File size: 2,120 Bytes
f4a7cbe |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 |
<!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
//-->
# ZooKeeper's System Specification of TLA+
## Overview
ZooKeeper's system specification of TLA+ focuses on the implementation of the Zookeeper Atomic Broadcast(ZAB) consensus protocol (or, [ZAB1.0](https://cwiki.apache.org/confluence/display/ZOOKEEPER/Zab1.0)).
As is shown by the informal description of [ZAB1.0](https://cwiki.apache.org/confluence/display/ZOOKEEPER/Zab1.0), the implementation of ZAB that used in ZooKeeper production differs a lot from its original design.
We make this system specification to grasp the core logic of the ZAB's implementation especially.
The [sysetm specification](zk-3.7/ZkV3_7_0.tla) written in TLA+ is precise without ambiguity, and testable with existed tools like the TLC model checker. (We have done a certain scale of model checking to verify its correctness!)
The system specification can serve as the super-doc supplementing detailed system documentation for the ZooKeeper developers. It can evolve incrementally without high cost as the system develops over time, continually ensuring correctness for both the design and the implementation.
We have also made a formal [specification](zk-3.7/FastLeaderElection.tla) for Fast Leader Election in Zab since ZAB 1.0 depends on FLE to complete the election phase.
If you have any question or find any problem of the specification, please contact us.
|