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LDO for NextGraph guide

The @ldo/connected-nextgraph library allows you to integrate NextGraph with the LDO ecosystem. It provides a ConnectedLdoDataset that manages RDF data across decentralized NextGraph resources with real-time synchronization and read/write capabilities.

Installation

First, install the required libraries:

npm install nextgraph @ldo/connected-nextgraph

Usage:

1. Setup: Create a ConnectedLdoDataset

import { createNextGraphLdoDataset } from "@ldo/connected-nextgraph";

// Create the dataset
const ldoDataset = createNextGraphLdoDataset();

2. Connect to a NextGraph Wallet Session

Before you can create or access resources, you need an active session:

import ng from "nextgraph";

// ...

// load the wallet file
const wallet = await ng.wallet_read_file(binary_buffer);

// Open your nextgraph wallet
const mnemonic = ["word0",...]; // the 12 words of your mnemonic
const openedWallet = await ng.wallet_open_with_mnemonic_words(
  wallet,
  mnemonic,
  [pin0,pin1,pin2,pin3]
);

// Start a session
const session = await ng.session_in_memory_start(
  openedWallet.V0.wallet_id,
  openedWallet.V0.personal_site
);

ldoDataset.setContext("nextgraph", {
  sessionId: session.session_id
});

4. Create a Resource

To create a new resource in your store:

const resource = await ldoDataset.createResource("nextgraph");
if (!resource.isError) {
  console.log("Created resource:", resource.uri);
}

5. Read and Monitor a Resource**

Read Existing Resource

const resource = ldoDataset.getResource(existingUri);
const readResult = await resource.read();

if (!readResult.isError) {
  console.log("Resource loaded!", readResult.type);
}

Read Only If Unfetched

Avoid redundant fetches:

const readResult = await resource.readIfUnfetched();

Subscribe to Notifications

const unsubscribeId = await resource.subscribeToNotifications();
await resource.unsubscribeFromNotification(unsubscribeId);
await resource.unsubscribeFromAllNotifications();

6. Write Data to a Resource

You can write RDF data to a resource using update():

import { parseRdf } from "@ldo/ldo";

const ttlData = `
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
<#spiderman> a foaf:Person ; foaf:name "Spiderman" .
`;

const triples = await parseRdf(ttlData);

await resource.update({
  added: triples,
  removed: undefined
});