Abmar Barros commented on ZOOKEEPER-702:

Sure Flavio, you are right.

When I said that failure detectors rely on the assumption that TCP guarantees 
massage delivery and in order, I meant that the fds are not concerned about 
these issues. I have not implemented any ordering (or loss) treatment from the 
original algorithms, which do not rely on any protocol.

Again, thanks for the feedback Benjamin. 
Doubts and suggestions are always welcome.

> GSoC 2010: Failure Detector Model
> ---------------------------------
>                 Key: ZOOKEEPER-702
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-702
>             Project: Zookeeper
>          Issue Type: Wish
>            Reporter: Henry Robinson
>            Assignee: Abmar Barros
>         Attachments: bertier-pseudo.txt, bertier-pseudo.txt, chen-pseudo.txt, 
> chen-pseudo.txt, phiaccrual-pseudo.txt, phiaccrual-pseudo.txt, 
> ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, 
> ZOOKEEPER-702.patch, ZOOKEEPER-702.patch, ZOOKEEPER-702.patch
> Failure Detector Module
> Possible Mentor
> Henry Robinson (henry at apache dot org)
> Requirements
> Java, some distributed systems knowledge, comfort implementing distributed 
> systems protocols
> Description
> ZooKeeper servers detects the failure of other servers and clients by 
> counting the number of 'ticks' for which it doesn't get a heartbeat from 
> other machines. This is the 'timeout' method of failure detection and works 
> very well; however it is possible that it is too aggressive and not easily 
> tuned for some more unusual ZooKeeper installations (such as in a wide-area 
> network, or even in a mobile ad-hoc network).
> This project would abstract the notion of failure detection to a dedicated 
> Java module, and implement several failure detectors to compare and contrast 
> their appropriateness for ZooKeeper. For example, Apache Cassandra uses a 
> phi-accrual failure detector (http://ddsg.jaist.ac.jp/pub/HDY+04.pdf) which 
> is much more tunable and has some very interesting properties. This is a 
> great project if you are interested in distributed algorithms, or want to 
> help re-factor some of ZooKeeper's internal code.

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