Cloud Infrastructure as a Service (IaaS) Service Level Agreements (SLAs) assessment consist a major, well-established and widely adopted way of services descriptions when it comes to public cloud infrastructure. The SLA assessment always follows and monitors the compliance level of the infrastructure providers promised services to their clientele experience. On the other hand, the corresponding ways that this compliance is evaluated and validated in Public Cloud have created a grey layer of ambiguity to the level of accuracy and verification of the respective SLAs.

In fact, the ownership of the majority of the available public cloud resources is found between a few mammoth corporations. Therefore, the providing of public cloud services tends to the creation of a monopoly market where the interested consumers participate as clients and acquire the offered products. In order to formulate a fairer and more transparent scheme of SLA assessment, Pledger introduces the concept of full decentralization with innate privacy of transactions under the umbrella of blockchains.

Pledger studies the mechanics of SLA self-assessment by proposing the employable business intelligence of SLA compliance in the context of blockchain transactional and contractual privacy[1]. In this context, the dedicated SLA assessment ecosystem is based on a permissioned blockchain network where the IaaS and their corresponding clientele participate. The suggested end-to-end scenario introduces SLA monitoring and computation processes that are executed isolated within the blockchain.

Particularly, in the beginning of the scenario, both the IaaS and their clientele agree on a common SLA that describes in an accurate and transparent way the dedicated services of the business relationship. The SLA description is submitted on the blockchain and includes the respective SLA monitoring and computation regulations that specify the SLA assessment procedure. Therefore, an SLA purchase already defines beforehand on the blockchain the dedicated rules and algorithmic drivers that contribute in the SLA assessment process. Furthermore, the defined SLA monitoring and computation executions occur inside dedicated Trusted Execution Environments (TEEs) that are installed on the blockchain ledger. The TEEs offer a significant novelty in the SLA assessment procedure as per their enclaved environments executions. The SLA monitoring and computations happen inside the dedicated enclaves and their actual process is isolated from other blockchain entities bringing privacy and transparency on the ledger. When an SLA product is purchased, the Pledger proposed mechanism constantly audits the corresponding metrics as defined per the respective SLA while the decentralized network completes the SLA assessment procedure automatically. Accordingly, the entire process unfolds on the blockchain network with the respective additional privacy features.

Pledger presents an end-to-end holistic ecosystem where the SLA assessment occurs in automation, namely SLA self-assessment, and without the direct involvement of the IaaS in the process. The contribution of Pledger in the public cloud infrastructure and the Cloud IaaS SLAs workflows constitutes a novel approach in the SLA assessment field that eliminates the respective monopoly landscape and enhances precision and computational justice of SLAs within the Public Cloud.


[1]    Kapsoulis, N.; Psychas, A.; Litke, A.; Varvarigou, T. Reinforcing SLA Consensus on Blockchain. Computers 2021, 10, 159.   


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