Simple Abstract Messenger Example
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An effective implementation of blockchain interoperability is sending cross-chain messages. Traditionally, without UIP, this would be a challenging task. However, UIP makes this an easy and safe process. This guide walks you through building a simple dApp that utilizes UIP to send cross-chain text messages between and other networks.
For this guide, we won't need to worry about fees as we will deploy the smart contracts on devnet, which is the commonly used Solana testnet network.
Before you begin, you'll need to enure you're familiar with the concepts and have the tools we'll be using for this guide. If you're unsure about anything, we recommend reading more via the provided links.
The programming language.
The development environment.
The toolkit.
We will be using the following native token:
Click on the token to be taken to its public faucet and complete the steps to acquire the necessary funds in your wallet.
To begin with, let's setup the working environment. We'll clone the example project.
Clone the example project from GitHub.
Change your directory to the project folder.
Install the dependencies.
To deploy your own instance of the messenger, you need to generate a custom keypair for it and put it in target/deploy:
It will generate a file called <your program address>.json, where <your program address> is the resulting public key. Move it to target/deploy:
Next, replace the program address in programs/messenger/src/lib.rs and
Anchor.toml with the public key of the generated keypair.
The Solana Messenger example employs a whitelist to only allow messages from specific contracts. For messages to be accepted, you will need to specify all the contracts from other chains that you plan on communicating with.
First, put the addresses of the deployed EVM contracts in programs/messenger/src/addresses.rs. They have to be padded with 12 zero bytes, as the EVM addresses undergo encoding to bytes.
If you want to change the chains you want to send messages to or chains you want to receive messages from, make changes to programs/messenger/src/instructions/send_message.rs or programs/messenger/src/instructions/execute.rs accordingly.
Alternatively, you can redesign the contract to add the allowed origins and destinations dynamically.
Build the Solana program by running the below command.
If you are planning to deploy to mainnet, run the following command.
After that, you are ready to deploy your program:
Now, you need to register the protocol extension. Extensions exist to let the UIP transmitters know how to interact with your program. In essence, they are WebAssembly executables that are shared by uploading to the IPFS network. Every Solana contract connected to UIP needs to register its extension to start receiving messages.
You can run the initialization script to set up the messenger config and to register the extension. For this example, you can provide the IPFS CID of the original messenger extension.
In this section, we'll take a look at sending and receiving messages.
To send a message from the Solana contract to another chain, use the send-message script.
Here, we are sending one message, choosing the destination to be Base Sepolia, paying 0.0001 SOL for fees, and setting the gas limit for execution on target chain to be 300k.
To display all the messages sent from a wallet, copy the command below, update the sender address with the EVM address and run it.
In this guide we created a dApp utilising SOL contracts to facilitate in cross-chain text messaging.