The STROMDAO Energy Blockchain provides a generic smart contract to cover meter point operations as business domain. This context and its smart contract is called MeterPointReading (MPR).
Retrieving a reading is as easy as running a query with the targeted meter point address.
Storing a reading is done by simply providing a reading value. However as storing a reading is done with a signed transaction, only holders of the private key might update a reading for a blockchain address.
As you see in your browser console you get an object returned, if you query the blockchain. This object provides last reading and timestamp.
Your reading will be stored on your browser id. You might refer to Instance of Business Object and how keys get generated and linked to an external ID. In this showcase we are using a special smart contract deployed at
0x0..8 - the rules of this contract allow both directions for subsequent readings.
A blockchain is a consensus system and not a database. In context of meter readings you could not easily get back all archived readings. Instead you are checking backwards (for example the last 1000 blocks) if an event occured and use the block number as indicator of which consistency was at that time.