Temporal Server 
本身不执行应用程序代码，而是使用 队列 计时器 和 数据库 跟踪应用程序的状态

user
    start workflow
    register application functions
    start workers
  
worker
    pull latest tasks
    hosts application functions and exxcutes them per tasks
    UserWorkflowFunctions{
        UserActivityFunction1()
        UserActivityFunction2()
    }
   return results
   
temporal-server
    timers
    TaskQueues
    database
    

temporal-server
四个服务 + 数据库

Frontend Matching History WorkerService

the History component is responsible for state transitions of individual workflows
we have Transfer Queues to be able to transactionally create tasks
a Matching component responsible for delivering tasks for queuing and matching poll for requests coming from external workers
a Front-end component because we need routing
an ElasticSearch component for indexing
a Worker component for background jobs.


Frontend gateway:   for rate limiting, routing, authorizing
History subsystem:  maintains data (mutable state, queues, and timers)
Matching subsystem: hosts Task Queues for dispatching
Worker service:     for internal background workflows





Frontend    
负责所有入站调用，包括由远程集群发起的多集群复制相关调用
grpcPort 7233   成员通讯端口6933 

History  管理工作流状态转换
7234  6934

Worker service
运行复制队列、系统工作流的后台处理
7239  6939

数据库支持 Cassandra MySQL PostgreSQL
存储任务、工作流数据、事件和可见性数据