public void writeTaskLocality(TaskName taskName, LocationId locationId) {
    String taskLocalityPath = String.format("%s/%s", keyBuilder.getTaskLocalityPath(), taskName);
    validatePaths(new String[] {taskLocalityPath});
    writeData(taskLocalityPath, locationId.getId());
  }
Fetches all the ephemeral processor nodes of a standalone job from zookeeper.
@return a list of {@link ProcessorNode}, where each ProcessorNode represents a registered stream processor.
samza-core/src/main/java/org/apache/samza/zk/ZkUtils.java