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I have a rpi3 and it have to be a node of a blockchain. I have a script python on raspberry, which gather data from an accelerometer. Checked some conditions,I should store these data,plus other strings(Gps coordinates and date)in a blockchain. I am using testrpc and I've installed web3.js.

I start my tester from cmd inserting "testrpc" and it shows me the available accounts with theirs private keys. Then to interact with it I have to open another cmd window,right?

To interact with a generic node I have to use web3 library,so from the second cmd window I should run a node.js script,which takes data from python script( with a socket for example) and use web3 function to interface with node. Something like this:

var Web3 = require('web3');
var web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));

web3.isConnected();

Now,imaging I wanted to store on blockchain just some values written in node.js(and not the real data yet). I don't know. For example var x=5 e var y=10. What would be the complete code to do this?

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store on blockchain

Ethereum is a bit more complicated than a generic data storage cloud. You have to make yourself familiar with the concept of smart contracts, such as how you deploy them and how you interact with them. The go-to tool right now is Truffle . If I may ask, what do you intend to make the nodejs talk to, on your raspberry pi ?

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  • For what i've understood,in this case node.js works as a simply wrapper which allow python script to comunicate with an ethereum node,through web3 api.So I "pass" data from one script to another and finally,Always in the second script,i will write some code to connect to node and deploy a contract who storage my data in the blockchain. My problem is the part of "connection to node " code...please help me,i am lost...xD – Nick9214 Jun 5 '17 at 14:05
  • When connecting nodejs to nodes, two components come into play. Your NodeJS part should do it, now you need to have a node client running. For development, it's recommended to use TestRPC, as it has no mining time, enough ether to test, and you can define the numbner of accounts by adding --accounts="123" when launching it. For a real node, use geth, and look up the right RPC flags. I recommend --rpc --rpcport 8545 --rpcaddr 0.0.0.0 --rpccorsdomain "*" --rpcapi "eth,web3,personal,debug" , but please change them for production accordingly. – Nikita Fuchs Jun 7 '17 at 12:05
  • Sorry I don't understand " When connecting nodejs to nodes,two components come into play".My problem is that I don't know what to write in node.js script to connect with a node,beside those 3 lines I wrote up here.Or,to be more clear,I don't know how to write the code between those 3 lines and the body of smart contract – Nick9214 Jun 7 '17 at 21:15

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