区块链共识窗口下Web服务兼容性评价方法

doi:10.19665/j.issn1001-2400.2020.05.009

摘要/Abstract

摘要：

针对传统的服务计算框架下,web服务的性能评价缺乏时效性且缺乏服务兼容性能评价方法的问题,提出了一种基于马尔科夫链和共识时间窗口的兼容性能评价方法。首先,提出增强型面向服务架构计算框架,利用区块链共识算法产生时间较为固定的特点,将时间分隔成长度固定的时间窗口,从而产生服务性能的“时效性”。其次,提出服务兼容性能评价方法,利用当前时段服务池调用记录,计算出能够预测服务下一时段服务兼容性的参数“连接值”。最后,选取4种共识算法 BitCoin PoW、 PPCoin DPoS、Fabric PBFT以及PBFT+DPoS,对这4种共识算法产生的时间窗口下服务池的离散程度、连接值的分布、兼容性能评价效果进行了对比。结果表明,笔者提出的计算模型,可以准确地区分服务池内服务的兼容属性,区分度随区块链共识算法改变,效果排名依次是PoW,PBFT,DPoS,PBFT+DPoS。

关键词: 区块链, 共识算法, 服务组合, 兼容性能, 马尔科夫过程

Abstract:

In the traditional Service Oriented Architecture(SOA),evaluations of services are results from accumulated remarks, which means that they lack real-time feedbacks. In this paper, we propose an advanced architecture combined by SOA and block-chain. We take the advantage of the stable time-slot generated by the consensus algorithm to clock the service pool, making it possible to evaluate the real-time states of services. Moreover, we propose a mathematical model based on the Markov Chain to assess and predict the compatibility of a service in a time-slot. And we assess and evaluate the distribution of compatibility by bringing in four well-known consensus algorithms (Bitcoin’s PoW, PPCoin’s DPoS, Fabric PBFT, PBFT+DPoS) which generate different lengths of time-slots. The result shows that our compatibility assessment model works well and that the distribution varies with different consensus algorithms with the rankings of effects as follows: PoW,PBFT,DPoS, and PBFT+DPoS.

Key words: blockchain, consensus algorithm, service composition, compatibility, Markovian Process

中图分类号:

TP393

马诗洋,董学文,权义宁,佟威,杨凌霄. 区块链共识窗口下Web服务兼容性评价方法[J]. 西安电子科技大学学报, 2020, 47(5): 63-69.

MA Shiyang,DONG Xuewen,QUAN Yining,TONG Wei,YANG Lingxiao. Method for evaluation of web services compatibility based on the blockchain’s consensus algorithm[J]. Journal of Xidian University, 2020, 47(5): 63-69.

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SOA	ASOA
中心化存储,数据存储安全性低	分布式存储,保护数据安全,方便数据维护
存在恶意篡改可能性	区块链系统密码学特性保障数据不可篡改
服务状态缺乏时效性	共识算法产生稳定时间窗口,赋予服务“时效性”

共识算法	共识时间/s	服务池离散程度γ
BitCoin PoW	600.0	0.95
Fabric PBFT	10.0	0.70
点点币的DPoS	3.0	0.50
PBFT + DPoS	0.5	0.35

共识算法	分布区间	区间间隔(极差)	方差	离散度	区分度
PoW	[0.007 5,0.012 7]	0.005 2	1.023 16E-06	高	高
PBFT	[0.008 3,0.011 6]	0.003 3	6.343 1E-07	较高	较高
DPoS	[0.008 6,0.011 1]	0.002 5	2.969 97E-07	中等	中等
PBFT+DPoS	[0.009 1,0.010 9]	0.001 8	1.424 51E-07	较低	较低