Setting up an SDK client

Once the sdk has been imported into the project, it can be used to interact with the Namada blockchain. Let's assume we have a node running on ip and port 127.0.0.1:26657 and we want to send a transaction to the network.

The SDK may be for various purposes, but in this example we will use it to send a transaction to the network.

First, we will need to implement the Client so that we can communicate with a running node.

use reqwest::{Client, Response as ClientResponse};
 
 
pub struct SdkClient {
    url: String,
    client: Client,
}
 
impl SdkClient {
    pub fn new(url: String) -> Self {
        Self {
            client: Client::new(),
            url,
        }
    }
 
    pub async fn post(&self, body: String) -> Result<ClientResponse, reqwest::Error> {
        self.client
            .post(format!("http://{}", &self.url))
            .body(body)
            .send()
            .await
    }
}

This allows us to use Client from reqwest (an external library) to send a transaction to the network.

We will need to also define some functions that the client will use to interact with the network.

#[async_trait::async_trait]
impl ClientTrait for SdkClient {
    type Error = Error;
 
    async fn request(
        &self,
        path: String,
        data: Option<Vec<u8>>,
        height: Option<BlockHeight>,
        prove: bool,
    ) -> Result<EncodedResponseQuery, Self::Error> {
        let data = data.unwrap_or_default(); // default to empty vec
        let height = height
            .map(|height| {
                tendermint::block::Height::try_from(height.0)
                    .map_err(|_err| Error::InvalidHeight(height))
            })
            .transpose()?; // convert to tendermint::block::Height
        let response = self
            .abci_query(
                Some(std::str::FromStr::from_str(&path).unwrap()),
                data,
                height,
                prove,
            )
            .await?;
 
        match response.code {
            Code::Ok => Ok(EncodedResponseQuery {
                data: response.value,
                info: response.info,
                proof: response.proof,
            }),
            Code::Err(code) => Err(Error::Query(response.info, code)),
        }
    }
 
    async fn perform<R>(&self, request: R) -> Result<R::Response, tm_rpc::Error>
    where
        R: tm_rpc::SimpleRequest,
    {
        let request_body = request.into_json();
        let response = self.post(request_body).await;
 
        match response {
            Ok(response) => {
                let response_json = response.text().await.unwrap();
                R::Response::from_string(response_json)
            }
            Err(e) => {
                let error_msg = e.to_string();
                Err(tm_rpc::Error::server(error_msg))
            }
        }
    }
}

This client will allow us to make asynchronous calls to the network and handle the responses.

Instantiating a Namada Implementation object

When constructing transactions using the sdk, we almost alwasy need a namada_impl object.

use namada_sdk::NamadaImpl; // This module allows us to access the NamadaImpl struct, which is needed for most transactions
 
let source_address = Address::from_str("tnam1v4ehgw36xq6ngs3ng5crvdpngg6yvsecx4znjdfegyurgwzzx4pyywfexuuyys69gc6rzdfnryrntx").unwrap();
let http_client = reqwest::Client::new();
let wallet = Wallet::from_mnemonic("your mnemonic here").unwrap();
let wallet: namada_sdk::wallet::Wallet<FsWalletUtils> = FsWalletUtils::new(PathBuf::from("wallet.toml"));
let shielded_ctx = FsShieldedUtils::new(Path::new("masp/").to_path_buf());
let namada_impl = NamadaImpl::new(http_client, wallet, shielded_ctx, NullIo)
        .await
        .expect("unable to construct Namada object")
        .chain_id(ChainId::from_str(CHAIN_ID).unwrap());

This object will be referenced throughout the documentation as namada_impl.

Using the SDK Setting up a wallet