兄弟连区块链教程Fabric1.0源代码分析Peer DeliverClient（Deliver客户端），2018年下半年，区块链行业正逐渐褪去发展之初的浮躁、回归理性，表面上看相关人才需求与身价似乎正在回落。但事实上，正是初期泡沫的渐退，让人们更多的关注点放在了区块链真正的技术之上。

Fabric1.0源代码笔记之Peer DeliverClient（Deliver客户端）

1、DeliverClient概述

DeliverClient代码分布如下：

• peer/channel/deliverclient.go，deliverClientIntf接口定义及实现，以及DeliverClient工具函数。
• protos/orderer/ab.pb.go，AtomicBroadcast_DeliverClient接口定义和实现。

2、deliverClientIntf接口定义及实现

2.1、DeliverClient工具函数

//构造deliverClient func newDeliverClient(conn *grpc.ClientConn, client ab.AtomicBroadcast_DeliverClient, chainID string) *deliverClient //代码在peer/channel/deliverclient.go

2.2、deliverClientIntf接口定义及实现

type deliverClientIntf interface {     getSpecifiedBlock(num uint64) (*common.Block, error)     getOldestBlock() (*common.Block, error)     getNewestBlock() (*common.Block, error)     Close() error } type deliverClient struct {     conn *grpc.ClientConn     client ab.AtomicBroadcast_DeliverClient     chainID string } //构造查询Envelope func seekHelper(chainID string, position *ab.SeekPosition) *common.Envelope //r.client.Send(seekHelper(r.chainID, &ab.SeekPosition{Type: &ab.SeekPosition_Specified{Specified: &ab.SeekSpecified{Number: blockNumber}}})) func (r *deliverClient) seekSpecified(blockNumber uint64) error //r.client.Send(seekHelper(r.chainID, &ab.SeekPosition{Type: &ab.SeekPosition_Oldest{Oldest: &ab.SeekOldest{}}})) func (r *deliverClient) seekOldest() error //return r.client.Send(seekHelper(r.chainID, &ab.SeekPosition{Type: &ab.SeekPosition_Newest{Newest: &ab.SeekNewest{}}})) func (r *deliverClient) seekNewest() error //r.client.Recv()读取块 func (r *deliverClient) readBlock() (*common.Block, error) //r.seekSpecified(num)和r.readBlock() func (r *deliverClient) getSpecifiedBlock(num uint64) (*common.Block, error) //r.seekOldest()和r.readBlock() func (r *deliverClient) getOldestBlock() (*common.Block, error) //r.seekNewest()和r.readBlock() func (r *deliverClient) getNewestBlock() (*common.Block, error) //r.conn.Close() func (r *deliverClient) Close() error //cf.DeliverClient.getSpecifiedBlock(0)获取创世区块 func getGenesisBlock(cf *ChannelCmdFactory) (*common.Block, error) //代码在peer/channel/deliverclient.go

func seekHelper(chainID string, position ab.SeekPosition) common.Envelope代码如下：

func seekHelper(chainID string, position *ab.SeekPosition) *common.Envelope {     seekInfo := &ab.SeekInfo{         Start: position,         Stop: position,         Behavior: ab.SeekInfo_BLOCK_UNTIL_READY,     }     msgVersion := int32(0)     epoch := uint64(0)     env, err := utils.CreateSignedEnvelope(common.HeaderType_CONFIG_UPDATE, chainID, localmsp.NewSigner(), seekInfo, msgVersion, epoch)     return env } //代码在peer/channel/deliverclient.go