Programming Hotmoka
A tutorial on Hotmoka and smart contracts in Takamaka

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import io.takamaka.code.lang.Exported;
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@Exported
public class Person extends Storage {
    ...
}

package io.hotmoka.tutorial.examples.runs;


import static io.hotmoka.helpers.Coin.panarea;
import static io.hotmoka.node.StorageTypes.INT;
import static java.math.BigInteger.ONE;


import java.math.BigInteger;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.KeyPair;


import io.hotmoka.constants.Constants;
import io.hotmoka.crypto.api.Signer;
import io.hotmoka.helpers.GasHelpers;
import io.hotmoka.helpers.SignatureHelpers;
import io.hotmoka.node.Accounts;
import io.hotmoka.node.ConstructorSignatures;
import io.hotmoka.node.MethodSignatures;
import io.hotmoka.node.StorageTypes;
import io.hotmoka.node.StorageValues;
import io.hotmoka.node.TransactionRequests;
import io.hotmoka.node.api.Node;
import io.hotmoka.node.api.requests.SignedTransactionRequest;
import io.hotmoka.node.api.transactions.TransactionReference;
import io.hotmoka.node.api.types.ClassType;
import io.hotmoka.node.api.values.StorageReference;
import io.hotmoka.node.api.values.StorageValue;
import io.hotmoka.node.remote.RemoteNodes;


public class FamilyExported {


    private final static ClassType PERSON = StorageTypes.classNamed
        ("io.hotmoka.tutorial.examples.family.Person");


    public static void main(String[] args) throws Exception {


        // the path of the user jar to install
        var familyPath = Paths.get(System.getProperty("user.home")
        + "/.m2/repository/io/hotmoka/io-hotmoka-tutorial-examples-family/"
        + Constants.HOTMOKA_VERSION
        + "/io-hotmoka-tutorial-examples-family-" + Constants.HOTMOKA_VERSION + ".jar");


        var dir = Paths.get(args[1]);
        var payer = StorageValues.reference(args[2]);
        var password = args[3];


        try (var node = RemoteNodes.of(new URI(args[0]), 150000)) {
            // we get a reference to where io-takamaka-code-X.Y.Z.jar has been stored
            TransactionReference takamakaCode = node.getTakamakaCode();


            // we get the signing algorithm to use for requests
            var signature = node.getConfig().getSignatureForRequests();


            KeyPair keys = loadKeys(node, dir, payer, password);


            // we create a signer that signs with the private key of our account
            Signer<SignedTransactionRequest<?>> signer = signature.getSigner
            (keys.getPrivate(), SignedTransactionRequest::toByteArrayWithoutSignature);


            // we get the nonce of our account: we use the account itself as caller and
            // an arbitrary nonce (ZERO in the code) since we are running
            // a @View method of the account
            BigInteger nonce = node
            .runInstanceMethodCallTransaction(TransactionRequests.instanceViewMethodCall
            (payer, // payer
            BigInteger.valueOf(100_000), // gas limit
            takamakaCode, // class path for the execution of the transaction
            MethodSignatures.NONCE, // method
            payer)).get() // receiver of the method call
            .asBigInteger(__ -> new ClassCastException());


            // we get the chain identifier of the network
            String chainId = node.getConfig().getChainId();


            var gasHelper = GasHelpers.of(node);


            // we install the family jar in the node: our account will pay
            TransactionReference family = node
            .addJarStoreTransaction(TransactionRequests.jarStore
            (signer, // an object that signs with the payer's private key
            payer, // payer
            nonce, // payer's nonce: relevant since this is not a call to a @View method!
            chainId, // chain identifier: relevant since this is not a call to a @View method!
            BigInteger.valueOf(1_000_000), // gas limit: enough for this small jar
            gasHelper.getSafeGasPrice(), // gas price: at least the current gas price of the network
            takamakaCode, // class path for the execution of the transaction
            Files.readAllBytes(familyPath), // bytes of the jar to install
            takamakaCode)); // dependencies of the jar that is being installed


            // we increase our copy of the nonce, ready for further
            // transactions having the account as payer
            nonce = nonce.add(ONE);


            // call the constructor of Person and store in einstein the new object in blockchain
            StorageReference einstein = node.addConstructorCallTransaction
            (TransactionRequests.constructorCall
            (signer, // an object that signs with the payer's private key
            payer, // payer
            nonce, // payer's nonce: relevant since this is not a call to a @View method!
            chainId, // chain identifier: relevant since this is not a call to a @View method!
            BigInteger.valueOf(300_000), // gas limit: enough for a small object
            panarea(gasHelper.getSafeGasPrice()), // gas price, in panareas
            family, // class path for the execution of the transaction


            // constructor Person(String,int,int,int)
            ConstructorSignatures.of(PERSON, StorageTypes.STRING, INT, INT, INT),


            // actual arguments
            StorageValues.stringOf("Einstein"), StorageValues.intOf(14),
            StorageValues.intOf(4), StorageValues.intOf(1879)
            ));


            // we increase our copy of the nonce, ready for further
            // transactions having the account as payer
            nonce = nonce.add(ONE);


            StorageValue s = node.addInstanceMethodCallTransaction
            (TransactionRequests.instanceMethodCall
            (signer, // an object that signs with the payer's private key
            payer, // payer
            nonce, // payer's nonce: relevant since this is not a call to a @View method!
            chainId, // chain identifier: relevant since this is not a call to a @View method!
            BigInteger.valueOf(100_000), // gas limit: enough for a simple call
            panarea(gasHelper.getSafeGasPrice()), // gas price, in panareas
            family, // class path for the execution of the transaction


            // method to call: String Person.toString()
            MethodSignatures.ofNonVoid(PERSON, "toString", StorageTypes.STRING),


            // receiver of the method to call
            einstein
            )).get();


            // we increase our copy of the nonce, ready for further
            // transactions having the account as payer
            nonce = nonce.add(ONE);


            // print the result of the call
            System.out.println(s);
        }
    }


    private static KeyPair loadKeys(Node node, Path dir, StorageReference account, String password) throws Exception {
        return Accounts.of(account, dir)
        .keys(password, SignatureHelpers.of(node).signatureAlgorithmFor(account));
    }
}

StorageValue s = node.addInstanceMethodCallTransaction
(TransactionRequests.instanceMethodCall(
...


// method to call: String Person.toString(int)
MethodSignatures.ofNonVoid(PERSON, "toString", StorageTypes.STRING, StorageTypes.INT),


// receiver of the method to call
einstein,


// actual argument(s)
StorageValues.intOf(2019)
)).get();