Kenneth P. Birman

N. Rama Rao Professor of Computer Science

4119 Upson Hall, Cornell University

Ithaca, New York 14853

Work: 607-255-9199

Mobile: 607-227-0894

Email: ken@cs.cornell.edu

Recent News: The Isis2 System is available for download!

· Isis² is our new platform for building scalable, strongly consistent, cloud computing services. Developed by me over a two year period, the system is going to be our main focus for the next few years, and we intend to make it work, well, even in massive scenarios. Of course, nothing ever works outside the cases in which we've tested, and up to now our testing has focused on replication in services with up to about 1000 member processes, with consistency that can range from a weak form of durability ideal for first-tier "soft state" cloud services to a much stronger form that matches what Paxos offers, but scales far beyond what normal Paxos systems can do (we know because the system also includes a full Paxos implementation and we’ve compared the two side-by-side). Configurations with far more than 1000 nodes are planned for 2012. In addition to the basics (group communication, virtual synchrony model, etc) we also have a key-value option that shards data within a big group, using a user-determined replication factor (think of Amazon's Dynamo shopping cart), security features, automated logging and checkpoint-recovery, and a wide range of other features.

· To learn more, visit the Isis² web page.

· To learn even more, wait for the new edition of Ken's Reliable Distributed Systems textbook. In a totally biased manner, the new edition of my textbook will expand coverage of cloud computing, using Isis² as its "model" for how to solve high-assurance cloud problems. Of course this isn't as unfair as it may sound, since the major cloud platforms mostly lack anything like Isis². The book should be out early in 2012, from Springer Verlag. I’m teaching Cornell’s CS5412 Cloud Computing class this spring; my materials are online and you are welcome to use them.

Current Research (full publications list):

• Cloud computing, Isis², and immersive virtual reality applications. My research is concerned with what people have started to call "Cloud Computing" and "Edge Computing". Here's are links (videos but you need to click "expert perspectives", or text) to a non-technical interview on this topic. Of course, Cloud Computing is just the buzzword of the day. Back before these terms gained wide use, we would have said that I work on reliable distributed computing, applications involving reliable information collection or dissemination, and problems associated with security in complex distributed systems.
  
  My main recent focus has been on massive scalability -- building really big computing systems that remain stable even under stress, overload, or when components fail or are restarted. We have DARPA funding for this project under the new Mission-Oriented Resilient Cloud program, and are very excited about the potential. This activity is our main one at the present time.

• Theory of consistent replication. Curious to know what a virtually synchronous version of Paxos would look like? Check out the recent paper Dahlia and Robbert and I wrote, combining the virtual synchrony and state machine replication (Paxos) models. In some sense this closes a chapter. If you find the history of such things interesting, you might enjoy the paper I wrote for a recent Springer Verlag LNCS volume on replication in distributed systems. The unified model isn't just theory: I'm using it in the Isis² system, and Robbert has a suite of protocols, implemented very concisely in Erlang, that match the paper really closely and are suitable for formal analysis using theorem proving tools.
  
  In fact we have a pretty active theoretical side to our group. Robbert and I do a lot of work with Bob Constable's NuPRL group on formal methods, which seem very powerful in this area. I also collaborate with Ymir Vigfusson, currently at IBM Haifa finishing a post-doc, Idit Keidar, and others... a very active area for researchers, worldwide.
  
  
• Technology for the Smart Electric Power Grid. Under a new grant from the Department of Energy GENI program we’re applying our insights concerning high assurance cloud computing and Isis² to the challenge of controlling the smart power grid. This style of embedded cloud-hosted real-time system could have many other applications.

• Future Internet Architectures. Robbert and I also have an increasingly active effort in the area of routers for the modern "cloud-enabled" Internet. The basic argument here is that as we move towards putting all sorts of very sensitive, mission-critical things on the cloud, we need ways to build those applications (hence Isis²) but we also need ways to harden the Internet itself - the routers that support those fancy cloud applications. We're working closely with Cisco on this topic, and have a few papers now, and are part of the NEBULA team in the NSF-funded Future Internet Architectures program. I'm really excited about the area, although (between you and me) my approach is going to start by using Isis² right on the routers themselves, to build highly available versions of things like BGP. But check out these two papers, one on measurements of network quality of service over long distances, and one on making TCP connections unbreakable. They should give you a sense of why the area seems so exciting to my group.

Older work. I've really worked in Cloud Computing for most of my career, although it obviously wasn't called cloud computing in the early days. As a result, our papers in this area date back to 1985. Some examples of mission-critical systems on which my software was used in the past include the New York Stock Exchange and Swiss Exchange, the French Air Traffic Control system, the AEGIS warship and a wide range of applications in settings like factory process control and telephony. In fact, every stock quote or trade on the NYSE from 1995 until early 2006 was reported to the overhead trading consoles through software I personally implemented - a cool (but also scary) image, for me at least! During the ten years this system was running, many computers crashed during the trading day, and many network problems have occurred - but the design we developed and implemented has managed to reconfigure itself automatically and kept the overall system up, without exception. They didn't have a single trading disruption during the entire period. As far as I know, the other organizations listed above have similar stories to report.

Today, these kinds of ideas are gaining "mainstream" status. For example, IBM's Websphere 6.0 product includes a multicast layer used to replicate data and other runtime state for high-availability web service applications and web sites. Although IBM developed its own implementation of this technology, we've been told by the developers that the architecture was based on Cornell's Horus and Ensemble systems, described more fully below. The CORBA architecture includes a fault-tolerance mechanism based on some of the same ideas. And we've also worked with Microsoft on the technology at the core of the next generation of that company's clustering product. So, you'll find Cornell's research not just on these web pages, but also on web sites worldwide and in some of the world's most ambitious data centers and high availability computing systems.

In fact we still have very active dialogs with many of these companies: Cisco, IBM, Intel, Microsoft, Red Hat, and others. An example of an ongoing dialog is this: we’ve been working with Cisco to invent a new continuous availability option for their core Internet routers, the CRS-1 series. You can read about this work here.

A major emerging opportunity involves management of new kinds of networks. The issue here is that applications such as secure conferencing systems need to administer resources at multiple locations and to do so in a secure, reliable way, perhaps while handling enormous data rates and rapid changes in configuration. Some types of networks involve placing agents (for example, content filtering or overlay routing components) at large numbers of routers. Thus, scalable replication, security policy and key management, system monitoring and control are rapidly becoming critical requirements. Our work is directly applicable in such settings.

My group often works with vendors and industry researchers. We maintain a very active dialog with the US government and military on research challenges emerging from a future generation communication systems now being planned by organizations like the Air Force and the Navy. We've even worked on new ways of controlling the electric power grid, but not in time to head off the big blackout in 2003! Looking to the future, we are focused on needs arising in financial systems, large-scale military systems, and even health-care networks. (In this connection, I should perhaps mention that although we do get research support from the government and the US military, none of our research is classified or even sensitive, and all of it focuses on widely used commercial standards and platforms. Most of our software is released for free, under open source licenses.)

I'm just one of several members of a group in this area at Cornell. My closest colleagues and co-leaders of the group are Robbert van Renesse and Hakim Weatherspoon. We also collaborate with Gun Sirer, Paul Francis, Al Demers and Johannes Gehrke, as well as with other systems faculty members at Cornell: Andrew, Fred, Rafael, Joe, etc. The systems group is close-knit, and many of our students are jointly advised by other faculty members in the systems area. Werner Vogels worked with us until September 2004, when he joined Amazon.com as Vice President and Director for Systems Research.

Four generations of reliable distributed systems research! Overall, our group has developed three generations of technology and is now working on a fourth generation system: The Isis Toolkit, developed mostly during 1987-1993, the Horus system, developed starting in 1990 until around 1995, the Ensemble system, 1995-1999. Right now we're developing a number of new systems including Isis², Gradient, and the reliable TCP solution mentioned above, and working with others to integrate those solutions into settings where reliability, security, consistency and scalability are make-or-break requirements.

Older Research web pages:

Live Objects, Quicksilver, Maelstrom, Ricochet and Tempest projects
Ensemble project
Horus project
Isis project (really old stuff!)

A collection of papers on Isis, edited by myself with Robbert van Renesse, may still be available -- it was called Reliable Distributed Computing with the Isis Toolkit and was in the IEEE Press Computer Science series.

Teaching: During Spring 2012 I'll be running an MEng-oriented course on cloud computing: CS5412. Please consult the course web page for more information. We are hoping to make videonotes from the classes available on the course web site, and all of my slide sets are available for public download and use.

Graduate Studies in Computer Science at Cornell: At this time of the year, we get large numbers of inquiries about our PhD program. I want to recommend that people interested in the program not contact faculty members like me directly with routine questions like "can your research group fund me". As you'll see from the web page, Cornell does admissions by means of a committee, so individual faculty members don't normally play a role. This is different from many other schools -- I realize that at many places, each faculty member admits people into her/his own group. But at Cornell, we admit you first, then you come here, and then you affiliate with a research group after a while. Funding is absolutely guaranteed for people in the MS/PhD program during the whole time they are at Cornell. On the other hand, students in the MEng program generally need to pay their own way.

Obviously, some people have more direct, specific questions, and there is no problem sending those to me or to anyone else. But as for the generic "can I join your research group?" the answer is that while I welcome people into the group if they demonstrate good ideas and talent in my area, until you are here and take my graduate course and spend time talking with me and my colleagues, how can we know if the match is good? And most such inquiries are from people who haven't yet figured out quite how many good projects are underway at Cornell. Perhaps, on arrival, you'll take Andrew Myer's course in language based security and will realize this is your passion. So at Cornell, we urge you to take time to find out what areas we cover and who is here, to take some courses, and only then affiliate with a research group. But please knock on my door any time you like! I'm more than happy to talk to any student in the department about anything we're doing here!