is not major limitation in our domain, since the communication media in use are unreliable by their own nature.…”