interact.md

title
Interacting with Your Node

Now that your node has finished compiling, let's show you how everything works out of the box.

Starting Your Node

Run the following command to start your node:

# Run a temporary node in development mode
./target/release/node-template --dev --tmp

Note the flags:

• --dev this sets up a developer node chain specification
• --tmp this saves all active data for the node (keys, blockchain database, networking info, ...) and is deleted as soon as you properly terminate your node (using ctrl+c). So every time you start with this command, you will have a clean state to work from. If the node is killed, /tmp is cleaned automatically on the restart of your computer for linux based OSs, and these files can manually be removed if needed.

With this command, you should see something like this if your node is running successfully:

2021-03-16 10:56:51  Running in --dev mode, RPC CORS has been disabled.
2021-03-16 10:56:51  Substrate Node
2021-03-16 10:56:51  ✌️  version 3.0.0-8370ddd-x86_64-linux-gnu
2021-03-16 10:56:51  ❤️  by Substrate DevHub <https://github.com/substrate-developer-hub>, 2017-2021
2021-03-16 10:56:51  📋 Chain specification: Development
2021-03-16 10:56:51  🏷 Node name: few-size-5380
2021-03-16 10:56:51  👤 Role: AUTHORITY
2021-03-16 10:56:51  💾 Database: RocksDb at /tmp/substrateP1jD7H/chains/dev/db
2021-03-16 10:56:51  ⛓  Native runtime: node-template-100 (node-template-1.tx1.au1)
2021-03-16 10:56:51  🔨 Initializing Genesis block/state (state: 0x17df…04a0, header-hash: 0xc43b…ed16)
2021-03-16 10:56:51  👴 Loading GRANDPA authority set from genesis on what appears to be first startup.
2021-03-16 10:56:51  ⏱  Loaded block-time = 6000 milliseconds from genesis on first-launch
2021-03-16 10:56:51  Using default protocol ID "sup" because none is configured in the chain specs
2021-03-16 10:56:51  🏷 Local node identity is: 12D3KooWQdU84EJCqDr4aqfhb7dxXU2fzd6i2Rn1XdNtsiM5jvEC
2021-03-16 10:56:51  📦 Highest known block at #0
2021-03-16 10:56:51  〽️ Prometheus server started at 127.0.0.1:9615
2021-03-16 10:56:51  Listening for new connections on 127.0.0.1:9944.
2021-03-16 10:56:54  🙌 Starting consensus session on top of parent 0xc43b4514877d7dcfff2459cdfe609a96cf8e9b9723589635d7215de6bf00ed16
2021-03-16 10:56:54  🎁 Prepared block for proposing at 1 [hash: 0x255bcf44df92dd4ccaca15d92d4a3db9d276e42843e21ab0cc840e207b2649d6; parent_hash: 0xc43b…ed16; extrinsics (1): [0x02bf…2cbd]]
2021-03-16 10:56:54  🔖 Pre-sealed block for proposal at 1. Hash now 0x9c14d9caccc37f8142fc348d184fb4bd8a8bc217a8979493d7f46d4220775616, previously 0x255bcf44df92dd4ccaca15d92d4a3db9d276e42843e21ab0cc840e207b2649d6.
2021-03-16 10:56:54  ✨ Imported #1 (0x9c14…5616)
2021-03-16 10:56:54  🙌 Starting consensus session on top of parent 0x9c14d9caccc37f8142fc348d184fb4bd8a8bc217a8979493d7f46d4220775616
2021-03-16 10:56:54  🎁 Prepared block for proposing at 2 [hash: 0x6cd4bd9d2a531750c10610bdaa5af0075745b6612ffa3623c14d699250b4e732; parent_hash: 0x9c14…5616; extrinsics (1): [0x3cc8…b8d9]]
2021-03-16 10:56:54  🔖 Pre-sealed block for proposal at 2. Hash now 0x05bd3317b51d717163dfa8847369d7f697c6180868c29f02d0b7ff79c5bbde3f, previously 0x6cd4bd9d2a531750c10610bdaa5af0075745b6612ffa3623c14d699250b4e732.
2021-03-16 10:56:54  ✨ Imported #2 (0x05bd…de3f)
2021-03-16 10:56:56  💤 Idle (0 peers), best: #2 (0x05bd…de3f), finalized #0 (0xc43b…ed16), ⬇ 0 ⬆ 0
2021-03-16 10:57:00  🙌 Starting consensus session on top of parent 0x05bd3317b51d717163dfa8847369d7f697c6180868c29f02d0b7ff79c5bbde3f
2021-03-16 10:57:00  🎁 Prepared block for proposing at 3 [hash: 0xa6990964cf4f184edc08acd61c3c01ac8975abbba6d42f4eec3f9658097aec04; parent_hash: 0x05bd…de3f; extrinsics (1): [0xd6ed…86a5]]
2021-03-16 10:57:00  🔖 Pre-sealed block for proposal at 3. Hash now 0xbe07e322ca525e580a3703637db191c6df091b0242a411b88fa0c43ef0ac31f8, previously 0xa6990964cf4f184edc08acd61c3c01ac8975abbba6d42f4eec3f9658097aec04.
2021-03-16 10:57:00  ✨ Imported #3 (0xbe07…31f8)
2021-03-16 10:57:01  💤 Idle (0 peers), best: #3 (0xbe07…31f8), finalized #1 (0x9c14…5616), ⬇ 0 ⬆ 0

If the number after finalized: is increasing, your blockchain is producing new blocks and reaching consensus about the state they describe!

A few notes on the example output above:

• 💾 Database: RocksDb at /tmp/substrateP1jD7H/chains/dev/db : where chain data is being written
• 🏷 Local node identity is: 12D3KooWQdU84EJCqDr4aqfhb7dxXU2fzd6i2Rn1XdNtsiM5jvEC: the node ID needed if you intend to connect to other nodes directly (more in the private network tutorial)

While not critical now, please do read all the startup logs for your node, as they help inform you of key configuration information as you continue to learn and move past these first basic tutorials.

Start the Front-End Template

To interact with your local node, we will use the Substrate Developer Hub Front-End Template, which is a collection of UI components that have been designed with common use cases in mind.

Be sure to use the correct version of the template for the version of substrate you are using as major versions are not expected to be interoperable!

You already installed the Front-End Template; let's launch it by executing the following command in the root directory of the Front-End Template:

# Make sure to run this command in the root directory of the Front-End Template
yarn start

Interact

Once the Front-End Template is running and loaded in your browser at http://localhost:8000/, take a moment to explore its components. At the top, you will find lots of helpful information about the chain to which you're connected as well as an account selector that will let you control the account you use to perform on-chain operations.

There is also a table that lists the well-known test accounts that you have access to. Some, like Alice and Bob, already have funds!

Beneath the account table there is a Transfer component that you can use to transfer funds from one account to another. Take note of the info box that describes the precision used by the Front-End Template; you should transfer at least 1000000000000 to make it easy for you to observe the changes you're making. Here we give the dave development account these funds:

Notice that the table of accounts is dynamic and that the account balances are updated as soon as the transfer is processed.

Runtime Metadata

The Front-End Template exposes many helpful features and you should explore all of them while you're connected to a local development node. One good way to get started is by clicking the "Show Metadata" button at the top of the template page and reviewing the metadata that your runtime exposes.

Pallet Interactor & Events

You can use the runtime metadata to discover a runtime's capabilities. The Front-End Template provides a helpful Pallet Interactor component that provides several mechanisms for interacting with a Substrate runtime.

Extrinsics are the runtime's callable functions; if you are already familiar with blockchain concepts, you can think of them as transactions for now. The Pallet Interactor allows you to submit unsigned or signed extrinsics and also provides a button that makes it easy to invoke an extrinsic by way of the sudo function from the Sudo pallet. You can learn more about using the "SUDO" button to invoke privileged extrinsics in the Add a Pallet tutorial.

You can select Query interactions to read the values present in your runtime's storage. The RPC and Constant options provide additional mechanisms for runtime interaction.

Like many blockchains, Substrate chains use events to report the results of asynchronous operations. If you have already used the Front-End Template to perform a balance transfer as described above, you should see an event for the transfer in the Event component next to the Pallet Interactor.

Troubleshooting

Substrate node in this tutorial is meant to be run in your local machine. If you are running it in a remote machine, you can create an ssh local port forwarding to access your node from a local Front-End Template. This allow connections to the local 9944 port be forwarded to the remote 9944 port, which Substrate listen to for web socket connections.

# Enable local port forwarding on port 9944
ssh -L 9944:127.0.0.1:9944 <remote user>@<remote host ip> -N -f

Next Steps

🎉 Congratulations!!! 🎉

You have launched a working Substrate-based blockchain, attached a user interface to that chain, and made token transfers among users. We hope you'll continue learning about Substrate!

Your next step may be:

• Extend the features of the template node in the Add a Pallet tutorial.
• Learn about forkless runtime upgrades in the Forkless Upgrade a Chain tutorial.

If you experienced any issues with this tutorial or want to provide feedback, You can ask a question on Stack Overflow and use the substrate tag or contact us on Element.