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

• Traditional Chinese
• Simplified Chinese

Table of Contents

• Hello world on Solana
  • Table of Contents
  • Quick Start
    • Configure CLI
    • Start local Solana cluster
    • Install npm dependencies
    • Build the on-chain program
    • Deploy the on-chain program
    • Run the JavaScript client
    • Expected output
      • Not seeing the expected output?
    • Customizing the Program
  • Learn about Solana
  • Learn about the client
    • Entrypoint
    • Establish a connection to the cluster
    • Check if the helloworld on-chain program has been deployed
    • Send a "Hello" transaction to the on-chain program
    • Query the Solana account used in the "Hello" transaction
  • Learn about the on-chain program
    • Programming on Solana
  • Pointing to a public Solana cluster
  • Expand your skills with advanced examples

Quick Start

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:

• Install node (v14 recommended)
• Install npm
• Install Rust v1.56.1 or later from https://rustup.rs/
• Install Solana v1.10.35 or later from https://docs.solana.com/cli/install-solana-cli-tools

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

Configure CLI

If you're on Windows, it is recommended to use WSL to run these commands

1. Set CLI config url to localhost cluster

solana config set --url http://127.0.0.1:8899

2. 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

Note: You may need to do some system tuning (and restart your computer) to get the validator to run

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://127.0.0.1:8899 { 'feature-set': 2045430982, 'solana-core': '1.7.8' }
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 TypeScript using:

• Solana web3.js SDK
• Solana web3 API

Entrypoint

The client's entrypoint does five things.

Establish a connection to the cluster

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

Establish an account to pay for transactions

The client ensures there is an account available to pay for transactions, and creates one if there is not, by calling establishPayer.

Check if the helloworld on-chain program has been deployed

In checkProgram, 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 reportGreetings.

Learn about the on-chain program

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

The program is written using:

• Solana Rust SDK

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 On-Chain 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 http://127.0.0.1:8899

Writing the client in Rust

This example details writing the client code in typescript; however the Solana client program can be written in any language. For an example client written in Rust and an accompanying write up see this repo.

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...

• Programming Examples
• Token Program
• Token Swap Program