Q:

Want to know more about NIFI

I have a active assignment working on NIFI. 
Want to know below Question Answers? 
1.IS NIFI has any encryption mechanism in buffered queue data?  what all the security features. 
2.We can do retention on buffered data? 
3.How NIFI is having advantage working with HDFS? 
4.How long nifi can hold buffer data. What if NIFI is stopped working ,will be any data lose? 
5.How to deploy code in NIFI server. 
Please help with Answers. 

A:

Currently there is only an encrypted repository for provenance, but not for flow file repo and content repo.  There is an EncryptContent processor that can be used to encrypt the content of the flow file.  You can also create fine-grained security policies to restrict who can access each queue. 
Yes, see the documentation on back-pressure and flow file expiration https://nifi.apache.org/docs/nifi-docs/html/user-guide.html#settings
Not really sure what this question means... NiFi can be used to deliver data to HDFS, or retrieve data from it, but NiFi itself does not use HDFS. 
The amount of data that can be buffered is based on how much disk and memory you have available.  There isn't really a limitation imposed by NiFi.  All data is persisted to disk and will not be lost unless you lose the disks. 
Custom components are packaged as NARs and deployed to NiFi's lib directory and NiFi must be restarted.  https://cwiki.apache.org/confluence/display/NIFI/Maven+Projects+for+Extensions

