We present a new and faster internal memory method to compute the drainage network, that is, the flow direction and accumulation on terrains represented by raster elevation matrix. The main idea is to surround the terrain by water (as an island) and then to raise the outside water level step by step, with depressions filled when the water reaches their boundary. This process avoids the very tim...

A run-time monitor is a program that runs in parallel with an untrusted application and examines actions from the application’s instruction stream. If the sequence of program actions deviates from a specified security policy, the monitor transforms the sequence or terminates the program. We present the design and formal specification of a language for defining the policies enforced by program m...

We present a framework for designing and composing services in a secure manner. Services can enforce security policies locally, and can invoke other services in a “call-by-contract” fashion. This mechanism offers a significant set of opportunities, each driving secure ways to compose services. We discuss how to correctly plan service orchestrations in some relevant classes of services and secur...

The performance of parallel linear algebra routines can be improved automatically using different methods. Our technique is based on the modellisation of the execution time of each routine, using information generated by routines from lower levels. However, sometimes the information generated at one level is not accurate enough to be used satisfactorily at higher levels. Therefore, a remodellin...

Service Oriented Computing (SOC) is a programming paradigm aiming at characterising Service Networks. Services are entities waiting for clients requests and they often result from the composition of many services. We address here the problem of statically guaranteeing security of open services, i.e. services with unknown components. Security constraints are expressed by local policies that serv...

The interest is on monitoring incoming space-time events to detect an emergent space-time cluster as early as possible. Assume that point process events are continuously recorded in space and time. In a certain unknown moment, a small localized cluster of increased intensity starts to emerge. Its location is also unknown. The aim is to let an alarm to go off as soon as possible after its emerge...