I would like to store data for blocks that have been placed by a player.  I could make this based on the BlockPos and then accessing a HashMap... Which ties to the question.

 

I would think that this data would be stored server side, to the world, and then whenever a player enters a new location, check with the server to see if there is any data about player placed blocks and send the player data.  Is my logic sound?

 

Also, should I store this information to disk, then load the information that is relative to the part of the world that is "active"?  Is that even possible?

 

And for the last bit, what would you recommend I store the information in?  I would only store BlockPos locations (Or is there something I should use instead) that were placed by players, so just by data existing means that the block was placed by a player.

 

Thank you!

https://mcforge.readthedocs.org/en/latest/datastorage/worldsaveddata/

Thanks!  That's exactly what I needed to get started.

 

I would like to read the data as needed.  Is there a way to determine what chunks are loaded and when readingFromNBT I can read the data that's useful?

you can keep track of each loaded chunk using ChunkEvent.Load and ChunkEvent.Unload