Arun Iyengar

Software Engineer / Computer Scientist / Consultant

☝️To Technical Work Menu

Technical Work

Caching and Dynamic Content Generation for the Web

One of my key technical contributions has been inventing and implementing new techniques for consistently caching dynamic data to improve Web performance. Dynamic Web content can consume orders of magnitude more CPU time to serve than static content. Generating dynamic content is often the performance bottleneck for Web sites, even if only a fraction of the content is generated dynamically. The difficult challenge is to serve dynamic content efficiently while providing current and consistent information.

The following USITS '97 paper describes techniques we developed for caching dynamic data to improve performance at highly accessed real Web sites: "Improving Web Server Performance by Caching Dynamic Data" (with Jim Challenger). In Proceedings of the USENIX 1997 Symposium on Internet Technologies and Systems (USITS '97), Monterey, CA, December 1997.

A key component of this work is a cache which can efficiently store data from Web and other distributed applications via an API invoked by applications, a new concept at the time. The following technical report provides more details of our cache and its API. Since that time, caches of this type (such as memcached, Redis, PHP caches, Python caches, ASP.NET caches, IBM WebSphere DynaCache and eXtreme Scale) have become widely used for improving performance at Web sites as well as in other distributed applications.
"Distributed Cache Manager and API" (with Jim Challenger). IBM Research Report RC 21004(94070), October 1997.

The following papers introduce cache dependencies for maintaining consistency between cached dynamic objects and underlying data which affect their values; the INFOCOM '99 paper describes how they were successfully deployed at a major Web site to significantly improve performance and consistency levels for dynamic data. Since that time, cache dependencies have become commonly used by many developers and are a key feature of tools for building Web sites such as Microsoft's ASP.NET, PHP frameworks such as Yii, and Python.
"Data Update Propagation: A Method for Determining How Changes to Underlying Data Affect Cached Objects on the Web"(with Jim Challenger). IBM Research Report RC 21093(94368), February 1998. "A Scalable System for Consistently Caching Dynamic Web Data" (with Jim Challenger and Paul Dantzig). In Proceedings of IEEE INFOCOM'99, New York, New York, March 1999.

The following paper describes our pioneering use of fragment-based techniques for generating dynamic Web content for highly accessed real Web sites. These techniques allow fragment caching. Since that time, fragment-based Web publication has become widely used and is a key feature of commonly used Web content management systems such as WordPress. Support for fragment caching after our work became extensive. Several PHP frameworks, Microsoft's ASP.NET, Python, and Ruby on Rails support fragment caching as do Oracle, Akamai, and others. "A Publishing System for Efficiently Creating Dynamic Web Data" (with Jim Challenger, Karen Witting, Cameron Ferstat, and Paul Reed). In Proceedings of IEEE INFOCOM 2000, Tel Aviv, Israel, March 2000.

The following papers describe techniques which we have developed for efficiently publishing dynamic content. Several of these techniques can be applied to changing content in many different forms and are not restricted to the Web. The ACM Transactions on Internet Technology and SC papers describe some of our experiences when we deployed our techniques at real highly accessed Web sites. "Automatic Fragment Detection in Dynamic Web Pages and its Impact on Caching" (with Lakshmish Ramaswamy, Ling Liu, and Fred Douglis). Pat Goldberg Memorial Best Paper Award. In IEEE Transactions on Knowledge and Data Engineering vol. 17 #6, June 2005. "A Fragment-Based Approach for Efficiently Creating Dynamic Web Content" (with Jim Challenger, Paul Dantzig, and Karen Witting). In ACM Transactions on Internet Technology vol. 5 #2, May 2005. "Automatic Detection of Fragments in Dynamically Generated Web Pages" (with Lakshmish Ramaswamy, Ling Liu, and Fred Douglis). Best Paper Award. In Proceedings of the 13th International World Wide Web Conference (WWW2004), New York City, May 2004. "Application-Specific Delta-Encoding via Resemblance Detection" (with Fred Douglis). In Proceedings of the 2003 USENIX Annual Technical Conference (USENIX '03), San Antonio, Texas, June 2003. "A Scalable and Highly Available System for Serving Dynamic Data at Frequently Accessed Web Sites" (with Jim Challenger and Paul Dantzig). In Proceedings of ACM/IEEE Supercomputing '98 (SC98), Orlando, Florida, November 1998.

The ability to cache dynamic content can greatly improve performance. Many systems do not allow dynamic content to be cached because of the problem of maintaining consistency. The following papers describe techniques we have developed for consistently caching dynamic data. The IEEE/ACM Transactions on Networking paper describes our experiences caching dynamic data for real highly accessed Web sites. "Efficiently Serving Dynamic Data at Highly Accessed Web Sites" (with Jim Challenger, Paul Dantzig, Mark Squillante, and Li Zhang). In IEEE/ACM Transactions on Networking vol. 12 #2, April 2004. "Engineering Web Cache Consistency" (with Jian Yin, Lorenzo Alvisi, and Mike Dahlin). In ACM Transactions on Internet Technology vol. 2 # 3, August 2002. "Engineering server-driven consistency for large scale dynamic web services" (with Jian Yin, Lorenzo Alvisi, and Mike Dahlin). Best Paper Award. In Proceedings of the 10th International World Wide Web Conference (WWW10), Hong Kong, May 2001.

Caching is extremely important for improving the performance of distributed systems and can be deployed at multiple places. The following papers describe work that we have done developing caches applicable to a broad range of distributed applications and not necessarily limited to the Web. The caching systems described in several of these papers have been successful in real deployments. "CHA: A Caching Framework for Home-based Voice Assistant Systems" (with Lanyu Xu and Weisong Shi). In Proceedings of the Fifth ACM/IEEE Symposium on Edge Computing (SEC 2020), November 2020. "Enhanced Clients for Data Stores and Cloud Services". In IEEE Transactions on Knowledge and Data Engineering vol. 31 no. 10, October 2019. "Providing Enhanced Functionality for Data Store Clients". In Proceedings of the 33rd IEEE International Conference on Data Engineering (ICDE 2017), San Diego, California, April 2017. "Cooperative Caching for Efficient Data Access in Disruption Tolerant Networks" (with Wei Gao, Guohong Cao, and Mudhakar Srivatsa). In IEEE Transctions on Mobile Computing vol. 13 no. 3, March 2014. "Byte Caching in Wireless Networks" (with Franck Le and Mudhakar Srivatsa). In Proceedings of the 32nd IEEE International Conference on Distributed Computing Systems (ICDCS 2012), Macau, June 2012. "Distributed Maintenance of Cache Freshness in Opportunistic Mobile Networks" (with Wei Gao, Guohong Cao, and Mudhakar Srivatsa). In Proceedings of the 32nd IEEE International Conference on Distributed Computing Systems (ICDCS 2012), Macau, June 2012. "Supporting Cooperative Caching in Disruption Tolerant Networks" (with Wei Gao, Guohong Cao, and Mudhakar Srivatsa). In Proceedings of the 31st IEEE International Conference on Distributed Computing Systems (ICDCS 2011), Minneapolis, Minnesota, June 2011. "Network-Aware Partial Caching for Internet Streaming Media Delivery" (with Shudong Jin and Azer Bestavros). In ACM/Springer Multimedia Systems Journal vol. 9 #4, October 2003, copyright Springer-Verlag. "Architecture of a Web Server Accelerator" (with Junehwa Song, Eric Levy-Abegnoli, and Daniel Dias). In Computer Networks, vol. 38 #1, January 2002. "Web Proxy Acceleration" (with Daniela Rosu and Daniel Dias). In Cluster Computing, Vol. 4 #4, October 2001. "A Middleware System Which Intelligently Caches Query Results" (with Louis Degenaro, Ilya Lipkind, and Isabelle Rouvellou). In Proceedings of ACM/IFIP Middleware 2000, Palisades, New York, April 2000. "Design and Performance of a General-Purpose Software Cache". In Proceedings of the 18th IEEE International Performance, Computing, and Communications Conference (IPCCC'99), Phoenix/Scottsdale, Arizona, February 1999.

Load Balancing and Scheduling

I co-invented Web load balancing with affinity between specific clients and servers (sticky load balancing).

This work was incorporated into IBM's Network Dispatcher load balancer. Since that time, load balancing with affinity has become widely used and is now a standard feature of just about all commonly used Web load balancers (such as the Apache HTTP Server load balancer and Nginx). Among other things, this is important for supporting high TLS (SSL) request rates for secure (encrypted) communications over the Web such as when credit card transactions are made. Load balancing with affinity is also important for other protocols such as the Session Initiation Protocol (SIP) as described in our INFOCOM 2009 and 2012 IEEE/ACM Transctions on Networking papers.

The techniques described in several of these papers have been successful in real deployments. "Design, Implementation, and Performance of a Load Balancer for SIP Server Clusters" (with Hongbo Jiang, Erich Nahum, Wolfgang Segmuller, Asser Tantawi, and Charles P. Wright). In IEEE/ACM Transctions on Networking, vol. 20 no. 4, August 2012. "Improving Application Placement for Cluster-based Web Applications" (with Chen Tian, Hongbo Jiang, Xue Liu, Zuodong Wu, Jinhua Chen, Wenyu Liu, and Chonggang Wang). In IEEE Transactions on Network and Service Management vol. 8 no. 2, June 2011. "Load Balancing for SIP Server Clusters" (with Hongbo Jiang, Erich Nahum, Wolfgang Segmuller, Asser Tantawi, and Charles P. Wright). In Proceedings of IEEE INFOCOM 2009, Rio de Janeiro, Brazil, April 2009. "How to determine a good multi-programming level for external scheduling" (with Bianca Schroeder, Mor Harchol-Balter, Erich Nahum, and Adam Wierman). In Proceedings of the 22nd IEEE International Conference on Data Engineering, Atlanta, Georgia, April 2006. "A Tiered System for Serving Differentiated Content" (with Huamin Chen). In World Wide Web: Internet and Web Information Systems vol. 6 #4, December 2003. "Architecture of a Web Server Accelerator" (with Junehwa Song, Eric Levy-Abegnoli, and Daniel Dias). In Computer Networks, vol. 38 #1, January 2002. "A Scalable and Highly Available System for Serving Dynamic Data at Frequently Accessed Web Sites" (with Jim Challenger and Paul Dantzig). In Proceedings of ACM/IEEE Supercomputing '98 (SC98), Orlando, Florida, November 1998.

Cloud Computing and Virtualization

"Assigning costs based on computer memory usage". US Patent 10,528,460, issued January 7, 2020, priority date September 22, 2010. This patent discloses new methods for dynamically allocating memory efficiently. A key aspect is charging users based on amounts of memory consumed in cloud and other multi-user environments. This patent is widely used in serverless computing. "Enhanced Clients for Data Stores and Cloud Services". In IEEE Transactions on Knowledge and Data Engineering vol. 31 no. 10, October 2019. "A Trusted Healthcare Data Analytics Cloud Platform," (with Ashish Kundu, Upendra Sharma, and Ping Zhang). In Proceedings of the 38th IEEE International Conference on Distributed Computing Systems (ICDCS 2018), Vienna, Austria, July 2018. KeyValueServe: Design and Performance Analysis of a Multi-tenant Data Grid as a Cloud Service" (with Anwesha Das and Frank Mueller). In Concurrency and Computation: Practice and Experience vol. 30 no. 14, July 2018. MemFlex: A Shared Memory Swapper for High Performance VM Execution" (with Qi Zhang, Ling Liu, and Gong Su). In IEEE Transactions on Computers vol. 66 no. 9, September 2017. "Supporting Data Analytics Applications Which Utilize Cognitive Services". In Proceedings of the 37th IEEE International Conference on Distributed Computing Systems (ICDCS 2017), Atlanta, Georgia, June 2017. "Providing Enhanced Functionality for Data Store Clients". In Proceedings of the 33rd IEEE International Conference on Data Engineering (ICDE 2017), San Diego, California, April 2017. "iBalloon: Efficient VM Memory Balancing as a Service" (with Qi Zhang, Ling Liu, Jiangchun Ren, and Gong Su). Top 5 Picks Award. In Proceedings of the 23rd IEEE International Conference on Web Services (ICWS 2016), San Francisco, CA, June/July 2016. "VM-μCheckpoint: Design, Modeling, and Assessment of Lightweight In-Memory VM Checkpointing" (with Long Wang, Zbigniew Kalbarczyk, and Ravishankar Iyer). In IEEE Transactions on Dependable and Secure Computing vol. 12 no. 2, March/April 2015. "CloudLEGO: scalable cross-VM-type application performance prediction" (with Shicong Meng and others). In Proceedings of the 4th Annual Symposium on Cloud Computing (SoCC '13), Santa Clara, CA, October 2013. "Volley: Violation Likelihood Based State Monitoring for Datacenters" (with Shicong Meng, Isabelle Rouvellou, and Ling Liu). In Proceedings of the 33rd IEEE International Conference on Distributed Computing Systems (ICDCS 2013), Philadelphia, PA, July 2013. "Reliable State Monitoring in Cloud Data Centers" (with Shicong Meng, Isabelle Rouvellou, Ling Liu, Kisung Lee, Balaji Palanisamy, and Yuzhe Tang). Best Paper Award. In Proceedings of the 5th IEEE International Conference on Cloud Computing (CLOUD 2012), Honolulu, Hawaii, June 2012.

Artificial Intelligence and Data Analysis

"Lachesis: Automatic Partitioning for UDF-Centric Analytics" (with Jia Zou et al). To appear in Proceedings of the 47th International Conference on Very Large Data Bases (VLDB 2021), August 2021. “Patient-Specific Seizure Prediction Using Single Seizure Electroencephalography Recording” (with Zaid Bin Tariq, Lara Marcuse, Hui Su, and Bülent Yener). Best Student Paper Award. In Proceedings of the 5th International Workshop on Health Intelligence, (W3PHIAI-21), February 2021. “An Empirical Study of Travel Behavior Using Private Car Trajectory Data” (with Hongbo Jiang, Yu Zhang, Zhu Xiao, and Ping Zhao). In IEEE Transactions on Network Science and Engineering, Volume 8, Issue 1, pp. 53-64, Jan-March 2021. “Real-Time Data Quality Analysis” (with Dhaval Patel, Shrey Shrivastava, Nianjun Zhou, and Anuradha Bhamidipaty). In Proceedings of the 2020 IEEE International Conference on Cognitive Machine Intelligence (CogMI 2020), December 2020. “A Verifiable Imputation Analysis for Univariate Time Series and Enabling Package” (with Nianjun Zhou, Dhaval Patel, Shrey Shrivastava, and Anuradha Bhamidipaty). In Proceedings of the 2020 IEEE International Conference on Big Data (BigData 2020), December 2020. “DQLearn : A Toolkit for Structured Data Quality Learning” (with Shrey Shrivastava, Dhaval Patel, Nianjun Zhou, and Anuradha Bhamidipaty). In Proceedings of the 2020 IEEE International Conference on Big Data (BigData 2020), December 2020. “FLOps: On Learning Important Time Series Features for Real-Valued Prediction” (with Dhaval Patel, Syed Yousaf Shah, Nianjun Zhou, Shrey Shrivastava, Anuradha Bhamidipaty, and Jayant Kalagnanam). In Proceedings of the 2020 IEEE International Conference on Big Data (BigData 2020), December 2020. "CHA: A Caching Framework for Home-based Voice Assistant Systems" (with Lanyu Xu and Weisong Shi). In Proceedings of the Fifth ACM/IEEE Symposium on Edge Computing (SEC 2020), November 2020. “TrajData: On Vehicle Trajectory Collection with Commodity Plug-and-Play OBU Devices” (with Zhu Xiao et al.). In IEEE Internet of Things Journal 7 (9), 9066-9079, September 2020 "Demystifying Learning Rate Polices for High Accuracy Training of Deep Neural Networks" (with Yanzhao Wu et al.). In Proceedings of the 2019 IEEE International Conference on Big Data (BigData 2019), Los Angeles, CA, December 2019. "GRAHIES: Multi-Scale Graph Representation Learning with Latent Hierarchical Structure" (with Lei Yu et al.). In Proceedings of the First IEEE International Conference on Cognitive Machine Intelligence (IEEE CogMI 2019), Los Angeles, CA, 2019. "Providing Cooperative Data Analytics for Real Applications Using Machine Learning" (with Jayant Kalagnanam, Dhaval Patel, Chandra Reddy, and Shrey Shrivastava). In Proceedings of the 39th IEEE International Conference on Distributed Computing Systems (ICDCS 2019), Dallas, Texas, July 2019. "Interpretable Drug Target Prediction Using Deep Neural Representation" (with Kyle Yingkai Gao, Achille Fokoue, Heng Luo, Sanjoy Dey, and Ping Zhang). In Proceedings of the 27th International Joint Conference on Artificial Intelligence ( IJCAI 2018), Stockholm, Sweden, July 2018. "A Knowledge and Reasoning Toolkit for Cognitive Applications" (multiple co-authors). In Proceedings of the Fifth ACM/IEEE Workshop on Hot Topics in Web Systems and Technologies (HotWeb 2017) , San Jose, CA, October 2017. "Supporting Data Analytics Applications Which Utilize Cognitive Services". In Proceedings of the 37th IEEE International Conference on Distributed Computing Systems (ICDCS 2017), Atlanta, Georgia, June 2017.

Storage and Memory Allocation

"Architecture of A Distributed Storage that Combines File System, Memory and Computation in A Single Layer" (with Jia Zou and Chris Jermaine). In The VLDB Journal, Volume 29, issue 5, September 2020. “Efficient Orchestration of Host and Remote Shared Memory for Memory Intensive Workloads” (with Juhyun Bae, Gong Su, Yanzhao Wu, and Ling Liu). In Proceedings of MEMSYS 2020: The International Symposium on Memory Systems., September 2020. "Assigning costs based on computer memory usage". US Patent 10,528,460, issued January 7, 2020, priority date September 22, 2010. This patent discloses new methods for dynamically allocating memory efficiently. A key aspect is charging users based on amounts of memory consumed in cloud and other multi-user environments. This patent is widely used in serverless computing. "Enhanced Clients for Data Stores and Cloud Services". In IEEE Transactions on Knowledge and Data Engineering vol. 31 no. 10, October 2019. "Pangea: Monolithic Distributed Storage for Data Analytics" (with Jia Zou and Chris Jermaine). In Proceedings of the 45th International Conference on Very Large Data Bases (VLDB 2019), Los Angeles, CA, August 2019. "Providing Enhanced Functionality for Data Store Clients". In Proceedings of the 33rd IEEE International Conference on Data Engineering (ICDE 2017), San Diego, California, April 2017. "Deferred Lightweight Indexing for Log-Structured Key-Value Stores" (with Yuzhe Tang, Wei Tan, Liana Fong, Ling Liu, and Balaji Palanisamy). Best Paper Award. In Proceedings of the 15th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing (CCGrid 2015), Shenzhen, Guangdong, China, May 2015.

I am interested in both main memory and persistent storage allocation. A major theme of my work in this area has been allocators which adapt themselves to request size distributions to optimize performance and minimize fragmentation. The first paper describes a disk storage allocation system which outperforms both file systems and databases for the workloads we used. This disk storage allocation system has been successful in several real deployments. The second paper presents main memory allocation algorithms which are particularly well suited for parallel computer systems.

"Techniques for Efficiently Allocating Persistent Storage" (with Shudong Jin and Jim Challenger). In Journal of Systems and Software vol. 68 #2, November 2003. "Scalability of Dynamic Storage Allocation Algorithms." In Proceedings of the Sixth IEEE Symposium on the Frontiers of Massively Parallel Computation (Frontiers '96), Annapolis, Maryland, October 1996.

Fault Tolerance and Replication

Failure Recovery in Resilient X10 (with multiple co-authors). In ACM Transactions on Programming Languages and Systems vol. 41 no. 3, July 2019. "VM-μCheckpoint: Design, Modeling, and Assessment of Lightweight In-Memory VM Checkpointing" (with Long Wang, Zbigniew Kalbarczyk, and Ravishankar Iyer). In IEEE Transactions on Dependable and Secure Computing vol. 12 no. 2, March/April 2015. “Resilient X10: Efficient failure-aware programming" (with David Cunningham, David Grove, Benjamin Herta, Kiyokuni Kawachiya, Hiroki Murata, Vijay Saraswat, Mikio Takeuchi, and Olivier Tardieu). In Proceedings of the 19th ACM Symposium on Principles and Practice of Parallel Programming (PPoPP 2014), Orlando, Florida, February 2014. "Avoiding Disruptive Failovers in Transaction Processing Systems with Multiple Active Nodes" (with Gong Su). In Journal of Parallel and Distributed Computing vol. 73 issue 5, May 2013. "A Highly Available Transaction Processing System with Non-Disruptive Failure Handling" (with Gong Su). In Proceedings of the 13th IEEE/IFIP Network Operations and Management Symposium (NOMS 2012), Maui, Hawaii, April 2012. "Dual-Quorum: A Highly Available and Consistent Replication System for Edge Services" (with Lei Gao, Mike Dahlin, Jiandan Zheng and Lorenzo Alvisi). In IEEE Transactions on Distributed and Secure Computing vol. 7 #2, April-June 2010. "Dual-Quorum Replication for Edge Services" (with Lei Gao, Mike Dahlin, Jiandan Zheng and Lorenzo Alvisi). In Proceedings of the ACM/IFIP/USENIX 6th International Middleware Conference (Middleware 2005), Grenoble, France, November/December 2005. "Thema: Byzantine-Fault-Tolerant Middleware for Web-Service Applications" (with Michael G. Merideth, Thomas Mikalsen, Stefan Tai, Isabelle Rouvellou and Priya Narasimhan). In Proceedings of the 24th IEEE International Symposium on Reliable Distributed Systems (SRDS 2005), Orlando, Florida, October 2005. "Improving Availability and Performance with Application-Specific Data Replication" (with Lei Gao, Mike Dahlin, Amol Nayate, and Jiandan Zheng). In IEEE Transactions on Knowledge and Data Engineering vol. 17 #1, January 2005. "Transparent Information Dissemination" (with Amol Nayate and Mike Dahlin). In Proceedings of ACM/IFIP/USENIX Middleware 2004, Toronto, Canada, October 2004. "Application Specific Data Replication for Edge Services" (with Lei Gao, Mike Dahlin, Amol Nayate, and Jiandan Zheng). Best Student Paper Award. In Proceedings of the 12th International World Wide Web Conference (WWW2003), Budapest, Hungary, May 2003. "Design and Implementation of a Secure Distributed Data Repository" (with Robert Cahn, Juan Garay, and Charanjit Jutla). In Proceedings of the 14th IFIP International Information Security Conference (SEC '98), Vienna, Austria and Budapest, Hungary, September 1998. "Software Exploitation of a Fault-Tolerant Computer with a Large Memory" (with Frank Eskesen, Michel Hack, Richard King, and Nagui Halim). In Proceedings of the 28th IEEE International Symposium on Fault-Tolerant Computing Systems, (FTCS '98), Munich, Germany, June 1998.

Security and Privacy

My work on Web load balancing with affinity between specific clients and servers (sticky load balancing) is critically important for Web sites which need to serve encrypted content at high rates.

“Location Privacy-preserving Mechanisms in Location-based Services: A Comprehensive Survey” (with Hongbo Jiang et al.). In ACM Computing Surveys, Volume 54, Issue 1, January 2021. “StackVault: Protection from Untrusted Functions” (with Qi Zhang et al.). In Proceedings of the Second IEEE International Conference on Trust, Privacy and Security in Intelligent Systems, and Applications (TPS 2020), December 2020. "A Trusted Healthcare Data Analytics Cloud Platform," (with Ashish Kundu, Upendra Sharma, and Ping Zhang). In Proceedings of the 38th IEEE International Conference on Distributed Computing Systems (ICDCS 2018), Vienna, Austria, July 2018. "Secure and Efficient Multi-Party Directory Publication for Privacy-Preserving Data Sharing" (with Katchaguy Areekijseree, Yuzhe Tang, Ju Chen, Shuang Wang, and Balaji Palanisamy). In Proceedings of the 14th EAI International Conference on Security and Privacy in Communication Networks (SecureComm 2018), Singapore, 2018 "e-PPI: Locator Service in Information Networks with Personalized Privacy Preservation" (with Yuzhe Tang, Ling Liu, Kisung Lee, and Qi Zhang). In Proceedings of the 34th IEEE International Conference on Distributed Computing Systems (ICDCS 2014), Madrid, Spain, June/July 2014. "EventGuard: A System Architecture for Securing Publish-Subscribe Networks" (with Mudhakar Srivatsa and Ling Liu). In ACM Transactions on Computer Systems vol. 29 no. 4, December 2011. "Privacy in VoIP Networks: Flow Analysis Attacks and Defense" (with Mudhakar Srivatsa, Ling Liu and Hongbo Jiang). In IEEE Transactions on Parallel and Distributed Systems vol. 22 no. 4, April 2011. "Scalable Key Management Algorithms for Location-Based Services" (with Mudhakar Srivatsa, Jian Yin, and Ling Liu). In IEEE/ACM Transactions on Networking vol. 17 no. 5, October 2009, pp. 1399-1412. "Mitigating Application-Level Denial of Service Attacks on Web Servers: A Client-Transparent Approach" (with Mudhakar Srivatsa, Jian Yin, and Ling Liu). In ACM Transactions on the Web vol. 2 No. 3, July 2008. "A Trust Management Framework for Service-Oriented Environments" (with William Conner, Thomas Mikalsen, Isabelle Rouvellou, and Klara Nahrstedt). In Proceedings of the 18th International World Wide Web Conference (WWW2009), Madrid, Spain, April 2009. "Preserving Caller Anonymity in Voice-over-IP Networks" (with Mudhakar Srivatsa and Ling Liu). In Proceedings of the 2008 IEEE Symposium on Security and Privacy, Oakland, CA, May 2008. "A Scalable Method for Access Control in Location-Based Broadcast Services" (with Mudhakar Srivatsa, Jian Yin, and Ling Liu). In Proceedings of IEEE INFOCOM 2008, Phoenix, AZ, April 2008. "An Access Control System for Web Service Compositions" (with Mudhakar Srivatsa, Thomas Mikalsen, Isabelle Rouvellou, and Jian Yin). In Proceedings of the IEEE 2007 International Conference on Web Services (ICWS 2007), Salt Lake City, Utah, July 2007. "A Middleware System for Protecting Against Application Level Denial of Service Attacks" (with Mudhakar Srivatsa, Jian Yin, and Ling Liu). In Proceedings of the ACM/IFIP/USENIX 7th International Middleware Conference (Middleware 2006), Melbourne, Australia, November/December 2006. "A Client-Transparent Approach to Defend Against Denial of Service Attacks" (with Mudhakar Srivatsa, Jian Yin, and Ling Liu). In Proceedings of the 25th IEEE International Symposium on Reliable Distributed Systems (SRDS 2006), Leeds, England, October 2006. "Design and Implementation of a Secure Distributed Data Repository" (with Robert Cahn, Juan Garay, and Charanjit Jutla). In Proceedings of the 14th IFIP International Information Security Conference (SEC '98), Vienna, Austria and Budapest, Hungary, September 1998.

Web Performance

The following papers provide a general overview of Web performance. "Improving Web Site Performance" (with Erich Nahum, Anees Shaikh, and Renu Tewari). In The Practical Handbook of Internet Computing, Copyright 2005, Chapman & Hall/CRC Press, Munindar P. Singh ed. "Web Caching, Consistency and Content Distribution" (with Erich Nahum, Anees Shaikh, and Renu Tewari). In The Practical Handbook of Internet Computing, Copyright 2005, Chapman & Hall/CRC Press, Munindar P. Singh ed. "Architecting Web Sites for High Performance" (with Daniela Rosu). In Scientific Programming, vol. 10 #1, June 2002. "High-Performance Web Site Design Techniques" (with Jim Challenger, Daniel Dias, and Paul Dantzig). In IEEE Internet Computing, vol. 4 #2, March/April 2000.

Mobile Computing, VoIP

"Cooperative Caching for Efficient Data Access in Disruption Tolerant Networks" (with Wei Gao, Guohong Cao, and Mudhakar Srivatsa). In IEEE Transctions on Mobile Computing vol. 13 no. 3, March 2014. "Design, Implementation, and Performance of a Load Balancer for SIP Server Clusters" (with Hongbo Jiang, Erich Nahum, Wolfgang Segmuller, Asser Tantawi, and Charles P. Wright). In IEEE/ACM Transctions on Networking vol. 20 no. 4, August 2012. "Byte Caching in Wireless Networks" (with Franck Le and Mudhakar Srivatsa). In Proceedings of the 32nd IEEE International Conference on Distributed Computing Systems (ICDCS 2012), Macau, June 2012. "Distributed Maintenance of Cache Freshness in Opportunistic Mobile Networks" (with Wei Gao, Guohong Cao, and Mudhakar Srivatsa). In Proceedings of the 32nd IEEE International Conference on Distributed Computing Systems (ICDCS 2012), Macau, June 2012. "Supporting Cooperative Caching in Disruption Tolerant Networks" (with Wei Gao, Guohong Cao, and Mudhakar Srivatsa). In Proceedings of the 31st IEEE International Conference on Distributed Computing Systems (ICDCS 2011), Minneapolis, Minnesota, June 2011. "Privacy in VoIP Networks: Flow Analysis Attacks and Defense" (with Mudhakar Srivatsa, Ling Liu and Hongbo Jiang). In IEEE Transactions on Parallel and Distributed Systems vol. 22 no. 4, April 2011. "ROADTRACK: Scaling Location Updates for Mobile Clients on Road Networks with Query Awareness" (with Peter Pesti, Ling Liu, Bhuvan Bamba, and Matt Weber). In Proceedings of the 36th International Conference on Very Large Data Bases (VLDB 2010), Singapore, September 2010. "Distributed Processing of Spatial Alarms: A Safe Region-based Approach" (with Bhuvan Bamba, Ling Liu, and Philip S. Yu). In Proceedings of the 29th IEEE International Conference on Distributed Computing Systems (ICDCS 2009), Montreal, Canada, June 2009. "Load Balancing for SIP Server Clusters" (with Hongbo Jiang, Erich Nahum, Wolfgang Segmuller, Asser Tantawi, and Charles P. Wright). In Proceedings of IEEE INFOCOM 2009, Rio de Janeiro, Brazil, April 2009. "Preserving Caller Anonymity in Voice-over-IP Networks" (with Mudhakar Srivatsa and Ling Liu). In Proceedings of the 2008 IEEE Symposium on Security and Privacy, Oakland, CA, May 2008.

Capacity Planning, Performance Modelling and Monitoring

I am interested in capacity planning, performance modelling, and monitoring for both scientific and commercial workloads. I have developed improved techniques for predicting customer workloads in the future from past behavior. This allows customers to estimate how much capacity will be required in the future. It also helps schedule tasks to optimize utilization of system resources and efficiently make use of spare CPU cycles in grid environments. Several of the techniques described in the papers in this section have been successfully used commercially.

"Volley: Violation Likelihood Based State Monitoring for Datacenters" (with Shicong Meng, Isabelle Rouvellou, and Ling Liu). In Proceedings of the 33rd IEEE International Conference on Distributed Computing Systems (ICDCS 2013), Philadelphia, PA, July 2013. "Reliable State Monitoring in Cloud Data Centers" (with Shicong Meng, Isabelle Rouvellou, Ling Liu, Kisung Lee, Balaji Palanisamy, and Yuzhe Tang). Best Paper Award. In Proceedings of the 5th IEEE International Conference on Cloud Computing (CLOUD 2012), Honolulu, Hawaii, June 2012. "EntomoModel: Understanding and Avoiding Performance Anomaly Manifestations" (with Christopher Stewart, Kai Shen, and Jian Yin). Best Paper Award. In Proceedings of the 18th IEEE International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems (MASCOTS 2010), Miami Beach, Florida, August 2010. "Capacity Planning Tools for Web and Grid Environments" (with Sugato Bagchi, Eugene Hung, Norbert Vogl, and Noshir Wadia). In Proceedings of the First International Conference on Performance Evaluation Methodologies and Tools (Valuetools 2006), Pisa, Italy, October 2006. "Commercial Applications of Grid Computing" (with Catherine Crawford, Daniel Dias, Marcos Novaes, and Li Zhang). Book chapter in Performance Analysis and Grid Computing, Kluwer Academic Publishers, 2003. "Analysis and Characterization of Large-Scale Web Server Access Patterns and Performance" (with Mark Squillante and Li Zhang). In World Wide Web vol. 2 #1, 2, June 1999.

Distributed Applications

"Design and Analysis of a Distributed Multi-leg Stock Trading System" (with Jia Zou, Gong Su, Yu Yuan, and Yi Ge). In Proceedings of the 31st IEEE International Conference on Distributed Computing Systems (ICDCS 2011), Minneapolis, Minnesota, June 2011. "Distributed Virtual Malls on the World Wide Web" (with Daniel Dias). In Proceedings of the 18th IEEE International Conference on Distributed Computing Systems (ICDCS '98), Amsterdam, Netherlands, May 1998. "Dynamic Argument Embedding: Preserving State on the World Wide Web". In IEEE Internet Computing, vol. 1 #2, March/April 1997.

Service-Oriented Computing

"Combining Quality of Service and Social Information for Ranking Services" (with Qinyi Wu, Revathi Subramanian, Isabelle Rouvellou, Ignacio Silva-Lepe, Thomas Mikalsen). In Proceedings of the 7th International Conference on Service Oriented Computing (ICSOC 2009), Stockholm, Sweden, November 2009. "A Trust Management Framework for Service-Oriented Environments" (with William Conner, Thomas Mikalsen, Isabelle Rouvellou, and Klara Nahrstedt). In Proceedings of the 18th International World Wide Web Conference (WWW2009), Madrid, Spain, April 2009. "SOAlive Service Catalog: A Simplified Approach to Describing, Discovering and Composing Situational Enterprise Services" (with Ignacio Silva-Lepe, Revathi Subramanian, Isabelle Rouvellou, Thomas Mikalsen, Judah Diament). In Proceedings of the 6th International Conference on Service Oriented Computing (ICSOC 2008), Sydney, Australia, December 2008. "An Access Control System for Web Service Compositions" (with Mudhakar Srivatsa, Thomas Mikalsen, Isabelle Rouvellou, and Jian Yin). In Proceedings of the IEEE 2007 International Conference on Web Services (ICWS 2007), Salt Lake City, Utah, July 2007. "Thema: Byzantine-Fault-Tolerant Middleware for Web-Service Applications" (with Michael G. Merideth, Thomas Mikalsen, Stefan Tai, Isabelle Rouvellou and Priya Narasimhan). In Proceedings of the 24th IEEE International Symposium on Reliable Distributed Systems (SRDS 2005), Orlando, Florida, October 2005.