1. TÆMS-based Execution Architectures

2. Outline Perspective on Coordination (where did TÆMS come from?)
(Local) Scheduling Approaches
Coordination Approaches

3. Perspective on Coordination
Coordination: the act of managing interdependencies between activities
Begs the question of what “managing” and “interdependencies” imply

4. Coordination: “Managing” Interdependencies
Selecting goals/objectives/desires/intentions
Planning to achieve these
Scheduling actions within the resulting plans
Relative action ordering (”choreography”)
Absolute action placement (”synchronization”)
[COORDINATORS has cleverly removed planning from the list]

5. Coordination: Managing “Interdependencies”
If there is a choice, then the particular action/agent chosen matters [SELECTION]
high quality, slow actions vs fast, lower quality approximations
alternative agents
The order in which actions are carried out matters [CHOREOGRAPHY]
hard precedence constraints
soft facilitation opportunities
The time at which actions are carried out matters [SYNCHRONIZATION]
hard or soft deadlines; earliest start times; etc.
time implies ordering across multiple agents

6. Why is Coordination Hard?
No global view
Dynamically changing situation
Uncertainty in the outcomes of actions
Computational complexity of mapping problem (selection + scheduling)
Scale in #agents and #tasks
Deadlines / Time pressure
[NOT in DARPA Coordinators: agent self-interest, non shared utility]

7. TÆMS Task Structure Representation
Representing the “interdependencies” that need to be managed in “complex” domains
worth-oriented (vs. state- or task-oriented)
time-oriented (synchronization, not just choreography)
Objective vs. Subjective reality
Soft (&hard) binary task relationships
Task/goal achievement alternatives w/ characteristic effects
Explicit representation of uncertainty associated with task characteristics & outcomes

8. Cross-cutting Issues Centralized vs. Decentralized solutions
Cooperative Distributed Problem Solving vs. Self-interest
Local Scheduling vs. Coordination

9. Or
Preferred solution depends on the exact utility function (and could change)
And
And
q=10
d=10
q=5
d=5
q=5
d=5
q=1
d=1 S1
q=10, d=15 S2
q=5, d=6

10. Or And And q=10 d=10 q=5 d=5 q=5 d=5 q=1 d=1 S1 ? ? q=10, d=? S2
Non-Local!
q=10
d=10
q=5
d=5
q=5
d=5
q=1
d=1 S1 ? ?
q=10, d=? S2
q=5, d=6

11. Commitments “DO” (task, min quality) “DON’T” (task, max quality)
“Deadline” (task, min quality, max Finish time)
“Earliest Start Time” (task, max quality, min Start time)

12. Scheduling Input Task Structures Non-local Commitments
Scheduler assumes are satisfied
Local Commitments
Commitments ALREADY MADE LOCALLY
Scheduler must attempt to satisfy

13. Scheduling Output SET of valid schedules, and for each one
what commitments are satisfied
what commitments are violated
proposed modification
“value” of schedule w.r.t. utility characteristics
orphaned tasks

14. Decision-Maker Which schedule to execute?
Where do Non-Local Commitments come from?
Manipulation of Scheduler as “what-if” resource
Example: Fake Non-local Commitments
Example: Soft proposal of Local Commitments

15. Outline Perspective on Coordination (Local) Scheduling Approaches
Coordination Approaches

16. RETSINA & DECAF Hard Enablement Only Executing, Enabled, Suspended
FCFS execution of Enabled tasks
DECAF
Slotted one-time schedule of enabled

17. Agent Initialization Dispatcher Planner Scheduler Executor
Plan file
Incoming KQML / FIPA messages
Domain Facts and Beliefs
Outgoing
KQML / FIPA messages
Action Modules
Incoming
Message Queue
Objectives
Queue
Task
Agenda
Task Templates
Hash Table
Pending
Action Queue
Action
Results Queue
Agent
Initialization
Dispatcher
Planner
Scheduler
Executor
[concurrent]

18. DTT & DTC Design-To-Time [Garvey] Blackboard based No initial schedule
Multiple schedule outputs
“negotiation” between Sched & Coord
Design-To-Criteria [Wagner]

19. Simple Temporal Networks
Steve Smith/CMU
heavy use of slack time
fast window propagation

20. DCSPs/DCOPs
ADOPT
DPOP

21. Markov Decision Problem Approaches

22. Other Local Scheduling Approaches

23. Outline Perspective on Coordination (Local) Scheduling Approaches
Coordination Approaches

24. Generalized Partial Global Planning

25. 1) Coordination Points

27. 2) Many Mechanisms

28. Do Do? Do before DL Do before DL? Do after EST Do after EST? A B
enables A B
And of course these are VERY SIMPLE---nothing multi-stage, nothing over 2 agents
AND---OTHER TS Features can use different mechs: Vic Chain Mgr, PGP Redundancy Avoid

29. Mechanism = local rewrite + non-local response
Typically involving an exchange of commitments, analysis of the structure, and local schedule queries on both sides of the exchange

30. 3) Many Schedules
JUST as there where many possible mechanisms, there are many possible schedules
Not

31. Or
Preferred solution depends on the exact utility function (and could change)
And
And
q=10
d=10
q=5
d=5
q=5
d=5
q=1
d=1 S1
q=10, d=15 S2
q=5, d=6

32. Quality depends on Coordination!
Expected quality is not bound just in domain action, but in the outcome of the meta-action of coordination as well!

33. no fixed utility
Not abstract “govt politics” but practical--- Human interface may need to plan different presentation of information (change in interest, change in impact, even change in formatting)

34. 4) Mechanism & Schedule Choice
Requires situation analysis by the coordination component, not just scheduling information
NEGOTIATION between Coordination and Scheduling

35. B B

36. 5) Non-local Commitments
Made by coordination component w.r.t. some mechanism
Include information on the IMPORTANCE and NEGOTIABILITY of CMT.
Help assess NON-LOCAL IMPACT without GLOBAL KNOWLEDGE

38. Commitment includes “easy to reschedule”
Garvey proposed MULTIPLE scheduling solutions, partly evaluated by the Coodination component

39. Coordination
Scheduling

40. Distributed Mgmt of Flexible Times Schedules

41. Partial Centralization

42. The Honeywell Approach