Application of zookeeper in storm cluster

1. Heartbeat detection, store supervisor and worker heartbeat (including their status), so that Nimbus can monitor the status of the entire cluster, thus restarting some of the dead worker;

2. Submit a Task

3. Store all state information for the entire cluster for the UI display

4. Storm's storage structure on ZK

/-{storm-zk-root}--The root directory of storm on zookeeper (default =/storm) |   |-/assignments--Topology's task assignment Information |  
  |   |                         |-/{topology-id}-This directory holds assignments information for each topology, including: corresponding Nimbus | --The Code directory, the start time of all tasks, the mapping of each task to the machine, and the port.                         Action for |                         -(assignments) to get the values of all assignments; and (Assignment-info Storm-id) |                         --To get the Assignmentinfo information for a given Storm-id |                         --The contents stored in Assignmentinfo are: |                         --: Executor->node+port:executor->start-time-secs:node->host |                         --specifically defined in the COMMON.CLJ | --(Defrecord assignment[master-code-dir node->host executor->node+port Executor  
  ->start-time-secs]) |   |-/storms--This directory holds the ID of all running topology |  
  |   |  
  |   | |-/{topology-id}--This file holds some information about this topology, including topoLogy's name, topology start running | --the time and the state of the topology.                         Operation (active-storms), get active under current path | --topology data.                         The saved content reference class Stormbase; (Storm-base Storm-id) gets the given |      --stormbase data under Storm-id, specifically defined in COMMON.CLJ |  
  --(Defrecord stormbase [storm-name launch-time-secs status Num-workers component->executors]) |   |-/supervisors--This directory holds all the supervisor Heartbeat Information |                          
  |   |  
  |   |                         |-/{supervisor-id}-This file saves supervisor heartbeat information including: Heartbeat time, hostname, this supervisor | --Worker's port number, run time (specifically see Supervisorinfo Class).                         Operation (supervisors) Get |                         --All supervisors nodes; (Supervisor-info Supervisor-id) get a given |                              
  --Supervisor-id corresponding supervisorinfo information; specifically defined in COMMON.CLJ |       |  
  --(Defrecord supervisorinfo [time-secs hostname assignment-id used-ports meta Scheduler-meta Uptime-secs])  
  | |-/wOrkerbeats--The heartbeat of all worker |  
  |   |       |-/{topology-id}--This directory holds all the worker's heartbeat information for this topology |  
  |       |                                          
  |-/{supervisorid-port}--The heartbeat information of the worker, including the heartbeat time, worker run time, and some statistics |                                 |                                 --operation (heartbeat-storms) to get all topology with Heartbeat data |                                 --(Get-worker-heartbeat storm-id node port) Get specific one topology under |                          --the heartbeat condition of a worker (Node:port), |  
  --(Executor-beats Storm-id executor->node+port) Get a executor heartbeat status |  
  |-/errors--All generated error information | |-/{topology-id}-This directory holds the topology error message below.                      Operation (error-topologies) Get error |                      -Topology, Errors Storm-id Component-id) get |   --The error message under the given Storm-id Component-id |-/{component-id}