NiFi Architecture：
NiFi在主机操作系统的JVM中执行。JVM上NiFi的主要组件如下：
Web Server：
web服务器的目的是承载NiFi基于HTTP-based command and control API.
Flow Controller
The flow controller is the brains of the operation. It provides threads for extensions to run on, and manages the schedule of when extensions receive resources to execute.
流量控制器是操作的大脑。它为扩展提供了可以在其上运行的线程，并管理扩展接收要执行的资源时的调度。
Extensions
在其他文档中描述了各种类型的NiFi扩展。这里的关键是扩展在JVM中操作和执行。
FlowFile Repository：
The FlowFile Repository is where NiFi keeps track of the state of what it knows about a given FlowFile that is presently active in the flow. The implementation of the repository is pluggable. The default approach is a persistent Write-Ahead Log located on a specified disk partition.。
Content Repository：
The Content Repository is where the actual content bytes of a given FlowFile live. The implementation of the repository is pluggable. The default approach is a fairly simple mechanism, which stores blocks of data in the file system. More than one file system storage location can be specified so as to get different physical partitions engaged to reduce contention on any single volume.
Provenance Repository：
The Provenance Repository is where all provenance event data is stored. The repository construct is pluggable with the default implementation being to use one or more physical disk volumes. Within each location event data is indexed and searchable.
