Due to the increasing need of highly dependable services in Service-Oriented Architectures (SOA), service-level agreements include more and more frequently such traditional aspects as security, safety, availability, reliability, etc. Whenever a service can no longer be provided with the required QoS, the service requester need to switch dynamically to a new service having adequate service param...

Service availability is of key importance to operations and maintenance systems for mobile telephony networks. This paper will describe some of the challenges in providing continuous service and the impact of upgrade related outages. Potential methods for low outage upgrades will be discussed from an industrial perspective, including practical and logistic considerations.

Real-time micro-blogging services such as Twitter are widely recognized for their social dynamics — how they both encapsulate a social graph and propagate information across it. However, the content of this information is equally interesting since it frequently reflects individual experiences with a broad variety of real-time events. Indeed, events of broad interest are commonly revealed in cor...

Cryptography is the most suitable technique to protect the access to subscribed value-added services for mobile applications provided through satellite broadcasting (e.g. localization and mobile TV). However, if a temporary loss of signal is experienced by receivers, not only the data streaming is compromised, but also the key management-related messages. Hence, when the signal is received agai...

We describe an ambulance location optimization model that minimizes the number of ambulances needed to provide a specified service level. The model measures service level as the fraction of calls reached within a given time standard and considers response time to be composed of a random delay (prior to travel to the scene) plus a random travel time. In addition to modeling the uncertainty in th...

Monitoring has become one of the key issues for the successful deployment of IP multicast in the Internet. During the last decade, several tools and systems have been developed to monitor several different characteristics of IP multicast. In this paper, we focus on one specific monitoring task: monitoring end-to-end multicast service availability in the inter-domain. This task is important to m...

This paper presents a prediction model for software service availability measured by the mean-time-to-repair (MTTR) and mean-time-to-failure (MTTF) of a service. The prediction model is based on the experimental identification of probability distribution functions for variables that affect MTTR/MTTF and has been implemented using a framework that we have developed to support monitoring and pred...

Data availability is one of the most important properties of peer-to-peer (P2P) storage systems. Availability analysis model and data placement are two key design choices. Users in P2P storage system are both providers and customers. This characteristic determines that the availability analysis must be user-centric, and thereby enhance the quality of service and decrease the system cost. The po...

Demand response provides utilities with a mechanism to share with end users the stochasticity resulting from the use of renewable sources. Pricing is accordingly used to reflect energy availability, to allocate such a limited resource to those loads that value it most. However, the strictly competitive mechanism can result in service interruption in presence of competing demand. To solve this i...