Hello, I have a custom NiFi controller service that retrieves data from an external web service via HTTP requests. The results from these HTTP requests will be needed at various points throughout my process flow. In some situations, I could end up needing to access the HTTP response dozens or even hundreds of times.
Given that the results of the HTTP request rarely change, I’d like them to be cached by my service and returned to my processors when needed. I’d need some way to explicitly clear the cache for those occasions when the data in the service does change. I’ve looked at using the DistributedMapCacheClientService implementation to cache my web service’s results, but it seems like that connects to a server via a socket connection and that doesn’t seem like it would be all that much more efficient than calling the web service directly. I’ve also looked at using the service’s state manager to store the results as state, but my data is a little more complex than what the documentation for state suggests is optimal: I don’t think my total map size will get to 1MB in size but it could be possible. Am I overthinking this? Would a simpler solution like creating a simple Java HashMap inside my controller service be adequate? I could empty the contents of the hash map whenever the controller services is enabled/disabled. Would the memory used by this kind of simplified local caching cause problems somewhere down the line? Are there other caching strategies I should be considering? Thanks -Tim
