Play With Your Blockchain

If you haven't already, start a blockchain node in development:

ignite chain serve -r

The optional -r flag is useful in development mode since it resets the blockchain's state if it has been started before.

After the serve command has finished building the blockchain, a nameserviced binary is installed by default in the ~/go/bin directory.

The terminal window where the chain is started must remain open, so open a second terminal window to use nameserviced to run commands at the command line.

Buy a New Name

Purchase a new name using the buy-name command. The name is foo and the bid is 20token.

In the keeper for the buy name transaction, you added code to the msg_server_buy_name.go file that hard-coded the minimum bid to 10token. Any bid lower than that amount results in a rejected purchase.

nameserviced tx nameservice buy-name foo 20token --from alice

where:

• buy-name is the command that accepts two arguments
• foo is the name
• 20token is the bid
• the --from alice flag specifies the user account that signs and broadcasts the transaction

This buy-name command creates a transaction and prompts the user alice to sign and broadcast the transaction.

Here is what an unsigned transaction looks like:

{
  "body": {
    "messages": [
      {
        "@type": "/username.nameservice.nameservice.MsgBuyName",
        "creator": "cosmos1p0fprxtpk497jvczexp96sy2w43hupeph9km5d",
        "name": "foo",
        "bid": "20token"
      }
    ],
    "memo": "",
    "timeout_height": "0",
    "extension_options": [],
    "non_critical_extension_options": []
  },
  "auth_info": {
    "signer_infos": [],
    "fee": { "amount": [], "gas_limit": "200000", "payer": "", "granter": "" }
  },
  "signatures": []
}

Buy Name Transaction Details

Look at the transaction details:

• The transaction contains only one message: MsgBuyName.
• The message @type matches the package name of the corresponding proto file, proto/nameservice/tx.proto.
• The creator field is populated automatically with the address of the account broadcasting the transaction.
• The local account alice address is cosmos1p0f...km5d.
• Values of name and bid are passed as CLI arguments.

After the transaction is broadcast and included in a block, the blockchain returns a response where "code": 0 means the transaction was successfully processed.

{
  "height": "658",
  "txhash": "EDC1842BE4B596DDD9E2D34F2E372354F9BA5F6D2E4B3F1C2664F4FF05D433B7",
  "codespace": "",
  "code": 0,
  "data": "0A090A074275794E616D65",
  "raw_log": "[{\"events\":[{\"type\":\"message\",\"attributes\":[{\"key\":\"action\",\"value\":\"BuyName\"}]}]}]",
  "logs": [
    {
      "msg_index": 0,
      "log": "",
      "events": [
        {
          "type": "message",
          "attributes": [{ "key": "action", "value": "BuyName" }]
        }
      ]
    }
  ],
  "info": "",
  "gas_wanted": "200000",
  "gas_used": "47954",
  "tx": null,
  "timestamp": ""
}

Query the Chain for a List of Names

Query the chain for a list of name and corresponding values. Query commands don't need the --from flag, because they don't broadcast transactions and make only free requests.

nameserviced q nameservice list-whois

The response confirms that the name foo was successfully purchased by alice and the current price is set to 20token.

Whois:
- creator: cosmos1p0fprxtpk497jvczexp96sy2w43hupeph9km5d
  index: foo
  name: foo
  price: 20token
  value: ""
pagination:
  next_key: null
  total: "0"

Set a Value to the Name

Now that alice is an owner of the name, she can set the value to anything she wants. Use the set-name command to set the value to bar:

nameserviced tx nameservice set-name foo bar --from alice

Query for a list of names again:

nameserviced q nameservice list-whois 

The response shows that name is now foo.

Whois:
- creator: cosmos1p0fprxtpk497jvczexp96sy2w43hupeph9km5d
  index: foo
  name: foo
  price: 20token
  value: bar
pagination:
  next_key: null
  total: "0"

Buy an Existing Name

Use the bob account to purchase an existing name from alice. A successful bid requires that the buy price is higher than the current value of 20token.

nameserviced tx nameservice buy-name foo 40token --from bob

In this buy-name command, the bid is updated to the latest bid of 40token and the --from bob flag specifies that the transaction is signed by the bob address.

Query for a list of names again:

nameserviced q nameservice list-whois 

The response shows a different creator address than alice (it's now the address for bob) and the price is now 40token.

Whois:
- creator: cosmos1ku6sqpk9rgwgx98u2gs9c05aa9wrps969g0wy5
  index: foo
  name: foo
  price: 40token
  value: bar
pagination:
  next_key: null
  total: "0"

Query the Bank Balance

Use the following command to see how the alice bank balance has changed after this transaction:

nameserviced q bank balances $(nameserviced keys show alice -a)

Test an Unauthorized Transaction

Try updating the value by broadcasting a transaction from the alice account:

nameserviced tx nameservice set-name foo qoo --from alice

An error occurs because alice sold the name in a previous transaction. The results show that alice is not the owner of the name and is therefore not authorized to change the value.

{
  "height": "981",
  "txhash": "8E9951EDC5C9D76C2164BE9572B336B13CCF46653F45F54B2C1FEA702389FAE8",
  "codespace": "sdk",
  "code": 4,
  "data": "",
  "raw_log": "failed to execute message; message index: 0: Incorrect Owner: unauthorized",
  "logs": [],
  "info": "",
  "gas_wanted": "200000",
  "gas_used": "39214",
  "tx": null,
  "timestamp": ""
}

Whois:
- creator: cosmos1ku6sqpk9rgwgx98u2gs9c05aa9wrps969g0wy5
  index: foo
  name: foo
  price: 40token
  value: bar
pagination:
  next_key: null
  total: "0"

Conclusion

Congratulations 🎉. You have created the nameservice module and the nameservice application.

You successfully completed these steps:

• Learned how to work with module dependencies
• Use several scaffolding methods
• Learned about Cosmos SDK types and functions
• Used the CLI to broadcast transactions , and so much more

You are now prepared to continue your journey to learn about escrow accounts and IBC.