How can nodes interact with a Smart Contract

Question

When deploying a smart contract how can I let nodes on my own platform (mobile or web) interact with it? 

Like in the following contract:

contract Test {
    event Log(address addr);

    function logMe () public {
        Log(msg.sender);
    }
}

Do I need to have access to the private and public keys of the nodes in order to use it? Or Is it possible to allow those nodes to interact with the blockchain through their own accounts without the need to have their credentials? 

Answer 1

If you are using Remix IDE to deploy your smart contract on blockchain and you have created API for your contract, you are actually interacting with your contract with web. You can find your API and contract addresses by clicking on details in compile tab.

Then you can use web3 and inject it into your web browser ( install Metamask then you have web3 injected to the browser already )

Then create a contract API like instance by setting web3 provider and ABI and contract address you got from the above steps.

And at last, call your contract functions.

Here is the way you can interact with your deployed contract:

var fooContract = web3.eth.contract( YOUR_ABI, (err, ctr) => { return ctr} );
     web3.eth.defaultAccount = web3.eth.accounts[0];
     $scope.accounts = web3.eth.accounts;

     console.log(web3.eth.defaultAccount);
    var CONTRACT = fooContract.at('YOUR_Deployed_contract_ADDRESS',(err, ctr)=>{
      return ctr;
    } ) 

Now You can easily use the CONTRACT variable to call its public functions.

CONTRACT.contractFunction(params)