The Ledger Client

5 min

To post or get data to/from the Signum Blockchain you need to create a ledger client instance. Once instantiated you have access to all the functions provided by the Node HTTP API in a comfortable and intuitive way.

It is highly recommended to use SignumJS within a decent IDE like VSCode or WebStorm to take full advantage of the auto-completion feature, making developing for Signum a breeze.

The client organizes the calls into groups according their functionality, i.e.

account
alias
asset
block
contract
message
network
transaction

Each of this subgroup provides a set of functions (see API Reference for complete documentation). For example, network related functionality like getting a list of connected peers are in network, while balance information are inside the account subgroup.

Instantiating a ledger client is very easy:

    const ledger = LedgerClientFactory.createClient({
        nodeHost: "https://europe3.testnet.signum.network"
    });

Networks

At this time of writing Signum runs two major networks: Main Net and Test Net

Test Net

As a general rule, all development should be done on Test Net first. The Signum Core Team provides a public Test Net Node: https://europe3.testnet.signum.network and a public explorer under https://t-chain.signum.network . But best is to run a local Test Net host http://localhost:6876

See how to Starting a Signum-Node for development purposes.

Main Net

The Main Net consists of hundreds of nodes, but some of them are considered as Featured Nodes, which are maintained by the Signum Core Team and further community members and guarantee better up times.

A full list of feature nodes can be found in the Main Net Explorer.

Automatic Node Selection

As a blockchain is a distributed ledger, you can connect the ledger client with any of the nodes. If you provide an application and want to offer better user experience through better loading times, it would be good if the application could be capable of selecting the "best" node. SignumJS provides such a functionality, which tests the response times of a set of given node urls. To auto-select the "best" node do the following:

const {LedgerClientFactory} = require("@signumjs/core");

async function selectBestHost() {
    try {
        const featuredNodes = [
            'http://localhost:8125', // local main net host
            'https://europe.signum.network',
            'https://europe1.signum.network',
            'https://europe2.signum.network',
            'https://europe3.signum.network',
            'https://brazil.signum.network',
            'https://australia.signum.network',
            'https://us-east.signum.network',
        ]

        const ledger = LedgerClientFactory.createClient({
            nodeHost: featuredNodes[0], // default node
            reliableNodeHosts: featuredNodes // set this list, when you plan to use the `selectBestHost` method
        })

        // by calling this method all nodes from `reliableNodeHosts` will be requested to see who's responding fastest
        // We want the ledger to be re-configured to the best node automatically, that's why we pass `true` as first argument
        const selectedHost = await ledger.service.selectBestHost(true)

        console.log('Fastest Responding Node', selectedHost)
        // you can also get the current selected host from the ledger client, like this
        // ledger.service.settings.nodeHost
    } catch (e) {
        // If the API returns an exception,
        // the return error object is of type HttpError
        handleError(e);
    }
}

(async () => {
    await selectBestHost();
})();