title: Flume use of multiplexing channel selector
body: <p>I am trying to implement flume to ingest the data around 1TB. For this I am trying to use the multiplexing channel selector.</p>
  
  <p>There are some examples available that shows how to use the multiplexing channel selector.</p>
  
  <p><b>My question is how one can determine the header content of an event?  </b></p>
  
  <p>For example, in below configuration, I am using multiplexing channel selector with header as State and mapping is made to CN, ID, IN etc.</p>
  
  <pre><code>spoolDirAgent.sources.source1.selector.type = multiplexing
  spoolDirAgent.sources.source1.selector.header = State
  spoolDirAgent.sources.source1.selector.mapping.CN = channel1
  spoolDirAgent.sources.source1.selector.mapping.IN = channel2
  spoolDirAgent.sources.source1.selector.mapping.ID = channel2
  spoolDirAgent.sources.source1.selector.defalut = channel1
  </code></pre>
  
  <p>Also if possible, please let me know how to use the event headers in flume sources?</p>
  
  <p>Thanks in advance!</p>