Querying the Chain

Now that all the code has been written, time to query the blockchain.

To test against the account operating one of the mix nodes on the testnet, use n1lcutqz94k739s39u26rvexql40ehf42zd27fwe in the following instructions:

# build the binaries
cargo build --release

# open two console windows. In one run the following
./target/release/service

# copy the printed Nym address from the console - this is used by the client when running the chain query

# in the other run
./target/release/client query-balance n1lcutqz94k739s39u26rvexql40ehf42zd27fwe <SERVICE_ADDRESS_FROM_CLIPBOARD>

The following happens:

• client and service both start their Nym clients and log the address. service is listening for incoming messages from the mixnet.
• client sends a request to service using the supplied n1... address as the Nyx account to query the balance of, and the supplied Nym address to communicate with this instance of service.
• service queries the Sandbox testnet blockchain using the broadcaster http client. It then serialises the response and returns it using SURBs to the client.

All in all, quite simple. By using the service as a proxy, the client never interacts with the blockchain, thus is not revealing metadata to the operator of the Validator nor any entities monitoring its incoming and outgoing traffic. Furthermore, the client doesn’t even need to share its Nym address with the service, as the service is able to reply via SURBs.

Creating Sandbox Account

If you wish to create an account on Sandbox to use instead of the supplied account above, the easiest way is by building the nym-cli tool and using that to create one:

# start from the root of the nym monorepo
cd tools/nym-cli
# build
cargo build --release
# create account using Sandbox testnet environment
../../target/release/nym-cli --config-env-file ../../envs/sandbox.env account create

However, since this account is fresh, it won’t have any tokens. Querying the balance will still work obviously, it will just return 0.

Get Tokens

We’re working on getting the faucet up and running again in preparation for part 2 of this tutorial: using the tokens you have privately checked the balance of to generate a bandwidth credential.

If you wish to get testnet tokens already then feel free to ask in the Dev channel on Matrix.