Towards Cloud Application Description Templates Supporting Quality of Service

Typical scientific, industrial and public sector applications require resource scalability and efficient resource utilization in order to serve a variable number of customers. Cloud computing provides an ideal solution to support such applications. However, the dynamic and intelligent utilization of cloud infrastructure resources from the perspective of cloud applications is not trivial. Although there have been several efforts to support the intelligent and coordinated deployment, and to a smaller extent also the run-time orchestration of cloud applications, no comprehensive solution has emerged until now that successfully leverages large scale near operational levels and ease of use. COLA is a European research project to provide a reference implementation of a generic and pluggable framework that supports the optimal and secure deployment and run-time orchestration of cloud applications. Such applications can then be embedded into workflows or science gateway frameworks to support complex application scenarios from user-friendly interfaces. A specific aspect of the cloud orchestration framework developed by COLA is the ability to describe complex application architectures incorporating several services. Besides the description of service components, the framework will also support the definition of various Quality of Service (QoS) parameters related to performance, economic viability and security. This paper concentrates on this latter aspect analysing how such application description templates can be developed based on existing standards and technologies

Modelling the behaviour of management operations in cloud-based applications

How to flexibly manage complex applications over heterogeneous clouds is one of the emerging problems in the cloud era. The OASIS Topology and Orchestration Specification for Cloud Applications (TOSCA) aims at solving this problem by providing a language to describe and manage complex cloud applications in a portable, vendoragnostic way. TOSCA permits to define an application as an orchestration of nodes, whose types can specify states, requirements, capabilities and management operations — but not how they interact each another. In this paper we first propose how to extend TOSCA to specify the behaviour of management operations and their relations with states, requirements, and capabilities. We then illustrate how such behaviour can be naturally modelled, in a compositional way, by means of open Petri nets. The proposed modelling permits to automate different analyses, such as determining whether a deployment plan is valid, which are its effects, or which plans allow to reach certain system configurations

Finding available services in TOSCA-compliant clouds

The OASIS TOSCA specification aims at enhancing the por-ta-bility of cloud applications by defining a language to describe and manage them across heterogeneous clouds. A service template is defined as an orchestration of typed nodes, which can be instantiated by matching other service templates. In this paper, we define and implement the notions of {em exact} and {it plug-in matching} between TOSCA service templates and node types. We then define two other types of matching ({em flexible} and {em white-box}), each permitting to ignore larger sets of non-relevant syntactic differences when type-checking service templates with respect to node types. The paper also describes how a service template that plug-in, flexibly or white-box matches a node type can be suitably adapted so as to exactly match it

Persistence and discovery of reusable cloud application topologies

Due to the benefits introduced by the Cloud computing paradigm and the increase of available Cloud services (VM- and non VM-oriented), in the last years the number of application developers strongly supporting a partial or complete migration of application component to Cloud environments has significantly increased. For example, it is possible to host the application's database off-premise (e.g. in a DBaaS solution) while keeping the remaining components (presentation or business logic components) on-premise. However, the previous application deployment is only one possible distribution alternative, and the existence of further alternatives allows the generation of a wide variety of distribution combinations. In addition, the challenges for application developers to efficiently select optimal strategy of application's deployment by considering evolving application performance with fluctuating workload has increased rapidly. How to select, configure and deploy an application optimally to satisfy functional and non-functional requirements of business and operation has been a research area in both academic and industry domains. In this Master thesis, basing on the approaches proposed in previous work, we first conduct a research on existing approaches and technologies about how to persist, retrieve and build typed graph-based Cloud application topologies leveraging the benefits introduced and developed in graph databases and graph database technologies, respectively. Consequently, we develop the core algorithms for persisting and discovering application topologies focusing on their similar characteristics. Such conceptual models relate to the required structural aspects representing the relationship between the application topologies, their performance aspects, and their evolving workload. As a result of this thesis, a prototypical implementation of a RESTful-based framework to support discovering and building reusable viable topologies of Cloud application w.r.t. evolving functional and non-functional aspects is provided, e.g. taking into account its performance, its corresponding profile and its corresponding evolving workload

Reusing cloud-based services with TOSCA

The OASIS TOSCA specification [OAS13b] aims at enhancing the portability and interoperability of cloud-based applications by providing a language to describe and manage them across heterogeneous clouds. A cloud-based application is modelled by a service template, an orchestration of typed nodes which can be in turn instantiated by matching [BS13] other service templates. In this paper we present a methodology to non-intrusively adapt a service template S into a new service template newS which exactly matches a node type N, and hence to easily reuse any actual service modelled by S to deploy cloud-based applications that rely on N