Section4.2.1 zhiguo's notes

Summary:

1. clique.go and pbft.go are merged into one file pbft.go

2. Struct PBFT is defined, containing a ProtocolManager

3. Seal() in pbft.go is revised to work with pbft-core.go

4. util/events.go are copied from fabric/util

5. some parts related to batch in pbft-core.go and pbft.go have been commented.

11/10

19. innerBroadcast is changed to sending messages to commChan:

instance.commChan <- &types.PbftMessage{Payload: &types.PbftMessage_Commit{Commit: commit}}

replace the following code

instance.innerBroadcast(&Message{&Message_Commit{commit}})

07/10

17. two channels are used for communication:

• commChan: PBFT algorithm --> ProtocolManager. PrePrepare, Prepare, Commit messages

• ResultChan: inside PBFT algorithm, inform engine that consensus is achieved after receiving enough Commit messages.

  Note: cannot use Protocolmanager in PBFT directly because import cycle problem.

18. Message format problem

Modify the file generated by protobuf, but do not use protobuf. Use RLP of ethereum for message transmission.

01/10

14. util.go of fabric contains a hash function, which is used for hashing Request and RequestBatch.

it uses hash function sha3 from core/util/utils.go (ComputeCryptoHash).

15. RequestBatch --> Candidate Block. reqBatchStore --> blockStore

msgCert? certStore

16. ChainConfig() ---> add one more parameter as one more engine is added.

30/09

13. pset: prepared or not for a node; qset: prepared or not for a node

28/09

12. protobuf install:

https://tleyden.github.io/blog/2014/12/02/getting-started-with-go-and-protocol-buffers/

Ubuntu 14.04

If you want to use an older version (v2.5), simply do:

$ apt-get install protobuf-compiler

Otherwise if you want the latest version (v2.6):

$ apt-get install build-essential
$ wget https://protobuf.googlecode.com/svn/rc/protobuf-2.6.0.tar.gz
$ tar xvfz protobuf-2.6.0.tar.gz
$ cd protobuf-2.6.0
$ ./configure && make install

OSX

$ brew install protobuf

27/09

11. 消息类别定义Message_CONSENSUS定义在photos目录下的fabric.pb.go文件中，由proton编译而成，

其源文件为fabric.proto

10. golang protobuffer reference

A practical guide to protocol buffers (Protobuf) in Go (Golang)

http://www.minaandrawos.com/2014/05/27/practical-guide-protocol-buffers-protobuf-go-golang/#SourceCode

In fabric PBFT, messages are defined using protocolbuffer, check this reference, and also the following one:

https://stackoverflow.com/questions/40025602/how-to-use-predifined-protobuf-type-i-e-google-protobuf-timestamp-proto-wit

26/09

9. Message format revision:

1) Request in fabric_pbft contain one tx, while we use a block for negotiate consensus.

• do not use request type

• use pre_prepare type in messages.proto to hold the candidate block

8. Some unknown things:

1) watermarks, checkpoints (both clique and pbft have it) 2) Cert and CertStore do not contain any certs. 3) timer mechanisms---broadcast timer, viewchange timer, softstartTimer, startTimer etc.

7. in pbft-core.go add ProtocolManager, but vscode cannot find its definition. Method to resolve it:

~/go/bin/godef -debug -f pbft-core.go eth.ProtocolManager

find which package is not installed, then install it using gage:

go get gopkg.in/fatih/set.v0

22/09

6. timer mechanism:

timer is created by timerFactory, and it is associated with the Manager of obcBatch, so from obcBatch, one can control all timers.

5. we do not need batch, because we process candidate block with PBFT algorithm

each node sign the block with its key, just like Clique?

4. checkpoint, state related codes should be commented all

21/09

1. in ethereum, no need to execute txs or contracts

A candidate block is Finalized and then mined, then is inserted to the blockchain; InsertChain -> State_Processor.Process() -> ApplyMessage(), update state root etc.

2. in pbft, each transaction/contract is executed after consensus (need to call chaincode.ApplyTransaction)

No need to execute/rollback etc. anymore.