Question: How to store the temporary data in Apache storm?

In storm topology, bolt needs to access the previously processed data.

```
Eg: if the bolt processes varaiable1 with result as 20 at 10:00 AM.

```

and again `varaiable1` is received as `50` at `10:15 AM` then the result should be `30 (50-20)` 

later if varaiable1 receives `70` then the result should be `20 (70-50)` at `10:30`.

How to achieve this functionality.

Answer: 
In short, you wanted to do micro-batching calculations with in storm’s running tuples.
First you need to define/find key in tuple set. 
Do field grouping(don't use shuffle grouping) between bolts using that key. This will guarantee related tuples will always send to same task of downstream bolt for same key.
Define class level collection List/Map to maintain old values and add new value in same for calculation, don’t worry they are thread safe between different executors instance of same bolt.
I'm afraid there is no such built-in functionality as of today.
But you can use any kind of distributed cache, like memcached or Redis. Those caching solutions are really easy to use.