Istituto di Scienza e Tecnologie dell'Informazione     
Coppola M., Dazzi P., Carlini E., Righetti G., et al. .. CONTRAIL - Architecture design and QoS constraints matching algorithms in Federations. OPEN COMPUTING INFRASTRUCTURES FOR ELASTIC SERVICES. Deliverable D2.2, 2011.
This deliverable analyses both functionality and algorithms for Contrail Federations and provides an architectural design which takes into account aspects of Identity management and Security. The Federation plays a central role in Contrail: users access Contrail resources through the Federation, which is one the main selling points of Contrail. A Federation can be seen as a bridge between cloud users and cloud providers, since it mediates between users' requests and providers owning the resources. The document starts with an overview of the key functionality offered by a Federation; then it introduces a model describing the relationships between the entities involved in a Federation. The analysis takes into account aspects of security, administration of user identities and management of cloud providers, as well as tracing those aspects and functions to the requirements gathered in the first phase of the Contrail project. In the final release, the Contrail Federation will manage multiple providers, possibly including external cloud providers such as Amazon and Azure. The analysis of the coordination of different cloud providers by means of their SLA is not a trivial problem and it requires the utilization of optimization algorithms. For this reason, as implementing all the functionality at once is not realistic, two different scenarios - a basic one and an advanced one - have been identified; the two Federation prototypes to be released according to the Description of Work aim at implementing those two scenarios. The Federation architecture is discussed from different perspectives: a static view showing Federation layers and internal components, a dynamic view showing the interactions between modules and a deployment view showing how software components are deployed into available hardware. In the analysis of Federation algorithms, a big issue is the management of SLAs on different cloud providers. The difficulty comes from the fact that a Federation is not just a simple broker, but plays an active role and mediates between the aims of the final user and those of the set of providers. A Federation, in addition, may be seen itself as a provider. Once understood the real added value offered by the Federation in a cloud ecosystem, it becomes apparent that a Federation may also be a business entity earning money from its services. This implies that a Federation should also handle typical business issues, such as risk management, for being profitable. For instance, when a SLA is split between several providers, the Federation must manage prices but also penalties, both with users and providers: a SLA violation from a provider may result in an economic loss for the Federation. Finally, flexibility and usability of the interfaces play a critical role in a Cloud, hence they also do in Contrail Federations. Three different kinds of interfaces have been defined: a graphical web User Interface, a REST interface and a command-line interface. In CONTRAIL, the same REST interface could be used to access both providers and the Federation, thus simplifying the overall implementation, and allowing for all standard interfaces (e.g. OCCI) to be laid on top of both. A further advantage is in the opportunity to compose Federations and providers in a transparent way, allowing to exploit the Federation as a single cloud provider. As already pointed out in D2.1, WP2 activities intrinsically overlap with other work packages, especially WP3, WP7 and WP10; Federation details on topics discussed in other deliverables are properly referenced in this document.
Subject Cloud Computing
Distributed System
C.1.1 Single Data Stream Architectures
C.5.1 Large and Medium (``Mainframe'') Computers

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