java-algorand-sdk

AlgoSDK is a Java library for communicating and interacting with the Algorand network. It contains a REST client for accessing algod instances over the web, and also exposes functionality for generating keypairs, mnemonics, creating transactions, signing transactions, and serializing data across the network.

Prerequisites

Java 7+ and Android minSdkVersion 16+

Installation

Maven:

<dependency>
    <groupId>com.algorand</groupId>
    <artifactId>algosdk</artifactId>
    <version>1.1.4</version>
</dependency>

Quickstart

package com.algorand.algosdk.example;

import com.algorand.algosdk.algod.client.AlgodClient;
import com.algorand.algosdk.algod.client.ApiException;
import com.algorand.algosdk.algod.client.api.AlgodApi;
import com.algorand.algosdk.algod.client.auth.ApiKeyAuth;
import com.algorand.algosdk.algod.client.model.NodeStatus;


public class Main {

    public static void main(String args[]) throws Exception {
        final String ALGOD_API_ADDR = "http://localhost:8080";
        final String ALGOD_API_TOKEN = "d6f33a522f465ff12f0d263f2c3b707ac2f560bacad4d859914ada7e827902b3";

        AlgodClient client = new AlgodClient();
        client.setBasePath(ALGOD_API_ADDR);
        ApiKeyAuth api_key = (ApiKeyAuth) client.getAuthentication("api_key");
        api_key.setApiKey(ALGOD_API_TOKEN);

        AlgodApi algodApiInstance = new AlgodApi(client);
        try {
            NodeStatus status = algodApiInstance.getStatus();
            System.out.println("Algorand network status: " + status);
        } catch (ApiException e) {
            System.err.println("Exception when calling algod#getStatus");
            e.printStackTrace();
        }
    }

}

This prints:

Algorand network status: class NodeStatus {
    catchupTime: 0
    lastConsensusVersion: v4
    lastRound: 260318
    nextConsensusVersion: v4
    nextConsensusVersionRound: 260319
    nextConsensusVersionSupported: true
    timeSinceLastRound: 3620331759
}

Documentation

Javadoc can be found at (https://algorand.github.io/java-algorand-sdk/). Additional resources are located at (https://developer.algorand.org).

Cryptography

AlgoSDK depends on org.bouncycastle:bcprov-jdk15on:1.61 for Ed25519 signatures, sha512/256 digests, and deserializing X.509-encoded Ed25519 private keys. The latter is the only explicit dependency on an external crypto library - all other references are abstracted through the JCA.

Longer Example

Take a look at the example located in the examples/ directory.

Java 9+

When using cryptographic functionality, and Java9+, you may run into the following warning:

WARNING: Illegal reflective access by org.bouncycastle.jcajce.provider.drbg.DRBG

This is known behavior, caused by more restrictive language features in Java 9+, that Bouncy Castle has yet to support. This warning can be suppressed safely. We will monitor cryptographic packages for updates or alternative implementations.

Contributing to this Project

bazel build

This project uses bazel and also supports mvn. In the bazel context, it uses the maven_install bazel rule to fetch maven dependencies. More information can be found at https://blog.bazel.build/2019/03/31/rules-jvm-external-maven.html.

We should monitor the progress of features such as artifact checksumming.

To run the example project:

bazel run //examples/src/main/java/com/algorand/algosdk/example:example

To build the whole library: bazel build //:algosdk

To build individual pieces: bazel build //:algosdk_core bazel build //:algosdk_rest_api

To test: bazel test //...

To build the pom file (this auto-populates the dependencies from bazel dependencies):

bazel build //:algosdk_pom

To build specific libraries (pick and choose, e.g. for account library) bazel build //src/main/java/com/algorand/algosdk/account:account

maven support

The generated pom file provides maven compatibility and deploy capabilities.

mvn clean install
mvn clean deploy -P github
mvn clean site -P github  # for javadoc
mvn clean deploy -P release

Please update the appropriate bazel files if you use maven and contribute to the project.

Updating the algod and kmd REST clients

The algod and kmd REST clients are largely autogenerated by swagger-codegen. [https://github.com/swagger-api/swagger-codegen]

To regenerate the clients, first, check out the latest swagger-codegen from the github repo. (In particular, the Homebrew version is out of date and fails to handle raw byte arrays properly). Note OpenAPI 2.0 doesn't support unsigned types. Luckily we don't have any uint32 types in algod, so we can do a lossless type-mapping fromt uint64->int64 (Long) -> BigInteger:

curl http://localhost:8080/swagger.json | sed -e 's/uint64/int64/g' > temp.json
swagger-codegen generate -i temp.json -l java -c config.json --type-mappings Long=java.math.BigInteger

For kmd:

curl http://localhost:8080/swagger.json | sed -e 's/uint32/int64/g' > temp.json
swagger-codegen generate -i temp.json -l java -c config.json

config.json looks like:

{
  "library": "okhttp-gson",
  "java8": false,
  "hideGenerationTimestamp": true,
  "serializableModel": false,
  "supportJava6": true,
  "invokerPackage": "com.algorand.algosdk.{kmd or algod}.client",
  "apiPackage": "com.algorand.algosdk.{kmd or algod}.client.api",
  "modelPackage": "com.algorand.algosdk.{kmd or algod}.client.model"
}

For kmd, make sure you convert all uint32 types to Long types.

Finally, make sure to update all (hardcoded) BUILD.bazel files appropriately. In particular, the generated code (as of April 2019) has one circular dependency involving client.Pair. The client package depends on client.auth, but client.auth uses client.Pair which is in the client package. One more problem is that uint64 is not a valid format in OpenAPI 2.0; however, we need to send large integers to the algod API (kmd is fine). To resolve this, we do the following manual pass on generated code:

• Move Pair.java into the client.lib package (with appropriate BUILD.bazel file and renaming);
• Find-and-replace Integer with BigInteger (for uint64), Long (for uint32), etc. in com.algorand.algosdk.algod and subpackages (unnecessary for algod);
• Run an Optimize Imports operation on generated code, to minimize dependencies.

Note that msgpack-java is good at using the minimal representation.

Android Support

Significant work has been taken to ensure Android compatibility (in particular for minSdkVersion 16). Note that the default crypto provider on Android does not provide ed25519 signatures, so you will need to provide your own (e.g. BouncyCastle).