From 77d7d734fedf2a3b4469b5e9888d36f82fae42e3 Mon Sep 17 00:00:00 2001 From: amaury Date: Wed, 12 Apr 2023 14:13:39 +0200 Subject: [PATCH] done --- recherches/Raynal18.md | 37 ++++++++++++++++++++++++++++++++++++- 1 file changed, 36 insertions(+), 1 deletion(-) diff --git a/recherches/Raynal18.md b/recherches/Raynal18.md index b104c2a..6c42515 100644 --- a/recherches/Raynal18.md +++ b/recherches/Raynal18.md @@ -1,6 +1,11 @@ # Michel Raynal - FAULT-TOLERANT DISTRIBUTED SERVICES IN MESSAGE-PASSING SYSTEMS +## Connexes + +Comprendre la théorie derrière le Failure Detector. __T. D. Chandra and S. Toueg, “Unreliable failure detectors for reliable distributed systems,” J. ACM, vol. 43, no. 2, pp. 225–267, 1996.__ + ## Definition + Fault-Tolerence: The service remains uninterrupted even if some component in the network fail. Distributed System: A collection of computers (or nodes) that communicate amongst themselves [...] to perform a given task. Distributed Computing: The use of a Distributed System to solve a computational problems. @@ -8,6 +13,8 @@ Static system: The system composition is fixed. Dynamic system: nodes may enter, leave or move in the system with time. FLP impossibility result: It is impossible to design a distributed system that is both asynchronous and fault-tolerant. +ADD (Average Delayed/Dropped): model used to describe realisticly the network. + Data-Strcutures: - linearizability: a data structure is said to be linearizable if it guarantees that all operations appear to happen at a single pointin time between the invocation and response of the operation. @@ -28,6 +35,12 @@ Usefull terms: - synchronous/asynchronous systems - static/dynamic systems + +algorithms of sharded registers: +- RAMBO +- DynaStore +- Baldoni et Al. + ## Chapter 1 He's began to define the terms of distributed systemsn and the possibles uses cases. @@ -41,4 +54,26 @@ Actually the Failure Detectors needs a certain level of synchronicity to work. A ### Fault-Tolerant Register He defined a "shared register" and explained how it's complicated to implementing them due to the possibility of faulty nodes. And he present the solution who's the Fault-Tolerant Register. He also present the "linearizability" property and how it's used to define the Fault-Tolerant Register. -Finally he introduce two implementation of the Fault-Tolerant Register: one who's crash-tolerent and the other one who's Byzantine-tolerent. \ No newline at end of file +Finally he introduce two implementation of the Fault-Tolerant Register: one who's crash-tolerent and the other one who's Byzantine-tolerent. + +## Chapter 2 + +He precised the context of the implementation. We are on an arbitrary, partitionnable network composed of Average Delayed/Dropped channels (ADD). +The failure detectors can be defined by their accuracy and completness tel que: + +- Strong completeness is satisfied if the failure detector of each node eventually suspects all nodes that are crashed. +- Eventual strong accuracy is satisfied if the failure detector of every node eventually stops suspecting all nodes that are correct. + +He described he's algorithm. + +## Chapter 3.1 + +He purposed a new Fault-Tolerant Register who's crash-tolerent and churn proof. +The algorithm is tolerent of node who could crash or leave the system. +There is no hierarchy between the nodes. And the algorithm emulated a shared memory using the message-passing model. + +## Chapter 3.2 + +He purposed a new Fault-Tolerant Register who's crash-tolerent and churn and Byzantin proof. +The model add a notion of server in the previous model (where we had only clients). And a system of asymetric signature. +Also he proved than it's impossible with thiss model to determine the number of Byzantin server as a fraction of the total number of servers.