  Multimedia conferencing is used extensively in a wide range of applications,
such as online games and distance learning. These applications need to
efficiently scale the conference size as the number of participants fluctuates.
Cloud is a technology that addresses the scalability issue. However, the
proposed cloud-based solutions have several shortcomings in considering the
future demand of applications while meeting both Quality of Service (QoS)
requirements and efficiency in resource usage. In this paper, we propose an
Adaptive and Dynamic Scaling mechanism (ADS) for multimedia conferencing
services in the cloud. This mechanism enables scalable and elastic resource
allocation with respect to the number of participants. ADS produces a
cost-efficient scaling schedule while considering the QoS requirements and the
future demand of the conferencing service. We formulate the problem using
Integer Linear Programming (ILP) and design a heuristic for it. Simulation
results show that ADS mechanism elastically scales conferencing services.
Moreover, the ADS heuristic is shown to outperform a greedy algorithm from a
resource-efficiency perspective.
