1. Towards Next Generation Panel at SAINT 2002
Gul Agha
Professor of Computer Science and Computational Science and Engineering
University of Illinois at Urbana-Champaign

2. Research Directions
What are the programming models for Applications on the Internet?
Massively parallel, distributed and mobile.
Multi-agent Systems
Actors
Network Embedded Systems
Integration of continuous and discrete processes.

3. Large Scale Actor Systems
Reasoning about large-scale agent systems.
Asynchrony:
Autonomous agents that communicate asynchronously.
Modularity:
Concurrent components each with several agents.
Locality and Non-interference:
Message are the only means of information flow.
Mobility:
Reconfiguration and extension of systems.

4. Formal Methods
Probabilistic reasoning about distributed and mobile real-time systems:
Techniques for analysis of algorithms.
Performance models.
Models must account for:
Stochastic duration of actions.
Probabilistic behavior of node or system.
Uncertainty in the environment.

5. Metrics for Large-Scale Systems
Probabilities on evolution of system.
Quantifying robustness, stability, timeliness, …
Summations over execution paths for statistical metrics..

6. Models of Time Global synchronous wall clock
Synchronization is too tight
Too detailed an execution model
Asynchronous, distributed time
Vector clocks are too expensive
Application behavior is complicated
Need a more expressive model of time:
Notion of distance and distribution.
Space-Time cone of causal influence.

7. Past causally connected
Causality and Time t
Future causality R P Q
Not Causally related x S
Past causally connected y

8. Agents with Bounded Resources
Each agent has bounded resources.
Dynamic binding of agents to computational and network resources.
Control of Multi-Agent Systems by bounding resources:
Stability
Efficiency
Optimizing search
Preventing denial of service attacks

9. Coordination Algorithms
Large-scale systems where:
Nodes and links have variable capabilities.
Real-time requirements in the absence of a predefined global clock.
Faults are common.

10. Example: Global Snapshot
Consistent with causal relations.
Real-time constraints:
Duration of snapshot “skew”.
Completion time of snapshot.
Scalable
Minimize number of messages.
Dynamic topology of nodes and channels.
Notion of approximation in snapshots:
Farther apart nodes have larger skews.

11. New Directions Hybrid Systems More complex middleware
Network Embedded Systems
More complex middleware
Naming
Computational Reflection
World-Wide Computer
Mobility
Grid-based computing