Section: New Results

Self-Configuration of distributed system in the Cloud

Participants : Fabienne Boyer, Noël de Palma.

Cloud computing environments fall under three main kinds of offers according to the resources they provide. The Infrastructure as a Service (IaaS) level enables the access to virtualized hardware resources (processing, storage and network). The Software as a Service (SaaS) layer aims at providing the end-users with software applications. The intermediary layer, called Platform as a Service (PaaS), offers a set of tools and runtime environments that allow managing the applications life-cycle. This life-cycle includes the phases related to the design, the development, the deployment of applications, and generally speaking all their management stages (workload, fault tolerance, security). This article focuses on the deployment of distributed applications in virtualized environments such as cloud computing. Such deployments require to generate the virtual images that will be instantiated as virtual machines, thus ensuring the execution of the application on an IaaS platform. Each image embeds technical elements (operating system, middleware pieces) and functional ones (data and applicative software entities). Once it has been instantiated, each virtual machine is subjected to a stage of dynamic settings, which finalizes the global configuration of the distributed application.

On the whole, the deployment solutions currently available do not take into account these different configuration parameters, which are mostly managed by dedicated scripts. Moreover these solutions are not able to automate the images generation, their instantiation as virtual machines and their configuration independently from the kind of distributed application to be deployed. For instance, Google App Engine solution only deals with Web services organized into precisely defined tiers. In our opinion, the absence of general solutions results essentially from a lack of formalism for describing the distributed application architecture with its configuration constraints in a virtualized infrastructure such as cloud computing. Pour work focused on a general solution, for Virtual Applications Management Platform, that automates the deployment of any distributed applications in the cloud. The suggested approach is architectural, meaning that it is based upon an explicit representation of the applications’ distributed architecture. We offer, on the one hand, a formalism for describing an application as a set of interconnected virtual machines and, on the other hand, an engine for interpreting this formalism and automating the application deployment on an IaaS platform. Specifically, we study three contributions:

• A formalism that offers a global view of the application to be deployed in terms of components with the associated configuration- and interconnection constraints and with their distribution within virtual machines. This formalism extends OVF language, dedicated to virtual machines description, with an architecture description language (ADL) that allows describing a distributed application software architecture;

• A deployment engine, i.e. a runtime support able to deploy automatically an application described with this formalism. This engine is based on a decentralized protocol for self-configuring the instantiated virtual machines. In our opinion it can ease the scalability of the dynamic configuration stage;

• A performance evaluation of the proposed solution on an industrial IaaS platform.

We published in this context two journal articles (TPDS [26] and TAAS [18] ) and three conference papers (Cloud11 [35] , UCC11 [39] and SAC12).