Improving Performance and Reliability in Internet Services

Although Internet infrastructure has become a main stream technology, providing important services for the human society, there are still performance and reliability issues to address. We are conducting several related research projects, aiming at improving quality of Web servers, proxy services, and Distributed Name System (DNS).

Web Service and Proxy Performance Improvement

Representative Publications:

• X. Chen and X. Zhang, ``A popularity-based prediction model for Web prefetching", IEEE Computer, Vol. 36, No. 3, March, 2003.

• X. Chen and X. Zhang, ``Coordinated data prefetching for Web contents", Computer Communications, Vol. 28, Issue 17, October 2005.

• S. Chen and X. Zhang, ``Enforcing direct communications between clients and Web servers to improve proxy performance and security", Software: Practice and Experience, Vol. 34, Issue 12, October 2004.

Maintaining Strong Cache Consistency in Domain Name System (DNS)

The Domain Name System (DNS) is a global-scale distributed database that provides a fundamental directory service for Internet users and applications. As an indispensable component of the Internet infrastructure, DNS consists of a hierarchy of nameservers, translating domain names to IP addresses. For such a hierarchical system, effectiveness and timeliness of caching are critical to the scalabilty and performance of DNS. However, existing DNS only supports weak cache consistency by using the Time-to-Live (TTL) mechanism. To deal with sudden and dramatic Interent failure problems caused by natural and human disasters, such as flooding, hurricane, and physical attacts to Interent, DNS needs to quickly propagate a changed DNS resource record, otherwise, service availability of the record will be lost. Without maintaining strong consistency among DNS nameservers, the excpetional failure cases in Internet will not be handled well due to the DNS cache inconsistency. We believe this is a serious loophope in DNS, which can threaten the availability and reliability of Interent services when sudden and dramatic changes happen in the Interent. We propose to establish strong cache consistency for DNS as an exceptional handler.

Representative Publications:

• X. Chen, H. Wang, S. Ren, and X. Zhang, ``DNScup: a strong cache consistency protocol for DNS", Proceedings of International Conference on Distributed Computing Systems (ICDCS'06), Lisbon, Portugal, July 4-7, 2006.