[资料整理] QoS Aggregation论文2篇

[论文1] A probabilistic approach to modeling and estimating the QoS of web-services-based workflows(IS, 2007)

San-Yih Hwang, Haojun Wang, Jian Tang, Jaideep Srivastava: A probabilistic approach to modeling and estimating the QoS of web-services-based workflows. Inf. Sci. 177(23): 5484-5503 (2007)
基于作者之前的一篇文章. Propose a probabilistic framework for QoS computation.    
        a probability-based QoS model for atomic and composite WSs that  views  a QoS  measure  as a  discrete  random  variable  with  a probability  mass  function (PMF),

讨论了三种QoS: Cost, Response time, Reliability

(S2.3) 五种basic structured constructs
(1) Sequence
(2) Parallel split/join (AND split/AND join)
(3) Exclusive choice (exclusive split/exclusive join)
(4) Discriminator (AND split/OR join)
    同步执行多个服务， 第一个返回的结果被用，之后被忽略
(5) Loop

S3.2
对上面的五种基本结构， 计算其cost/response time/reliability

[论文2] QoS Prediction for Composite Web Services with Transactions (ICSOC Workshops, 2006)

Jiangxia Wu, Fangchun Yang: QoS Prediction for Composite Web Services with Transactions. ICSOC Workshops 2006: 86-94

本文讨论了CWS中存在Transaction条件下, CWS以下QoS的计算:
Performence(Response Time), Cost, Reputation

Assumption:
(1) failure will not happen to two services simultaneously
(2) exception handling operations will not fail  

方法是比较土的, 就是把有transaction的路径加到流程图中, 这样相当于是一个新的CWS, 只要计算这个CWS的QoS即可.

注意: 本文没有估计reliability, 其中的error rate η 是指估计出来的QoS与实际的QoS的偏差.