ABSTRACT. Software-as-a-Service (SaaS) providers increasingly rely on multi-cloud setups to leverage the combined benefits of different enabling technologies and third-party providers. Especially, in the context of NoSQL storage systems, which are characterized by heterogeneity and quick technological evolution, adopting the multi-cloud paradigm is a promising way to deal with different data storage requirements. Existing data access middleware platforms that support this type of setup (polyglot persistence) commonly rely on (i)~configuration models that describe the multi-cloud setup, and (ii)~the hard-coded logic in the application source code or the data storage policies that define how the middleware should store data across different storage systems.

In practice, however, both models are tightly coupled, i.e.~the storage policies refer to specific configuration model elements, leads to fragility issues (ripple effects) and hinders reusability. Especially in multi-cloud configurations that change often (e.g.,~in dynamic cloud federations), this is a key problem.

In this paper, we present a more expressive way to specify storage policies, that involves (i)~enriching the configuration models with metadata about the technical capabilities of the storage systems, (ii)~referring to the desired capabilities of the storage system in the storage policies, and (iii)~leaving actual resolution to the policy engine.

Our validation is done in the context of a realistic SaaS application, in which we show for a number realistic policy change scenarios how the policies accommodate such changes. We also evaluate the performance impact in order to investigate the performance overhead of our approach.

ABSTRACT. The perception of lack of control over resources deployed in the cloud may represent one of the critical factors for an organization to decide to cloudify or not their own services. Furthermore, in spite of the idea of offering security-as-a-service, the development of secure cloud applications requires security skills that can slow down the adoption of the cloud for those not expert users. In the recent years, the concepts of Security Service Level Agreements (Security SLA) is assuming a key role in the provisioning of cloud resources and it has become of primary importance for standardization bodies, too. In this paper we present the SPECS framework, which enables the development of secure cloud applications covered by a Security SLA. The SPECS framework offers APIs to manage the whole Security SLA life cycle (namely, the Negotiation, Enforcement, Monitoring, Remediation and Re-negotiation phases) and provides all functionalities needed to automatize the enforcement of proper security mechanisms and monitoring systems to respectively provide and monitor user security features. In particular, we will illustrate the process of developing SPECS applications devoted to offering security-enhanced services, and we will present a real-world case study related to the provisioning of a secure web server.

ABSTRACT. Recently we witnessed a deep transformation in the the design, development and management of modern applications, which have grown in scope and size becoming distributed and service-oriented. A big part in this metamorphosis is played by the Cloud with the availability of almost-infinite resources, high availability and outsourced maintenance. This has led to the emergence of new software development methodologies to effectively deal with this paradigm shift in the field of software engineering. DevOps is one of them, it advocates for a greater level of collaboration and convergence between developers and other IT professionals. Consequently, new tools, purposely designed to ease this process, are required. In this scenario, we present SPACE4Cloud, a DevOps integrated environment for model-driven design-time quality of service assessment and optimization, and runtime capacity allocation of Cloud applications.

ABSTRACT. In a general purpose cloud system efficiencies are yet to be had from supporting diverse application requirements within a heterogeneous storage system. Such a system poses signif- icant technical challenges since storage systems are traditionally homogeneous. This paper uses the Ceph distributed file system, and in particular its concept of storage pools, to show how a storage solution can be partitioned to provide the heterogeneity needed to support the required application requirements.

ABSTRACT. In his paper we make a short overview of current state of the art monitoring tools for both cloud and big data frameworks. A hot topic for research in recent years is manipulation of big data, cloud computing and a combination of them. The focus on these topics is due to the problems that are posed by the manipulation of big data in cloud environments as well as the potential that they expose for obtaining better results. However, in order to effectively create, test and de- ploy new algorithms or frameworks one needs also suitable monitoring solutions. In this paper we aim on creating a critical overview for some of the most important monitor- ing solutions existing on the market. Besides that we also present the relevant metrics used for monitoring the cloud as well as big data applications, with the focus on cloud deployment scenarios for big data frameworks.