DISI Dipartimento di Informatica e Scienze dell'Informazione


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Distributed and Object Oriented Systems

Index



The Team

Faculty:
Massimo Ancona, Giovanni Chiola, Gabriella Dodero, Vittoria Gianuzzi
Postgraduates:
Giuseppe Ateniese, Ruben Carvajal, Giuseppe Ciaccio

Projects



Research Activities

The activities are concerned about the study, implementation and performance evaluation of distributed and object oriented systems. Some aspects related to the implementation of object oriented languages are considered as well. Implementation issues, and efficiency of the implementation are the primary goals of the research.
Object Oriented Languages
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Active Messages ( G. Chiola, G. Ciaccio)
This can be described as a "RISC-like" approach to interprocess communication in asynchronous SPMD or MIMD type distributed systems. The reference model consists of sets of asynchronous processes running on different processors according to a local scheduling policy for each processor. Processors are connected by fast local area networks, and a process running on a processor may send messages to processes running on different processors by accessing the raw hardware controllers of the network devices with a minimal operating system overhead. Messages are "active" in the sense that the reception of a message on a node triggers the execution of a handler on the receiver processor, and the code of the handler is provided by the application programmer. Low latency and high throughput are the main benefits of the approach as compared to the "CISC-like" approach to communication that is usually provided by standard Operating System communication primitives such as UNIX sockets. The GAMMA project has been started to experiment with efficient implementations of the concept using a low-cost distributed platform composed of Pentium workstations connected by 100 Mb/s Fast Ethernet.

PVM and MPI
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Performance modelling and Simulation ( G. Chiola)
The derivation and numerical evaluation or computer simulation of behavioural models is one of the main techniques to study the performance of complex, distributed systems in the design phase, before a prototype is available for actual measurements. Stochastic Petri nets are one of the more powerful tools for modelling asynchronous distributed systems. The efficiency of analysis and simulation algorithms to study large stochastic Petri net models is a key issue for the applicability of the modelling and simulation technique to real cases of distributed systems whose performance would be interesting to study. Giovanni Chiola has long been involved in the development of the GreatSPN tool for stochastic Petri net analysis and simulation, as well as in the use of such tool to study the performance of distributed systems, both at the hardware and at the system software level.

Security and Electronic Commerce ( G. Ateniese, G. Chiola)
The demand for secure and efficient electronic commerce (EC) applications is growing, not only for large business transactions for small and diffused business. The traditional approach based on value-added networks (VANs) is inadequate to satisfy such a growing demand due to their excessive costs and planning complexity as well as their lack of diffused connectivity. The use of Internet instead of VANs would allow the widespread diffusion of EC applications among common people. Unfortunately, the use of current Internet protocols involves a number serious drawbacks, such as the lack of reliability, scalability and security. In this context we are studying the problem of producing secure Internet applications aimed to the use in small business environments. Our first goal is the design of a suite of highly secure key distribution, authentication and other protocols for group communication. Our second goal is the design and prototype implementation of an Internet payment protocol. In the medium term perspective, we are also planning to study the feasibility of the porting of the payment protocol to a mobile digital telephone system environment.



External collaborations



Please send suggestions and comments to:
Giovanni Chiola chiola@disi.unige.it
Last Updated: 27 Jul, 1997