/example-helloworld

Hello world on Solana

Primary LanguageTypeScriptMIT LicenseMIT

Solana

Build status Gitpod Ready-to-Code

Hello world on Solana

This project demonstrates how to use the Solana Javascript API to interact with programs on the Solana blockchain.

The project comprises of:

  • An on-chain hello world program
  • A client that can send a "hello" to an account and get back the number of times "hello" has been sent

Translations

Table of Contents

Quick Start

Open in Gitpod

If you decide to open in Gitpod then refer to README-gitpod.md, otherwise continue reading.

The following dependencies are required to build and run this example, depending on your OS, they may already be installed:

If this is your first time using Rust, these Installation Notes might be helpful.

Configure CLI

  1. Set CLI config url to localhost cluster
$ solana config set --url localhost
  1. Create CLI Keypair

If this is your first time using the Solana CLI, you will need to generate a new keypair:

$ solana-keygen new

Start local Solana cluster

This example connects to a local Solana cluster by default.

Start a local Solana cluster:

$ solana-test-validator

WARNING: solana-test-validator is not currently available for native Windows. Try using WSL, or switch to Linux or macOS

Listen to transaction logs:

$ solana logs

Install npm dependencies

$ npm install

Build the on-chain program

There is both a Rust and C version of the on-chain program, whichever is built last will be the one used when running the example.

$ npm run build:program-rust
$ npm run build:program-c

Deploy the on-chain program

$ solana program deploy dist/program/helloworld.so

Run the JavaScript client

$ npm run start

Expected output

Public key values will differ:

Let's say hello to a Solana account...
Connection to cluster established: http://localhost:8899 { 'feature-set': 3714435735, 'solana-core': '1.6.6' }
Using account AiT1QgeYaK86Lf9kudqKthQPCWwpG8vFA1bAAioBoF4X containing 0.00141872 SOL to pay for fees
Using program Dro9uk45fxMcKWGb1eWALujbTssh6DW8mb4x8x3Eq5h6
Creating account 8MBmHtJvxpKdYhdw6yPpedp6X6y2U9dCpdYaZJdmwV3A to say hello to
Saying hello to 8MBmHtJvxpKdYhdw6yPpedp6X6y2U9dCpdYaZJdmwV3A
8MBmHtJvxpKdYhdw6yPpedp6X6y2U9dCpdYaZJdmwV3A has been greeted 1 times
Success

Not seeing the expected output?

  • Ensure you've started the local cluster, built the on-chain program and deployed the program to the cluster.
  • Inspect the program logs by running solana logs to see why the program failed. 
    • Transaction executed in slot 5621:
Signature: 4pya5iyvNfAZj9sVWHzByrxdKB84uA5sCxLceBwr9UyuETX2QwnKg56MgBKWSM4breVRzHmpb1EZQXFPPmJnEtsJ
Status: Error processing Instruction 0: Program failed to complete
Log Messages:
  Program G5bbS1ipWzqQhekkiCLn6u7Y1jJdnGK85ceSYLx2kKbA invoke [1]
  Program log: Hello World Rust program entrypoint
  Program G5bbS1ipWzqQhekkiCLn6u7Y1jJdnGK85ceSYLx2kKbA consumed 200000 of 200000 compute units
  Program failed to complete: exceeded maximum number of instructions allowed (200000) at instruction #334
  Program G5bbS1ipWzqQhekkiCLn6u7Y1jJdnGK85ceSYLx2kKbA failed: Program failed to complete

Customizing the Program

To customize the example, make changes to the files under /src. If you change any files under /src/program-rust or /src/program-c you will need to rebuild the on-chain program and redeploy the program.

Now when you rerun npm run start, you should see the results of your changes.

Learn about Solana

More information about how Solana works is available in the Solana documentation and all the source code is available on github

Further questions? Visit us on Discord

Learn about the client

The client in this example is written in JavaScript using:

Entrypoint

The client's entrypoint does four things

Establish a connection to the cluster

The client establishes a connection with the cluster by calling establishConnection.

Check if the helloworld on-chain program has been deployed

The client loads the keypair of the deployed program from ./dist/program/helloworld-keypair.json and uses the public key for the keypair to fetch the program account. If the program doesn't exist, the client halts with an error. If the program does exist, it will create a new account with the program assigned as its owner to store program state (number of hello's processed).

Send a "Hello" transaction to the on-chain program

The client then constructs and sends a "Hello" transaction to the program by calling sayHello. The transaction contains a single very simple instruction that primarily carries the public key of the helloworld program account to call and the "greeter" account to which the client wishes to say "Hello" to.

Query the Solana account used in the "Hello" transaction

Each time the client says "Hello" to an account, the program increments a numerical count in the "greeter" account's data. The client queries the "greeter" account's data to discover the current number of times the account has been greeted by calling reportHellos

Learn about the on-chain program

The on-chain helloworld program is a Rust program compiled to Berkley Packet Format (BPF) and stored as an Executable and Linkable Format (ELF) shared object.

The program is written using:

Programming on Solana

To learn more about Solana programming model refer to the Programming Model Overview.

To learn more about developing programs on Solana refer to the Deployed Programs Overview

Pointing to a public Solana cluster

Solana maintains three public clusters:

  • devnet - Development cluster with airdrops enabled
  • testnet - Tour De Sol test cluster without airdrops enabled
  • mainnet-beta - Main cluster

Use the Solana CLI to configure which cluster to connect to.

To point to devnet:

$ solana config set --url devnet

To point back to the local cluster:

$ solana config set --url localhost

Expand your skills with advanced examples

There is lots more to learn; The following examples demonstrate more advanced features like custom errors, advanced account handling, suggestions for data serialization, benchmarking, etc...