NATS文档
  • 欢迎
  • 发行备注
    • 最新情况
      • NATS 2.2
      • NATS 2.0
  • NATS 概念
    • 概览
      • 比较 NATS
    • 什么是NATS
      • 演练安装
    • 基于主题的消息
    • 核心NATS
      • 发布和订阅
        • 发布/订阅演 练
      • 请求和响应
        • 请求/响应 演练
      • 队列组
        • 队列 演练
    • JetStream
      • 流
      • 消费者
        • 示例
      • JetStream 演练
      • 键值对存储
        • 键值对存储演练
      • 对象存储
        • 对象存储演练
    • 主题映射与分区
    • NATS服务器基础架构
      • NATS部署架构适配
    • 安全
    • 连接性
  • 使用 NATS
    • NATS工具
      • nats
        • nats基准测试
      • nk
      • nsc
        • 基础
        • 流
        • 服务
        • 签名密钥
        • 撤销
        • 管理操作
      • nats-top
        • 教程
    • 用NATS开发
      • 一个NATS应用的解剖
      • 连接
        • 连接到默认服务器
        • 连接到特定服务器
        • 连接到群集
        • 连接名称
        • 用用户名和密码做认证
        • 用令牌做认证
        • 用NKey做认证
        • 用一个可信文件做认证
        • 用TLS加密连接
        • 设置连接超时
        • 乒乓协议
        • 关闭响应消息
        • 杂技功能
        • 自动恢复
          • 禁用自动重连
          • 设置自动重新连接的最大次数
          • 随机
          • 重连尝试之间暂停
          • 关注重连事件
          • 重连尝试期间缓存消息
        • 监视连接
          • 关注连接事件
          • 低速消费者
      • 接收消息
        • 同步订阅
        • 异步订阅
        • 取消订阅
        • N个消息后取消订阅
        • 回复一个消息
        • 通配符订阅
        • 队列订阅
        • 断开连接前清除消息
        • 接收结构化数据
      • 发送消息
        • 包含一个回复主题
        • 请求回复语义
        • 缓存刷入和乒
        • 发送结构化数据
      • JetStream
        • 深入JetStream模型
        • 管理流和消费者
        • 消费者详情
        • 发布到流
        • 使用键值对存储
        • 使用对象存储
      • 教程
        • 用go做个自定义拨号器
  • 运行一个NATS服务
    • 安装、运行和部署NATS服务
      • 安装一个NATS服务
      • 运行和部署一个NATS服务
      • Windows服务
      • 信号
    • 环境约束
    • NATS和Docker
      • 教程
      • Docker Swarm
      • Python 和 NGS 运行在Docker
      • JetStream
    • NATS和Kubernetes
      • 用Helm 部署NATS
      • 创建一个Kubernetes群集
      • NATS群集和认证管理
      • 用cfssl保护NATS群集
      • 用负载均衡来保护外部的NATS访问
      • 在Digital Ocean用Helm创建超级NATS群集
      • 使用Helm从0到K8S再到叶子节点
    • NATS服务的客户端
    • 配置 NATS服务
      • 配置 JetStream
        • 配置管理 Management
          • NATS管理命令行
          • 地形
          • GitHub Actions
          • Kubernetes控制器
      • 群集
        • 群集配置
        • JetStream 群集
          • 管理
      • 网关超级群集
        • 配置
      • 叶子节点
        • 配置
        • JetStream在叶子节点
      • 安全加固NATS
        • 使用 TLS
        • 认证
          • 令牌
          • 用户名/密码
          • TLS认证
            • 群集中的TLS认证
          • NKeys
          • 认证超时
          • 去中心化的 JWT 认证/授权
            • 使用解析器查找帐户
            • 内存解析器教程
            • 混合认证/授权安装
        • 授权
        • 基于账户的多租户
        • OCSP Stapling
      • 日志
      • 使用监控
      • MQTT
        • 配置
      • 配置主题映射
      • 系统事件
        • 系统时间和去中心化的JWT教程
      • WebSocket
        • 配置
    • 管理和监控你的NATS服务基础架构
      • 监控
        • 监控 JetStream
      • 管理 JetStream
        • 账号信息
        • 命名流,消费者和账号
        • 流
        • 消费者
        • 数据复制
        • 灾难回复
        • 加密Rest
      • 管理JWT安全
        • 深入JWT指南
      • 升级一个群集
      • 慢消费者
      • 信号
      • 跛脚鸭模式
  • 参考
    • 常见问题
    • NATS协议
      • 协议演示
      • 客户端协议
        • 开发一个客户端
      • NATS群集协议
      • JetStream API参考
  • 遗产
    • STAN='NATS流'
      • STAN概念
        • 和NATS的关系
        • 客户端连接
        • 频道
          • 消息日志
          • 订阅
            • 通常的
            • 持久化的
            • 队列组
            • 重新投递
        • 存储接口
        • 存储加密
        • 群集
          • Supported Stores
          • Configuration
          • Auto Configuration
          • Containers
        • Fault Tolerance
          • Active Server
          • Standby Servers
          • Shared State
          • Failover
        • Partitioning
        • Monitoring
          • Endpoints
      • Developing With STAN
        • Connecting to NATS Streaming Server
        • Publishing to a Channel
        • Receiving Messages from a Channel
        • Durable Subscriptions
        • Queue Subscriptions
        • Acknowledgements
        • The Streaming Protocol
      • STAN NATS Streaming Server
        • Installing
        • Running
        • Configuring
          • Command Line Arguments
          • Configuration File
          • Store Limits
          • Persistence
            • File Store
            • SQL Store
          • Securing
        • Process Signaling
        • Windows Service
        • Embedding NATS Streaming Server
        • Docker Swarm
        • Kubernetes
          • NATS Streaming with Fault Tolerance.
    • nats账号服务
      • Basics
      • Inspecting JWTs
      • Directory Store
      • Update Notifications
由 GitBook 提供支持
在本页
  • NATS Client Development Guide
  • Client connection options
  • Client authorization
  • Verbose mode
  • Pedantic mode
  • Ping/pong interval
  • Parsing the protocol
  • Deciding on a parsing strategy
  • Storing and dispatching subscription callbacks
  • Implementing request/response
  • Error handling, disconnecting and reconnecting
  • Cluster support
  1. 参考
  2. NATS协议
  3. 客户端协议

开发一个客户端

上一页客户端协议下一页NATS群集协议

最后更新于2年前

NATS Client Development Guide

This guide provides you with considerations for developing NATS clients, including:

  • CONNECT handling

  • Authorization

  • Verbose (acks)

  • Pedantic mode

  • Ping/pong interval

  • Parsing the protocol

  • Deciding on a parsing strategy

  • Storing and dispatching subscription callbacks

  • Implementing requests/response

  • Error handling, disconnecting and reconnecting

  • Cluster support

Probably the best way to learn about implementing a client is to look at one of the client's maintained by the Synadia team. These clients are generally full featured, so if you can use them, that is even better, but if you have to write a client these may go beyond your needs while still capturing many of the design considerations discussed here.

Client connection options

Client authorization

By default clients can connect to the server in unauthenticated mode. You can configure the NATS server to require password authentication to connect.

For example, using the command line:

nats-server -DV -m 8222 -user foo -pass bar

The client must then authenticate to connect to the server. For example:

nats.Connect("nats://foo:bar@localhost:4222")

Verbose mode

When 'verbose' is enabled (via the CONNECT message), the NATS server will return +OK to acknowledge receipt of a valid protocol message. The NATS server automatically runs in verbose mode. Most client implementations disable verbose mode (set it to false in the CONNECT message) for performance reasons.

Pedantic mode

A client may also support 'pedantic' mode. Pedantic mode indicates to the server that strict protocol enforcement is required.

Ping/pong interval

NATS implements auto-pruning. When a client connects to the server, the server expects that client to be active. Periodically, the NATS server pings each subscriber, expecting a reply. If there is no reply within the configurable time limit, the server disconnects the client.

Parsing the protocol

The NATS message structure includes the Subject string, an optional Reply string, and an optional Data field that is a byte array. The type Msg is a structure used by Subscribers and PublishMsg().

type Msg struct {
    Subject string
    Reply   string
    Data    []byte
    Sub     *Subscription
}

A NATS publisher publishes the data argument to the given subject. The data argument is left untouched and needs to be correctly interpreted on the receiver. How the client parses a NATS message depends on the programming language.

Deciding on a parsing strategy

Generally, protocol parsing for a NATS client is a string operation. In Python, for example, string operations are faster than regex. The Go and Java clients also use string operations to parse the message. But, if you look at the Ruby client, regex is used to parse the protocol because in Ruby regex is faster that string operations.

In sum, there is no magic formula for parsing—it depends on the programming language. But, you need to take into consideration how you are going to parse the message when you write a client.

Storing and dispatching subscription callbacks

When you make a subscription to the server, you need to store and dispatch callback handlers.

On the client side, you need a hash map for this data structure. The hash map will be storing the callback that maps the subscription ID to the subscription.

The key of the hash map is the subscription ID. The key is used to look up the callback in the hash map. When you process the NATS message off the wire, you pass the parameters subject, reply subject, and the payload to the callback handler, which does its work.

Thus, you must store the mapping of subscription ID to the callback. Inside the subscription you have the callback.

Implementing request/response

When to use pub/sub vs. req/rep depends on your use case. Run the tutorials for each to understand the differences between each style of implementation.

Error handling, disconnecting and reconnecting

Considerations for error handling primarily include handling client disconnections and implementing retry logic.

Cluster support

The NATS client has reconnection logic. So, if you are implementing clustering, you need to implement reconnect callbacks a priori, meaning you cannot modify it during runtime. When you start it, you need to have that information already.

Clients can connect in authenticated or unauthenticated mode, as well as verbose mode which enables acknowledgements. See the for details.

NATS provides a text-based message format. The text-based makes it easy to implement NATS clients. The key consideration is deciding on a parsing strategy.

The NATS server implements a that is fast and efficient. Off the wire, a NATS message is simply a slice of bytes. Across the wire the message is transported as an immutable string over a TCP connection. It is up to the client to implement logic to parse the message.

go
node
typescript
python2
python asyncio
java
c#
ruby
c
protocol
zero allocation byte parser
protocol documentation