Using Beam Shaders
Why DAppnet?
Beam consists of three public networks:
- DAppnet: a testing sandbox that produces a pseudo-mining block every 15 seconds.
- Testnet: produces genuine mining blocks but is mostly a testing site before Mainnet deployment.
- Mainnet: the living Beam network with real assets.
Install DAppnet wallet
The latest version of the Beam DAppnet Wallet is on our website.
When installing DAppnet, choose the default settings to operate the local node (required) to run Beam Shader contracts. Create a new wallet (save the seed phrase).
Beam Shaders require the use of the integrated node found in the DAppnet Wallet and must remain open for this tutorial.
Withdraw from the Faucet
All DAppnet transactions (including Beam Shader deployment) contain transaction fees that are paid in Beam coins, and require a positive wallet balance.
Launch My DApp Store 
and find the Faucet Application.
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Launch Faucet >>> Get your first Beam >>> Confirm, and Beam coins will deposit into your wallet after the next mining block.
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Configuring your CLI wallet
Beam shaders are deployed via CLI wallet which can be found on our website. This tutorial uses Windows Command Prompt, but users can substitute Mac and Linux commands if desired.
Create a shader folder in your hard drive, and transfer CLI wallet archive. The shader folder should contain two files: two files: the CLI wallet archive and wallet config file.
For this tutorial, we will use our DAppnet's wallet.db(for testing purposes only. This practice is not recommended with wallets containing real assets).
Copy wallet.db from DAppnet Wallet
Beam wallets store wallet metadata (transaction history, balance, etc) locally on your hard drive in the wallet.db file.
Locate your DAppnet wallet.db in the %LOCALAPPDATA%\Beam Wallet folder. Transfer the wallet.db in the same shader folder.
Refer to our Desktop Wallet guide for wallet.db file location for macOS and Linux operating systems.
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Configure CLI wallet settings
One more crucial step before running Shader contracts involves configuring the CLI wallet settings to simplify and shorten commands.
To connect CLI wallet's to the built-in node, first edit the config file using text editor (such as Visual Studio Code) and enter the following:
log_level=debug
pass=<your wallet password>
node_addr=127.0.0.1:10005
wallet_path=wallet.db
The config file should resemble the following:
################################################################################ # General options: ################################################################################ # log level [info|debug|verbose] log_level=debug # file log level [info|debug|verbose] # file_log_level=debug # old logs cleanup period (days) # log_cleanup_days=5 ################################################################################ # Wallet options: ################################################################################ # password for the wallet pass=123 # phrase to generate secret key according to BIP-39. # seed_phrase= # address of node node_addr=127.0.0.1:10005 # path to wallet file wallet_path=wallet.db # command to execute [new_addr|send|receive|listen|init|info|export_miner_key|export_owner_key|generate_phrase] # command=listen
The testing environment is ready to deploy Shaders, all that remains is selecting the Shader contract.
Getting the Application Shader file
The simplest way to find a contract on Dappnet is to open the Dappnet Blockchain Explorer and scroll down to the list of blocks. Then click on the Contracts tab
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We will use the first one in the list, a test contract called Vault. It is very simple and we will use it in all our examples throughout the tutorial
At the time of writing list of contracts is only added on Dappnet. Also, most of the deployed contracts do not have readable description. We will add this part in the upcoming releases.
In order to run commands again this Contract Shader, we will need to download the matching Application Shader from Beam Repository. In the next parts of this tutorial we will see how to implement and build these Shaders but for now we will use a precompiled one that is committed alongside the source code here.
Download the app.wasm file and copy it to the same folder as the CLI walle executable. If you are planning to test several applications, it is convenient to create a folder for each one. So you can create a folder called vault and put the app.wasm file under it.
Running Shader commands
Open as command line interface and change directory to the location of the CLI wallet executable.
First thing we will do is print the API of the contract by running the following command:
beam-wallet-dappnet.exe shader --shader_app_file vault\app.wasm
Note that we only provide one parameter (--shader_app_file) since we assume all other parameters are set in the configuration file. We also provide a path to the application shader assuming it is located in the 'vault' folder.
The output of this command will look something like this (debug logs are on in this example)
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Let's copy the Shader output part into the text editor and format it to a standard JSON form. The end results will look like this:
{
"roles":
{
"manager":
{
"create":
{},
"destroy":
{
"cid": "ContractID"
},
"view":
{},
"view_logs":
{
"cid": "ContractID"
},
"view_accounts":
{
"cid": "ContractID"
},
"view_account":
{
"cid": "ContractID",
"pubKey": "PubKey"
}
},
"my_account":
{
"view":
{
"cid": "ContractID"
},
"get_key":
{
"cid": "ContractID"
},
"get_proof":
{
"cid": "ContractID",
"aid": "AssetID"
},
"deposit":
{
"cid": "ContractID",
"pkForeign": "PubKey",
"bCoSigner": "uint32_t",
"amount": "Amount",
"aid": "AssetID"
},
"withdraw":
{
"cid": "ContractID",
"pkForeign": "PubKey",
"bCoSigner": "uint32_t",
"amount": "Amount",
"aid": "AssetID",
"amountCoSigner": "Amount"
}
}
}
}
What you see here is the API of the Vault contract as it is presented by the Application Shader we have used. The API actions are separated into roles, in this case 'manager' and 'my_account'. Roles are only used as semantic grouping.
Let's use the 'view_accounts' method to list all accounts in the Vault
Since we are going to be working with a specific Contract Shader we will need to use the contract id that we have copied from the blockchain explorer: d9c5d1782b2d2b6f733486be480bb0d8bcf34d5fdc63bbac996ed76af541cc14
Let's run the following command:
beam-wallet-dappnet.exe shader --shader_app_file vault\app.wasm --shader_args=cid=d9c5d1782b2d2b6f733486be480bb0d8bcf34d5fdc63bbac996ed76af541cc14,role=manager,action=view_accounts
The output will show us something similar to this:
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In this case there are currently no accounts in the contract. Let's create one using a 'deposit' method. Let's start with depositing 1 BEAM. To do that we will run the following command:
beam-wallet-dappnet.exe shader --shader_app_file vault\app.wasm --shader_args="cid=d9c5d1782b2d2b6f733486be480bb0d8bcf34d5fdc63bbac996ed76af541cc14,role=my_account,action=deposit,amount=100000000"
Note that amount is set in Groth, which is 1^10-8 of BEAM.
This action will take some time to complete since the transaction is created and sent to the network. The result will be similar to this:
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The important part is the one here which explains what happened
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Let's run the 'accounts' command again and see if anything changed?
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Indeed, now we see that there is a new account identified by a public key and having a balance of 1 Beam. As an exercise you are invited tp do the same, and also get your BEAM back. You can try to get BEAM from someone elses account (hint: you can't).
In the next part of the tutorial we will see how to code this contract and deploy it on chain.