Design Options for Subscription Managers

1
Design Options for Subscription Managers
Agent-Oriented Information Systems Workshop
_at_AAMAS2005 26th ofJuly 2005, Utrecht, The
Netherlands

• Aloys Mbala, Lin Padgham, and Michael Winikoff
• aloys, linpa, winikoff_at_cs.rmit.edu.au
• RMIT University, Melbourne, Australia

2
Summary

• Introduction
• Issues considered
• Analysis
• Subscription Manager Specifications
• Conclusion

3
Introduction

• Discovery of service providers in open systems ?
  middle agents (MA)
• Need in many cases of ongoing updates of
  information as the situation changes
• i.e. monitoring the arrivals of providers in the
  environment
• The question is
• How to ensure that requesters are informed of the
  arrival of new information sources (providers)
  without having them constantly querying the
  environment?
• The response is having a discovery framework with
• Monitoring and subscription functionalities

4
Introduction

• We explore in this paper Design options for
  Subscription Manager Middle Agent for
• Monitoring the arrival of relevant providers in
  the system
• Starting and ending subscriptions
• Checking the validity of the established
  subscriptions
• Which functionalities should reside in the Middle
  Agent and the cost and benefits of alternatives
  approaches
• In order to have a complete solution, one should
  also define
• A description language for the services
• A matching mechanism
• We do not explore these issues here

5
Issues considered

• Looking at interaction between MA and end-agents
  i.e. not the structure of the MA
• Assuming a basic matchmaking capability and
  adding a Subscription Management function
• Middle Agent (MA) ? Subscription Manager (SM)
• We are looking at
• Monitoring the arrivals of providers in the
  systems
• Starting subscriptions
• Ending subscriptions
• Checking the liveness of providers in the system

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Monitoring of new Arrivals

• Incomplete who sets subscriptions? Who ends
  them? Who checks the liveness of agents involved
  in a subscription?

7
Adding a Requester Message traffic Analysis
P
P
R
MA
R
P
P
P
R
P
R
R
R
R
8
Adding a Requester Message traffic Analysis
P2
PF
R
MA
R
P
P
P1
R
P
R
R
R
R
9
Adding a Provider Message traffic Analysis
P
P
P
MA
R
P
P
P
R
P
R
R
R
R
10
Adding a Provider Message traffic Analysis
P
P
P
MA
RF
P
P
P
R1
P
R
R
RS
R2
11
Message Traffic Analysis
12
Monitoring the liveness by the MA
P
R
MA
R
P
P
R
R
R
R
13
Monitoring the liveness by the requesters
RS
P
RS
R2
R1
R2
P
MA
R1
P
RS
P
R1
RS
R2
R2
R1
14
Message Traffic Analysis
15
Subscription Manager Specifications

• Allow the four types of subscription requests
• Single-match
• a list of matching providers is returned to the
  requester
• no further update.
• Subscriptions made by the requester
• Ongoing-match
• a list of matching providers is returned to the
  requester
• Update made when a new matching provider joins
  the system.
• Subscriptions made by the requester
• Subscribe-one
• Subscription made by the MA on behalf of the
  requester
• Subscription to only one provider at once
• Subscribe-all
• Subscription made by the MA on behalf of the
  requester
• Subscription to all matching providers

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Subscription Manager Specification

• The SMs interface should allow
• A requester to cancel its request
• A provider to cancel its registration
• Cancellation of subscriptions done directly by
  the end-agents
• The analysis doesnt show an advantage of having
  the cancellation done by the Subscription Manager
• Liveness Monitoring done by the Subscription
  Manager
• The analysis shows a significant traffic message
  saving when done by the SM rather than
  end-agents.

17
Conclusion

• Subscription Managers are needed in systems
  involving ongoing information provision to
  requesters
• In this paper we considered some aspects of
  long-life subscriptions as
• Discovering providers and subscribing to them
• Ending subscriptions
• Monitoring the liveness of agents in the system
• We provided an analysis that can help in the
  design choices
• We outlined some initial specifications of such
  Subscription Managers