title: How to synchronize token(string value) between application nodes?
body: <p>We have a Spring 3 + REST application in which we are using a token to identify source of request coming in. This token is kept in-memory(in a hashmap) and used to identify the request.
  When we are multiple instance of our app(deployed on multiple tomcat instances on different machines), how can we share/sync this token between different app nodes?
  Our only requirement is to sync this token among different nodes.</p>
  
  <p>I browsed and found few apis'/software like Redis, memcached, zookeeper. I am not able to decide which one to select.</p>
  
  <p>Any kind of suggestion/comments is helpful.</p>
  
  <p>Regards,
  Pramod</p>