这篇文章主要介绍“Apache Pulsar二进制协议怎么实现”，在日常操作中，相信很多人在Apache Pulsar二进制协议怎么实现问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”Apache Pulsar二进制协议怎么实现”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
pulsar 使用protocolBuf 作为二进制协议编写的工具
message BaseCommand {
enum Type {
CONNECT = 2;
CONNECTED = 3;
// consumer 注册
SUBSCRIBE = 4;
// producer 注册
PRODUCER = 5;
// 向topic写入消息
SEND = 6;
// 写入的response
SEND_RECEIPT= 7;
// 写入异常的response
SEND_ERROR = 8;
// 发message 给consumer
MESSAGE = 9;
// 确认某个消息是否成功消费
ACK = 10;
// consumer 请求消息
FLOW = 11;
UNSUBSCRIBE = 12;
// 通用的一个成功的response
SUCCESS = 13;
// 通用的一个异常的response
ERROR = 14;
CLOSE_PRODUCER = 15;
CLOSE_CONSUMER = 16;
// Producer 的 response
PRODUCER_SUCCESS = 17;
// 网络层keepAlive 用的
PING = 18;
PONG = 19;
//
REDELIVER_UNACKNOWLEDGED_MESSAGES = 20;
PARTITIONED_METADATA = 21;
PARTITIONED_METADATA_RESPONSE = 22;
LOOKUP = 23;
LOOKUP_RESPONSE = 24;
CONSUMER_STATS = 25;
CONSUMER_STATS_RESPONSE = 26;
//
REACHED_END_OF_TOPIC = 27;
SEEK = 28;
GET_LAST_MESSAGE_ID = 29;
GET_LAST_MESSAGE_ID_RESPONSE = 30;
//
ACTIVE_CONSUMER_CHANGE = 31;
GET_TOPICS_OF_NAMESPACE = 32;
GET_TOPICS_OF_NAMESPACE_RESPONSE = 33;
GET_SCHEMA = 34;
GET_SCHEMA_RESPONSE = 35;
AUTH_CHALLENGE = 36;
AUTH_RESPONSE = 37;
ACK_RESPONSE = 38;
GET_OR_CREATE_SCHEMA = 39;
GET_OR_CREATE_SCHEMA_RESPONSE = 40;
// transaction related
// 事务相关的比较容易理解，下面先忽略了 50 - 61
}
// .....
}这里是客户端与server连接的channel一连上就会发送一个CONNECT 请求
这里会有一些鉴权和协议版本上报的信息。
沟通客户端版本之后，服务端就知道客户端支持哪些特性，会做一些兼容处理
相当于kafka 里面的ApiVersionRequest
// org.apache.pulsar.client.impl.ClientCnx
public void channelActive(ChannelHandlerContext ctx) throws Exception {
super.channelActive(ctx);
this.timeoutTask = this.eventLoopGroup.scheduleAtFixedRate(() -> checkRequestTimeout(), operationTimeoutMs,
operationTimeoutMs, TimeUnit.MILLISECONDS);
if (proxyToTargetBrokerAddress == null) {
if (log.isDebugEnabled()) {
log.debug("{} Connected to broker", ctx.channel());
}
} else {
log.info("{} Connected through proxy to target broker at {}", ctx.channel(), proxyToTargetBrokerAddress);
}
// Send CONNECT command
ctx.writeAndFlush(newConnectCommand())
.addListener(future -> {
if (future.isSuccess()) {
if (log.isDebugEnabled()) {
log.debug("Complete: {}", future.isSuccess());
}
state = State.SentConnectFrame;
} else {
log.warn("Error during handshake", future.cause());
ctx.close();
}
});
}这里实际上是CommandConnect 的response ，但是换了名字
（很容易对不上号）
// org.apache.pulsar.broker.service.ServerCnx
protected void handleConnect(CommandConnect connect) {
checkArgument(state == State.Start);
if (log.isDebugEnabled()) {
log.debug("Received CONNECT from {}, auth enabled: {}:"
+ " has original principal = {}, original principal = {}",
remoteAddress,
service.isAuthenticationEnabled(),
connect.hasOriginalPrincipal(),
connect.getOriginalPrincipal());
}
String clientVersion = connect.getClientVersion();
int clientProtocolVersion = connect.getProtocolVersion();
features = new FeatureFlags();
if (connect.hasFeatureFlags()) {
features.copyFrom(connect.getFeatureFlags());
}
if (!service.isAuthenticationEnabled()) {
completeConnect(clientProtocolVersion, clientVersion);
return;
}
// ......
}这个RPC是consumer用来在服务端注册的。
具体调用的位置是，在ConsumerImpl构造函数的最后一行会请求服务端和客户端进行连接，如果拿到了一个Connection，会调用这个连接成功的回调connectionOpened 如果是consumer的话就会发送这个请求，来注册consumer相关的信息。
如果和上面的CommandConnect请求联动起来，这个请求是在CommandConnect 之后发送的。
// org.apache.pulsar.client.impl.ConsumerImpl
@Override
public void connectionOpened(final ClientCnx cnx) {
// ... 上面做了一大堆的准备参数先忽略
// 构建一个subscription
ByteBuf request = Commands.newSubscribe(topic,
subscription,
consumerId,
requestId,
getSubType(),
priorityLevel,
consumerName,
isDurable,
startMessageIdData,
metadata,
readCompacted,
conf.isReplicateSubscriptionState(),
InitialPosition.valueOf(subscriptionInitialPosition.getValue()),
startMessageRollbackDuration,
schemaInfo,
createTopicIfDoesNotExist,
conf.getKeySharedPolicy());
}proto定义说明（见注释）
message CommandSubscribe {
// 这里对应subscription的4种类型
enum SubType {
Exclusive = 0;
Shared = 1;
Failover = 2;
Key_Shared = 3;
}
// topic 名字
required string topic = 1;
// subscription 名字
required string subscription = 2;
// subscription 类型
required SubType subType = 3;
// 这个是用来标记这个网络连接上的consumer标识
required uint64 consumer_id = 4;
// 网络层的请求标识
required uint64 request_id = 5;
// consumer 名字
optional string consumer_name = 6;
// consumer 的优先级，优先级高的consumer 容易先收到请求
optional int32 priority_level = 7;
// 这个subsciption是否是持久化的
// Signal wether the subscription should be backed by a
// durable cursor or not
optional bool durable = 8 [default = true];
// If specified, the subscription will position the cursor
// markd-delete position on the particular message id and
// will send messages from that point
optional MessageIdData start_message_id = 9;
// 加了一些consumer 的自定义tag Map<String,String>
/// Add optional metadata key=value to this consumer
repeated KeyValue metadata = 10;
optional bool read_compacted = 11;
optional Schema schema = 12;
// 初始化位置从哪里开始，最新还是最旧
enum InitialPosition {
Latest = 0;
Earliest = 1;
}
// Signal whether the subscription will initialize on latest
// or not -- earliest
optional InitialPosition initialPosition = 13 [default = Latest];
// geo-replication 相关，先忽略
// Mark the subscription as "replicated". Pulsar will make sure
// to periodically sync the state of replicated subscriptions
// across different clusters (when using geo-replication).
optional bool replicate_subscription_state = 14;
// If true, the subscribe operation will cause a topic to be
// created if it does not exist already (and if topic auto-creation
// is allowed by broker.
// If false, the subscribe operation will fail if the topic
// does not exist.
optional bool force_topic_creation = 15 [default = true];
// 这个是按照时间重置消费进度的时候
// If specified, the subscription will reset cursor's position back
// to specified seconds and will send messages from that point
optional uint64 start_message_rollback_duration_sec = 16 [default = 0];
// key_Share 模式使用的，暂时不看
optional KeySharedMeta keySharedMeta = 17;
}这个RPC 和 consumer相对应的，是producer在服务端注册用的，调用位置也是相同的org.apache.pulsar.client.impl.ProducerImpl.connectionOpened 里面。
/// Create a new Producer on a topic, assigning the given producer_id,
/// all messages sent with this producer_id will be persisted on the topic
message CommandProducer {
// topic
required string topic = 1;
required uint64 producer_id = 2;
// 网络层的请求编号
required uint64 request_id = 3;
/// If a producer name is specified, the name will be used,
/// otherwise the broker will generate a unique name
optional string producer_name = 4;
// 是否是加密的写入
optional bool encrypted = 5 [default = false];
// 元数据 Map<String,String>
/// Add optional metadata key=value to this producer
repeated KeyValue metadata = 6;
optional Schema schema = 7;
// 这里应该叫producer_epoch
// If producer reconnect to broker, the epoch of this producer will +1
optional uint64 epoch = 8 [default = 0];
// Indicate the name of the producer is generated or user provided
// Use default true here is in order to be forward compatible with the client
optional bool user_provided_producer_name = 9 [default = true];
// 这里是写入的3种方式
// Require that this producers will be the only producer allowed on the topic
optional ProducerAccessMode producer_access_mode = 10 [default = Shared];
// Topic epoch is used to fence off producers that reconnects after a new
// exclusive producer has already taken over. This id is assigned by the
// broker on the CommandProducerSuccess. The first time, the client will
// leave it empty and then it will always carry the same epoch number on
// the subsequent reconnections.
optional uint64 topic_epoch = 11;
}
enum ProducerAccessMode {
Shared = 0; // By default multiple producers can publish on a topic
Exclusive = 1; // Require exclusive access for producer. Fail immediately if there's already a producer connected.
WaitForExclusive = 2; // Producer creation is pending until it can acquire exclusive access
}这个是作为CommandProduce 请求的成功response
/// Response from CommandProducer
message CommandProducerSuccess {
// 网络层id
required uint64 request_id = 1;
// producer 名字
required string producer_name = 2;
// The last sequence id that was stored by this producer in the previous session
// This will only be meaningful if deduplication has been enabled.
optional int64 last_sequence_id = 3 [default = -1];
optional bytes schema_version = 4;
// The topic epoch assigned by the broker. This field will only be set if we
// were requiring exclusive access when creating the producer.
optional uint64 topic_epoch = 5;
// 这个应该和上面ProducerAccessMode 相关，后面有机会来介绍这个吧
// If producer is not "ready", the client will avoid to timeout the request
// for creating the producer. Instead it will wait indefinitely until it gets
// a subsequent `CommandProducerSuccess` with `producer_ready==true`.
optional bool producer_ready = 6 [default = true];
}这个是producer 用来发送消息到服务端用的RPC
可以通过org.apache.pulsar.client.impl.ProducerImpl.sendAsync 这个方法一路追到这个调用的位置，一般消息经过batch，加密，分块等逻辑处理之后，会将消息序列化成这个请求。
具体序列化的格式是下面这个
BaseCommand就是CommandSend
// org.apache.pulsar.common.protocol.Commands
private static ByteBufPair serializeCommandSendWithSize(BaseCommand cmd, ChecksumType checksumType,
MessageMetadata msgMetadata, ByteBuf payload) {
// / Wire format
// [TOTAL_SIZE] [CMD_SIZE][CMD] [MAGIC_NUMBER][CHECKSUM] [METADATA_SIZE][METADATA] [PAYLOAD]这里面的protocol格式实际只包含了上面的 [CMD] 部分
message CommandSend {
required uint64 producer_id = 1;
required uint64 sequence_id = 2;
optional int32 num_messages = 3 [default = 1];
optional uint64 txnid_least_bits = 4 [default = 0];
optional uint64 txnid_most_bits = 5 [default = 0];
/// Add highest sequence id to support batch message with external sequence id
optional uint64 highest_sequence_id = 6 [default = 0];
optional bool is_chunk =7 [default = false];
}这个是服务端成功处理完消息持久化之后成功的response
message CommandSendReceipt {
required uint64 producer_id = 1;
// 这个是用来保证顺序的
required uint64 sequence_id = 2;
optional MessageIdData message_id = 3;
// 这个应该是用来去重的
optional uint64 highest_sequence_id = 4 [default = 0];
}
// 这个是返回的写入成功的消息id，这个结构会在其他位置复用
message MessageIdData {
required uint64 ledgerId = 1;
required uint64 entryId = 2;
optional int32 partition = 3 [default = -1];
// 这里是
optional int32 batch_index = 4 [default = -1];
repeated int64 ack_set = 5;
optional int32 batch_size = 6;
}这个是CommandSend 异常的response
message CommandSendError {
required uint64 producer_id = 1;
required uint64 sequence_id = 2;
required ServerError error = 3;
required string message = 4;
}这个是用来告知服务端我这个consumer当前可以接受消息的数目
服务端会记录一个subscription里面每个consumer当前可以接受消息的数目
分配消息给哪个consumer的时候会按照这个数目来确定consumer当前能否接受消息。
目前了解到的位置是在connectionOpened的这个方法成功处理Subscription 注册之后会发送一个CommandFlow 请求，来让服务端推送消息。
不过可以想到，如果consumer队列是空闲的状态下都会发送这个消息。
message CommandFlow {
required uint64 consumer_id = 1;
// Max number of messages to prefetch, in addition
// of any number previously specified
required uint32 messagePermits = 2;
}这里实际上可能是服务端推消息给consumer，服务端会主动发送这个请求给consumer。（这个逻辑在服务端的 subscription 里的 dispatcher里面）
具体的调用位置在 org.apache.pulsar.broker.service.Consumer#sendMessages
这个方法在往上看一层的话都是org.apache.pulsar.broker.service.Dispatcher 这个类调用的。
这里和上面写入的格式一样这里的Command 实际上是一个RPC的header后面会加上消息的payload。
// Wire format // [TOTAL_SIZE] [CMD_SIZE][CMD] [MAGIC_NUMBER][CHECKSUM] [METADATA_SIZE][METADATA] [PAYLOAD] // // metadataAndPayload contains from magic-number to the payload included
message CommandMessage {
required uint64 consumer_id = 1;
// 这里是消息的id
required MessageIdData message_id = 2;
// 这个消息重发了多少次
optional uint32 redelivery_count = 3 [default = 0];
// 这个消息里面哪些已经被ack了
repeated int64 ack_set = 4;
}这个用来ack成功消费的消息，可以单独ack一条消息，
也可以累积确认（类似kafka）。
这里为了减少RPC的频率，在客户端做了一个batch ack 的优化。
服务端的对应处理一般会更新ManagedCursor里面保存的数据，将这个ack的结果持久化。
message CommandAck {
// ack 类型，是累积确认还是单独确认
enum AckType {
Individual = 0;
Cumulative = 1;
}
required uint64 consumer_id = 1;
required AckType ack_type = 2;
// 这里类型是repeated类型的可以把ack做batch
// In case of individual acks, the client can pass a list of message ids
repeated MessageIdData message_id = 3;
// Acks can contain a flag to indicate the consumer
// received an invalid message that got discarded
// before being passed on to the application.
enum ValidationError {
UncompressedSizeCorruption = 0;
DecompressionError = 1;
ChecksumMismatch = 2;
BatchDeSerializeError = 3;
DecryptionError = 4;
}
// 一些异常情况可能也会ack这个消息，这里会记录一些信息
optional ValidationError validation_error = 4;
repeated KeyLongValue properties = 5;
optional uint64 txnid_least_bits = 6 [default = 0];
optional uint64 txnid_most_bits = 7 [default = 0];
// 网络层请求id
optional uint64 request_id = 8;
}这个是consumer告诉服务端哪些消息需要重新被投递的RPC
message CommandRedeliverUnacknowledgedMessages {
required uint64 consumer_id = 1;
repeated MessageIdData message_ids = 2;
}这个其实是一个公用的response，如果请求没有特殊需要返回的字段的话，几乎可以被所有的请求使用。
这里不像Kafka 每个request和response 都带着一个ApiKey不会严格一一对应。
message CommandSuccess {
required uint64 request_id = 1;
optional Schema schema = 2;
}
message CommandError {
required uint64 request_id = 1;
required ServerError error = 2;
required string message = 3;
}这2个都是空的，主要作用是用来维护tcp连接应用层的keepAlive
org.apache.pulsar.common.protocol.PulsarHandler#handleKeepAliveTimeout
// Commands to probe the state of connection.
// When either client or broker doesn't receive commands for certain
// amount of time, they will send a Ping probe.
message CommandPing {
}
message CommandPong {
}到此，关于“Apache Pulsar二进制协议怎么实现”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注亿速云网站，小编会继续努力为大家带来更多实用的文章！
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