Service Level Guarantees For Clustered Web Services

Alaa Youssef

Abstract

Web services are self-contained software components that are published,
located, and invoked over the Internet or an intranet, using standard protocols
and interfaces. For example, the Web services architecture allows an
application at one company to query a service at another company to determine
the current price of a particular product. Using standard enabling
technologies, an application or service can be made available over the network
without regard to platform, language, location, or implementation of the
service.

In this talk we will present an architecture and describe the prototype
implementation of a performance management system for cluster-based web
services. The system supports multiple classes of web services traffic and
allocates server resources dynamically in order to maximize the expected value
of a given cluster utility function in the face of fluctuating loads.  The
cluster utility is a function of the performance delivered to the various
classes, and this leads to differentiated service. We use the average response
time as the performance metric. The management system is transparent: it
requires no changes in the client code, the server code, or the network
interface between them. The system performs three performance management tasks:
resource allocation, load balancing, and server overload protection.

We use a two-level management approach.  The inner level centers on queuing and
scheduling of request messages.  The outer level is a feedback control loop
that periodically adjusts the scheduling weights and server allocations of the
inner level. The feedback controller is based on an approximate
first-principles model of the system, with parameters derived from continuous
monitoring. We focus on SOAP-based web services. We report experimental results
that show the dynamic behavior of the system.

Speaker's Biography

Alaa Youssef is a Research Staff Member at IBM T.J. Watson Research
Center. He is currently a member of the Service Management Middleware
group. He joined IBM Research in 1998. In 2003, he took a one-year leave
from IBM and joined the faculty at Alexandria University, Alexandria,
Egypt. He received his PhD degree in computer science in 1998 from
Old Dominion University, Virginia. His advisers were Prof. Hussein
AbdelWahab and Prof. Kurt Maly. He received his BS and MS degrees in
computer science and automatic control from Alexandria University, Egypt,
in 1991 and 1994, respectively.

His research interests include distributed systems, service management
middleware, network and application level quality of service, content security
and digital rights management. He has over 25 refereed journal and conference
publications, 2 issued patents and 8 more pending with the US Patent and
Trademark Office. Dr. Youssef is a member of the IEEE. He served on the
technical and executive committees of several IEEE and ACM conferences,
including INFOCOM, CSCW, and MMNS.