如何在应用程序节点之间同步令牌（字符串值）？

Question

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.

I browsed and found few apis'/software like Redis, memcached, zookeeper. I am not able to decide which one to select.

Any kind of suggestion/comments is helpful.

Regards, Pramod

Answer 1

I've never used zookeeper so I cannot say anything about it. Both Redis (database) and memcached (cache) will work for you. Which one is better depends on how you use tokens.

Choose Redis if:

• tokens may be stored for a long time
• no need to expire tokens
• want to handle more tokens than can be stored in memory
• want to replicate tokens to other servers so if one goes down other will provide tokens
• tokens have to survive server restart

Choose memcached if:

• tokens are valid only for certain amount of time and should expire
• amount of tokens exeed memory capacity the least recently used token will be removed
• all tokens may be stored in memory
• no need to replicate tokens to other server
• tokens don't have to survive server restart
• want to use Spring Cache abstraction