Section: New Results

System configuration and deployment

Participants : Loris Bouzonnet, Fabienne Boyer, Willy Malvault, Noël de Palma, Vivien Quéma, Jean-Bernard Stefani.

The goal of this work is to study system configuration and software deployment issues in large distributed systems.

System configuration and software deployment in a distributed environment can be greatly aided by the use of a uniform component model to support software assembly, software configuration and deployment, as well as runtime system configuration. We have developed a specialization of the Fractal component model that provides a reference model for heterogeneous software assembly and configuration. In particular, we have shown how this reference model can be used to assemble and configure software architectures built from heterogeneous software packages (e.g. OSGI bundles for Java packages, Debian or RPM packages for Linux modules and applications). The definition of this model, a description of its implementation and its evaluation are documented in Loris Bouzonnet's PhD thesis [13] .

As an alternative to current public cloud infrastructures, which rely on large data centers, we have started the study of a cloud infrastructure based on a peer-to-peer (P2P) overlay network built on gossip-based protocols. More precisely, we have studied how to implement a distributed resource allocation service in a P2P environment maintained by a gossip-based peer-sampling protocol [81] . The resulting system, called Salute, provides for the allocation of application-specific overlays out of an underlying P2P network. By combining several P2P services (including peer-sampling, topology maintenance, and node synchronization), and by partitioning available nodes into free nodes (available for the allocation of new application overlays) and reserve nodes (nodes dedicated to the maintenance of allocated overlays), Salute provides a churn-resilient, completely decentralized cloud infrastructure. In addition, we have shown that Salute can provide its allocation service while maintaining fairness and avoiding starvation. The Salute architecture has been validated through simulations using network traces from different real-worl P2P environments. The Salute architecture, algorithms and their validation are documented in Willy Malvault's PhD thesis [14] .

In a cloud computing context the complexity of deploying and configuring non-trivial software architectures is exacerbated. In line with our previous work on architecture-based distributed system management, we have proposed a novel algorithm for configuring component-based distributed applications deployed within several virtual machines in an IaaS environment. The algorithm is completely decentralized, relies on a message queuing middleware and exploits the software architecture descriptions of the applications to deploy and configure, written in an extension of the Fractal Architecture Description Language. A first version of this algorithm, that does not take into account potential failures during the configuration process, has been formally specified in collaboration with Gwen Salaün from the INRIA Vasy team in Grenoble, and presented at IEEE Cloud 2011 [35] .