Specifying Semantic Interoperability between Heterogeneous Cloud Resources with the FCLOUDS Formal Language

International audienceWith the advent of cloud computing, different cloud providers with heterogeneous services and Application Programming Interfaces (APIs) have emerged. Hence, building an interop-erable multi-cloud system becomes a complex task. Our idea is to design FCLOUDS framework to achieve semantic interoperability in multi-clouds, i.e., to identify the common concepts between cloud APIs and to reason over them. In this paper, we propose to take advantage of the Open Cloud Computing Interface (OCCI) standard and the Alloy formal specification language to define the FCLOUDS language, which is a formal language for specifying heterogeneous cloud APIs. To do so, we formalize OCCI concepts and operational semantics, then we identify and validate five properties (consistency, sequentiality, reversibility, idempotence and safety) that denote their characteristics. To demonstrate the effectiveness of our cloud formal language, we present thirteen case studies where we formally specify infrastructure, platform, Internet of Things (IoT) and transverse cloud concerns. Thanks to the Alloy analyzer, we verify that these heterogeneous APIs uphold the properties of FCLOUDS and also validate their own specific properties. Then, thanks to formal transformation rules and equivalence properties, we draw a precise alignment between our case studies, which promotes semantic interoperability in a multi-cloud system

Model driven simulation of elastic OCCI cloud resources

International audienceDeploying a cloud configuration in a real cloud platform is mostly cost-and time-consuming, as large number of cloud resources have to be rent for the time needed to run the configuration. Thereafter, cloud simulation tools are used as a cheap alternative to test Cloud configuration. However, most of existing cloud simulation tools require extensive technical skills and does not support simulation of any kind of cloud resources. In this context, using a model-driven approach can be helpful as it allows developers to efficiently describe their needs at a high level of abstraction. To do, we propose, in this article, a Model-Driven Engineering (MDE) approach based on the OCCI (Open Cloud Computing Interface) standard metamodel and CloudSim toolkit. We firstly extend OCCI metamodel for supporting simulation of any kind of cloud resources. Afterward, to illustrate the extensibility of our approach, we enrich the proposed metamodel by new simulation capabilities. As proof of concept, we study the elasticity and pricing strategies of Amazon Web Services (AWS). This article benefits from OCCIware Studio to design an OCCI simulation extension and to provide a simulation designer for designing cloud configurations to be simulated. We detail the approach process from defining an OCCI simulation extension until the generation and the simulation of the OCCI cloud configurations. Finally, we validate the proposed approach by providing a realistic experimentation to study its usability, the resources coverage rate and the cost. The results is compared with the ones computed from AWS

OCCI-Compliant Cloud Configuration Simulation

In recent years many organizations such as, Amazon, Google, Microsoft, have accelerated the development of their cloud computing ecosystem. This rapid development has created a plethora of cloud resource management interfaces for provisioning, supervising, and managing cloud resources. Thus, there is an obvious need for the standardization of cloud resource management interfaces to cope with the prevalent issues of heterogeneity, integration, and portability issues.To this end, Open Cloud Computing Interface (OCCI) proposed one of the first widely accepted, community-based, open standard for managing any kinds of cloud resources. However, there is a strong need for having a simulation environment to study and analyze the performance of OCCI-compliant applications for two main reasons: (i) in absence of a simulation environment, these applications have to be tested on real cloud infrastructure, which induces a cost issue and (ii) various conditions prevailing in cloud environments are beyond the control of the developers involved in analyzing cloud resource allocation. Therefore, in this paper we propose, (i) an extension to the OCCI metamodel dedicated to the simulation of cloud resources using an open-source cloud simulation framework called CloudSim, (ii) a user-friendly graphical interface to generate the OCCI configuration for simulation