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Harry C. Li - Ph.D. Student
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| research |
paper
pdfs |
python
& systems |
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LasrWiki Dr. Hamming's Research Advice |
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Python PyCrypto PyOpenSSL Twisted |
| About my research |
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| I am broadly interested in overlay networks, p2p systems, (Byzantine) fault-tolerance, game theory, mechanism design, and mesh routing protocols. | ||
| Current |
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| I'm currently
interested in designing and implementing cooperative services. These
services take many forms; e.g., p2p applications, content distribution
networks, and mesh routing protocols. These approaches are very
attractive because they can be highly fault-tolerant, scalable, and
adaptive. BitTorrent, KaZaA, Limewire, Skype, and LiveStation are a
small sample of today's well-known cooperative applications. All of
these services rely on a shared principle: cooperation. Users work
together to achieve a common goal, pooling their resources to
accomplish tasks that would be difficult perhaps infeasible to tackle
alone. Cooperation is at the heart of these services, which leads to an
obvious question: What if users stop cooperating? In these services, some nodes may fail arbitrarily while the remaining may behave selfishly. My work blends game theory with traditional distributed systems to build robust cooperative services that can tolerate failures while incentivizing users to work together. The main challenge is in designing these systems to perform well while providing sufficient incentives and punishments to induce cooperation. Creating a system that performs well when all participants cooperate is not enough. Neither is designing a mechanism that induces cooperation but performs poorly. My research explores how to balance these two desires to build systems that are far more robust than anything currently available. |
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| Less Current |
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| Prior to working in
peer-to-peer systems, I was looking into Paxos protocols. My research
there stemmed from two observations. First, very few people actually
understood how Castro and Liskov's PBFT protocol worked. Second,
despite calling PBFT by the name Byzantine Paxos, no one really
understood in what ways PBFT was similar and different from the
original Paxos. Further, despite many claims that various protocols
were a Byzantine-version or disk-variant of Lamport's seminal Paxos
algorithm, no one could say why a protocol was 'Paxos-like'. What were
the similarities? And why were those similarities enough to make
something a Paxos derivative? These observations led to the creation of the Paxos Register, a new and intuitive abstraction that captures the similarities across Paxos variants. We showed our abstraction could capture three very different Paxos-like protocols. Our deepening understanding of Paxos also led to the creation of an information-theoretically secure Byzantine Paxos that uses secret sharing instead of cryptography. We believe this insight shows not just the flexibility of the Paxos Register, but also its power. |
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| Undergraduate days |
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| As an undergraduate at Brown University, I worked with Shriram Krishnamurthi and Kathi Fisler on identifying some problems in modular feature verification and proposing some initial solutions based upon three-valued model checking. | ||
Publications: |
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| Harry C. Li, Allen Clement, Mirco Marchetti, Manos Kapritsos, Luke Robison, Lorenzo Alvisi, and Mike Dahlin. FlightPath: Obedience vs. Choice in Cooperative Services. In Proceedings of the 8th Operating Systems Design and Implementation (OSDI 2008), San Diego, California, December 2008. pdf pre-alpha tarball | ||
| Federico Mari, Igor Melatti,
Ivano Salvo, Enrico Tronci, Lorenzo Alvisi, Allen Clement and Harry C.
Li. Model Checking Nash Equilibria in
MAD Distributed Systems. In Proceedings
of the 8th Symposium on Formal Methods in Computer Aided Design (FMCAD'08), Portland, Oregon,
November 2008. |
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| Allen Clement, Harry C. Li, Jeff Napper, J.P. Martin, Lorenzo Alvisi, and Mike Dahlin. BAR Primer. In Proceedings of the International Conference on Dependable Systems and Networks (DSN 2008), DCC Symposium, Anchorage, Alaska, June 2008. pdf | ||
| Harry C. Li, Allen Clement, Amitanand Aiyer, and Lorenzo Alvisi. The Paxos Register. In Proceedings of the 26th IEEE International Symposium Reliable Distributed Systems (SRDS '07), Beijing, China, October 2007. pdf | ||
| Lorenzo
Alvisi, Jeroen Doumen,
Rachid Guerraoui, Boris Koldehofe, Harry C. Li, Robbert van Renesse,
and Gilles Tredan. How
Robust Are Gossip-Based Communication Protocols? In SIGOPS
Operating Systems Review 41,
5 (Oct. 2007), 14-18. pdf |
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| Étienne
Riviere, Roberto
Baldoni, Harry C. Li, and José Pereira. Compositional
Gossip: A
Conceptual Architecture for Designing Gossip-Based Applications. In
SIGOPS
Operating Systems Review
41,5 (Oct. 2007), 43-50. pdf |
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| Harry C. Li, Allen Clement, Edmund Wong, Jeff Napper, Indrajit Roy, Lorenzo Alvisi, and Mike Dahlin. BAR Gossip. In Proceedings of the 7th Symposium on Operating System Design and Implementation (OSDI '06), Seattle, WA, November 2006. pdf | ||
| Harry C. Li, Shriram
Krishnamurthi and
Kathi Fisler. Interfaces
for modular feature verification. In ASE
'02:
Proceedings of the 17th IEEE
International Conference on Automated Software Engineering
(ASE'02), Washington, DC, USA, 2002. IEEE Computer Society. pdf |
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| Harry C. Li, Shriram Krishnamurthi and
Kathi
Fisler. Verifying
cross-cutting features as open systems. SIGSOFT
Software Engineering Notes, 27(6):89--98, 2002. pdf |
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| Harry C. Li, Shriram
Krishnamurthi and
Kathi
Fisler. The Influence of Software Modules on
Modular Verification. In
Proceedings of the 9th International SPIN Workshop on Model Checking of
Software (SPIN'02),
60--78, 2002. pdf |
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Technical Reports: |
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| Harry C. Li, Amitanand S. Aiyer, Lorenzo Alvisi, and Allen Clement. Information-Theoretically Secure Byzantine Paxos. The University of Texas at Austin, Department of Computer Sciences. Technical Report TR-07-21. May 18, 2007. pdf | ||
| Harry C. Li, Lorenzo Alvisi and Allen Clement. The Game of Paxos. The University of Texas at Austin, Department of Computer Sciences. Technical Report TR-05-24. May 16, 2005. pdf | ||
| Awards: |
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| James C.
Browne Fellowship awarded by UT Austin (2008) |
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| MCD Fellowship awarded by UT Austin (2002) | ||
| NSF Graduate Fellowship Honorable Mention (2002) | ||
| CRA Outstanding Undergraduate Award Honorable Mention (2001) | ||
