–CONF inspirations to the traditional cloud industry

“Over the last few years, the decentralized cloud market has emerged with the goal to displace public cloud service providers with cheaper, more secure blockchain-based compute and storage alternatives.” ABI Research

Cloud computing provides flexible services based on pay-as-you-go business models. The traditional cloud market is maintained by several well-known service providers, and the market share of these top providers is continuously growing. According to reports, as of October 2020, AWS, Azure, Google, and Alibaba control 63% of the entire cloud market, whereas all other providers only share 37%. Since product migration is difficult, consumers become locked in a particular provider’s ecosystems. In the future, however, we should expect a more open, fair, and trustworthy cloud resource trading market for all service providers and customers. Blockchain is inspiring the emergence of such a new cloud marketplace that encourages greater inclusivity and participation of different service parties. This decentralized market can provide more choices and opportunities for both providers and consumers in the future.  

Decentralization Requirements and Challenges

There are usually two approaches to build a cloud market: centralized and decentralized. In a centralized cloud environment, all service trading transactions and trust-related issues rely on trusted third parties (TTP), e.g., some well-known cloud service providers with good reputations. However, those providers are not always trustworthy in practice and can be biased or conspire with any parties. In a decentralized environment, however, transaction management and operations are performed by all participants, which avoids the concentration of power and makes the transactions more trustworthy. In this case, all trust guarantees come from a distributed infrastructure (e.g., blockchain), which needs to be appropriately designed, implemented, deployed, and monitored. Some considerations may include trustworthiness (e.g., blockchain platforms and consensus algorithms), security (e.g., smart contracts bugs), privacy (e.g., data confidentiality), and performance (e.g., throughput, latency).

Traditionally, SLA (Service Level Agreement) is a business concept which defines the contractual financial agreements between the roles who are engaging in the business activity. In the context of a cloud market, it is an agreement between the cloud customer and provider on the quality of the cloud service. For instance, the IaaS (Infrastructure-as-a-Service) provider, Amazon Elastic Compute Cloud (EC2), claims that the availability of its data center is no less than 99%. If this number is not achieved, it will pay back 30% credits to its customer as compensation. However, this agreement is hard to be enforced in practice. 

The blockchain technology brings in a new hint for possible solutions to address these challenges, especially the smart contract in Ethereum which makes it possible to automate the SLA on the blockchain. However, it is challenging to achieve consensus on an event that happens outside of the blockchain. The bridge between on-chain and off-chain events is called “oracle”. One of the solutions is to retrieve data from Oraclize, a third trusted company performing as a trustful data source. However, this kind of centralized solution suffers from single-point failure and is easy to compromise.

It should be also noted that each individual can violate the agreed SLA in a blockchain based decentralized cloud market. The provider may not provide the QoS (Quality of Service) they promised, and the customer may also refuse to pay for the cloud resources. In this case, a trustworthy witness mechanism is needed to judge SLA violations that occur off-chain. In traditional SLA management, this process is performed manually and is usually dominated by providers. In a decentralized cloud market, we expect to enhance SLA enforcement’s trustworthiness by introducing a new witness role. The decentralized users on the blockchain can join the SLA judgment and work as witnesses, a practice incentivised through a corresponding witness fee. However, it is still a challenge to choose effective incentive mechanisms that ensure all witnesses make trustworthy judgments.

How CONF Differs From Current Decentralized Cloud Solutions

In fact, there are already tools and projects working on decentralized cloud solutions. For example, iExec is a project that claims to create a cloud market network where everyone can monetize their applications, servers, and data-sets. Ericsson also proposed to leverage a permissioned blockchain (Hyperledger Fabric) and smart contracts to regulate transactions in the cloud market. However, the above-mentioned examples still lack trustworthy solutions to support SLA enforcement on the blockchain and lack the validation of successful industrial practices. 

ARTICONF is a recent EU project that aims to develop tools for decentralized social media applications. One of the open-source tools is CONF for planning cost-effective distributed cloud infrastructures in a trustworthy way. In CONF, A new role called “market witness” is introduced in the traditional cloud service delivering lifecycle to perform performance monitoring. The witness is designed as an anonymous participant in the blockchain system, who desires to gain revenue by reporting violations. The incentive mechanism for different witnesses in CONF is also carefully designed such that witnesses will have to always behave honestly in order to gain the maximum profit. In this way, a new blockchain-based decentralized cloud market model is proposed to tackle the challenge of detecting SLA violations in a trustworthy way. 

In summary, CONF aims to improve the existing infrastructure support in the ARTICONF tools for social network applications to optimize QoS (Quality of Service) performance metrics as well as ensure fast recovery in the presence of faults or performance drops. It is designed to build on top of the current cloud service market and meet the growing demand for trusted execution of cloud SLAs involving multiple, decentralized service providers. CONF will enhance decentralized cloud market technology promoted to a wider range of industrial market use cases.

References

• Uriarte, R.B., Zhou, H., Kritikos, K., Shi, Z., Zhao, Z. and De Nicola, R., 2020. Distributed service‐level agreement management with smart contracts and blockchain. Concurrency and Computation: Practice and Experience, p.e5800.
• Zhou, H., Ouyang, X., Su, J., de Laat, C. and Zhao, Z., 2019. Enforcing trustworthy cloud SLA with witnesses: A game theory–based model using smart contracts. Concurrency and Computation: Practice and Experience, p.e5511.
• Shi, Z., Zhou, H., Surbiryala, J., Hu, Y., de Laat, C. and Zhao, Z., 2019, December. An Automated Customization and Performance Profiling Framework for Permissioned Blockchains in a Virtualized Environment. In 2019 IEEE International Conference on Cloud Computing Technology and Science (CloudCom) (pp. 404-410). IEEE Computer Society.

This blog post was written by The University of Amsterdam team in January 2021.

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