11 research outputs found
Towards Compensable SLAs
In Cooperative Information Systems, service level agreements (SLA) can be used to describe the rights and obligations of parties involved in the transaction (typically the service consumer and the service provider); amongst other information, SLA could define guarantees associated with the idea of service level objectives (SLOs) that normally represent key performance indicators of either the consumer or the provider. in case the guarantee is under-fulfilled or over-fulfilled SLAs could also define some compensations (i.e. penalties or rewards). in such a context, during the last years there have been important steps towards the automation of the management of SLAs, however the formalization of compensations in SLAs still remains as an important challenge. in this paper we aim to provide a characterization model to create SLAs with compensations; specifically, the main contributions are twofold: (i) the conceptualization of the Compensation Function to express consistently penalties and rewards and (ii) a model for Compensable Guarantees that associate SLOs with Compensation Functions. This formalization models aims to establish a foundation to elaborate tools that could provide an automated support to the modeling and analysis of SLAs with compensations. Additionally, in order to validate our approach, we model and analyze a set of guarantee terms from three real world examples of SLAs and our formalization proves to be useful for detecting mistakes that are ty
Edge and Cloud Pricing for the Sharing Economy
As technology resonates in all layers of society, the impulse of shifting toward new spaces for
a cooperative economy can be envisioned. Smart cities repre-sent an ideal laboratory to
design and explore new opportunities, offering a significant impact to citizens’ lives.Ministerio de EconomÃa y Competitividad TIN2015-70560-RJunta de AndalucÃa P12-TIC-186
Towards assessing open source communities' health using SOC concepts
Quality of an open source software ecosystem (OSS ecosystem) is key for different ecosystem actors such as contributors or adopters. In fact, the consideration of several quality aspects(e.g., activeness, visibility, interrelatedness, etc.) as a whole may provide a measure of the healthiness of OSS ecosystems. The more health a OSS ecosystem is, the
more and better contributors and adopters it will gather. Some research tools have been developed to gather specific quality information from open source community data sources. However, there exist no frameworks available that can be used to evaluate their quality as a whole in order to obtain the health of an OSS ecosystem. To assess the health
of these ecosystems, we propose to adopt robust principles and methods from the Service Oriented Computing field.Peer ReviewedPostprint (author's final draft
An Elasticity-aware Governance Platform for Cloud Service Delivery
In cloud service provisioning scenarios with a changing demand from consumers, it is appealing for cloud providers to leverage only a limited amount of the virtualized resources required to provide the service. However, it is not easy to determine how much resources are required to satisfy consumers expectations in terms of Quality of Service (QoS). Some existing frameworks provide mechanisms to adapt the required cloud resources in the service delivery, also called an elastic service, but only for consumers with the same QoS expectations. The problem arises when the service provider must deal with several consumers, each demanding a different QoS for the service. In such an scenario, cloud resources provisioning must deal with trade-offs between different QoS, while fulfilling these QoS, within the same service deployment. In this paper we propose an elasticity-aware governance platform for cloud service delivery that reacts to the dynamic service load introduced by consumers demand. Such a reaction consists of provisioning the required amount of cloud resources to satisfy the different QoS that is offered to the consumers by means of several service level agreements. The proposed platform aims to keep under control the QoS experienced by multiple service consumers while maintaining a controlled cost.Junta de AndalucÃa P12--TIC--1867Ministerio de EconomÃa y Competitividad TIN2012-32273Agencia Estatal de Investigación TIN2014-53986-RED
Automated Validation of Compensable SLAs
A Service Level Agreement (SLA) regulates the provisioning of a service by defining a set of guarantees. Each guarantee
sets a Service Level Objective (SLO) on some service metrics, and optionally a compensation that is applied when the SLO is
unfulfilled or overfulfilled. Currently, there are software tools and research proposals that use the information about compensations to
automate and optimise certain parts of the service management. However, they assume that compensations are well defined, which is
too optimistic in some circumstances and can lead to undesirable situations. In this article we discuss about the notion of validity of
guarantees with a compensation, which we refer to as compensable guarantees (CG). We describe an abstract model of CGs and we
provide a technique that leverages constraint satisfaction problem solvers to automatically validate them. We also present a
materialisation of the model of CGs in iAgree, a language to specify SLAs and a tooling support that implements our whole approach.
An assessment over 319 CGs taken from 24 real-world SLAs suggests that the expressiveness and effectiveness of our proposal can
pave the way for using CGs in a safer and more reliable way.Ministerio de EconomÃa y Competitividad BELI (TIN2015-70560-R)Ministerio de Ciencia, Innovación y Universidades TIN2016-81978-REDTJunta de AndalucÃa P12--TIC--186
Automated metamorphic testing of variability analysis tools
Variability determines the capability of software applications to be configured and customized. A common
need during the development of variability–intensive systems is the automated analysis of their underlying
variability models, e.g. detecting contradictory configuration options. The analysis operations that are
performed on variability models are often very complex, which hinders the testing of the corresponding
analysis tools and makes difficult, often infeasible, to determine the correctness of their outputs, i.e.
the well–known oracle problem in software testing. In this article, we present a generic approach for
the automated detection of faults in variability analysis tools overcoming the oracle problem. Our work
enables the generation of random variability models together with the exact set of valid configurations
represented by these models. These test data are generated from scratch using step–wise transformations
and assuring that certain constraints (a.k.a. metamorphic relations) hold at each step. To show the feasibility
and generalizability of our approach, it has been used to automatically test several analysis tools in three
variability domains: feature models, CUDF documents and Boolean formulas. Among other results, we
detected 19 real bugs in 7 out of the 15 tools under test.CICYT TIN2012-32273CICYT IPT-2012- 0890-390000Junta de AndalucÃa TIC-5906Junta de AndalucÃa P12-TIC- 186
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Automatic test case generation for WS-Agreements using combinatorial testing
In the scope of the applications developed under the service-based paradigm, Service Level Agreements (SLAs) are a standard mechanism used to flexibly specify the Quality of Service (QoS) that must be delivered. These agreements contain the conditions negotiated between the service provider and consumers as well as the potential penalties derived from the violation of such conditions. In this context, it is important to assure that the service based application (SBA) behaves as expected in order to avoid potential consequences like penalties or dissatisfaction between the stakeholders that have negotiated and signed the SLA. In this article we address the testing of SLAs specified using the WS-Agreement standard by means of applying testing techniques such as the Classification Tree Method and Combinatorial Testing to generate test cases. From the content of the individual terms of the SLA, we identify situations that need to be tested. We also obtain a set of constraints based on the SLA specification and the behavior of the SBA in order to guarantee the testability of the test cases. Furthermore, we define three different coverage strategies with the aim at grading the intensity of the tests. Finally, we have developed a tool named SLACT (SLA Combinatorial Testing) in order to automate the process and we have applied the whole approach to an eHealth case study
Service level agreement specification for IoT application workflow activity deployment, configuration and monitoring
PhD ThesisCurrently, we see the use of the Internet of Things (IoT) within various domains
such as healthcare, smart homes, smart cars, smart-x applications, and smart
cities. The number of applications based on IoT and cloud computing is projected
to increase rapidly over the next few years. IoT-based services must meet
the guaranteed levels of quality of service (QoS) to match users’ expectations.
Ensuring QoS through specifying the QoS constraints using service level agreements
(SLAs) is crucial. Also because of the potentially highly complex nature
of multi-layered IoT applications, lifecycle management (deployment, dynamic
reconfiguration, and monitoring) needs to be automated. To achieve this it is
essential to be able to specify SLAs in a machine-readable format.
currently available SLA specification languages are unable to accommodate
the unique characteristics (interdependency of its multi-layers) of the IoT domain.
Therefore, in this research, we propose a grammar for a syntactical structure
of an SLA specification for IoT. The grammar is based on a proposed conceptual
model that considers the main concepts that can be used to express the requirements
for most common hardware and software components of an IoT application
on an end-to-end basis. We follow the Goal Question Metric (GQM) approach to
evaluate the generality and expressiveness of the proposed grammar by reviewing
its concepts and their predefined lists of vocabularies against two use-cases
with a number of participants whose research interests are mainly related to IoT.
The results of the analysis show that the proposed grammar achieved 91.70% of
its generality goal and 93.43% of its expressiveness goal.
To enhance the process of specifying SLA terms, We then developed a toolkit
for creating SLA specifications for IoT applications. The toolkit is used to simplify
the process of capturing the requirements of IoT applications. We demonstrate
the effectiveness of the toolkit using a remote health monitoring service (RHMS)
use-case as well as applying a user experience measure to evaluate the tool by
applying a questionnaire-oriented approach. We discussed the applicability of our
tool by including it as a core component of two different applications: 1) a contextaware
recommender system for IoT configuration across layers; and 2) a tool for
automatically translating an SLA from JSON to a smart contract, deploying it
on different peer nodes that represent the contractual parties. The smart contract
is able to monitor the created SLA using Blockchain technology. These two
applications are utilized within our proposed SLA management framework for IoT.
Furthermore, we propose a greedy heuristic algorithm to decentralize workflow
activities of an IoT application across Edge and Cloud resources to enhance
response time, cost, energy consumption and network usage. We evaluated the
efficiency of our proposed approach using iFogSim simulator. The performance
analysis shows that the proposed algorithm minimized cost, execution time, networking,
and Cloud energy consumption compared to Cloud-only and edge-ward
placement approaches