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These examples demonstrates several common DDC SDK use-cases for NodeJs applications. |
All examples use the account (wallet) established in the setup.md guide.
This code snippet demonstrates how to create a new public bucket on the DDC Testnet.
{% tabs %} {% tab title="TypeScript" %}
import { DdcClient, TESTNET } from '@cere-ddc-sdk/ddc-client';
const CERE = 10_000_000_000n;
/**
* The wallet should have enough CERE to pay for the transaction fees
*/
const user = 'gospel fee escape timber toilet crouch artist catalog salt icon bulb ivory';
/**
* The DDC cluster where the bucket will be created
*/
const clusterId = '0x825c4b2352850de9986d9d28568db6f0c023a1e3';
/**
* Create a DDC client instance and connect it to DDC TESTNET
*/
const client = await DdcClient.create(user, TESTNET);
/**
* Get current deposit of the DDC customer
*/
const deposit = await client.getDeposit();
console.log('Current deposit', deposit / CERE, 'CERE');
/**
* If the deposit is 0, deposit 5 CERE
*/
if (deposit === 0n) {
await client.depositBalance(5n * CERE);
console.log('Deposited 5 CERE');
}
/**
* Create a public bucket
*/
const bucketId = await client.createBucket(clusterId, {
isPublic: true,
});
console.log('Public bucket created', bucketId);
console.log('Copy the bucket ID and use it in other examples');
/**
* Disconnect the client
*/
await client.disconnect();{% endtab %} {% endtabs %}
{% hint style="info" %} A runnable version of this example is available in the examples directory. {% endhint %}
This code snippet demonstrates how to upload and download a file from a bucket on the DDC Testnet.
{% tabs %} {% tab title="TypeScript" %}
import path from 'path';
import fs from 'fs';
import { fileURLToPath } from 'url';
import { Readable } from 'stream';
import { pipeline } from 'stream/promises';
import { DdcClient, File, TESTNET } from '@cere-ddc-sdk/ddc-client';
/**
* The wallet should have enough CERE to pay for the transaction fees
*/
const user = 'gospel fee escape timber toilet crouch artist catalog salt icon bulb ivory';
/**
* The DDC bucket where the file will be stored
*/
const bucketId = 12068n;
/**
* Detect the current directory
*/
const dir = path.dirname(fileURLToPath(import.meta.url));
/**
* The file to be stored
*/
const inputFilePath = path.resolve(dir, '2mb.jpg');
/**
* The path to store the downloaded file
*/
const outputFilePath = path.resolve(dir, '2mb-downloaded.jpg');
/**
* Create a DDC client instance and connect it to DDC TESTNET
*/
const client = await DdcClient.create(user, TESTNET);
/**
* Read the file stats
*/
const inputFileStats = fs.statSync(inputFilePath);
/**
* Create the file read stream
*/
const inputFileStream = fs.createReadStream(inputFilePath);
/**
* Create a DDC file instance
*/
const ddcFile = new File(inputFileStream, {
size: inputFileStats.size,
});
/**
* Store the file into DDC
*/
const fileUri = await client.store(bucketId, ddcFile);
console.log('File stored into bucket', bucketId, 'with CID', fileUri.cid);
console.log('The file can be accessed by this URL', `https://storage.testnet.cere.network/${bucketId}/${fileUri.cid}`);
/**
* Read the file from DDC
*/
const fileResponse = await client.read(fileUri);
const outputFileStream = fs.createWriteStream(outputFilePath);
/**
* Stream the content to the destination file
*/
await pipeline(Readable.fromWeb(fileResponse.body), outputFileStream);
console.log('The file downloaded to', path.basename(outputFilePath));
/**
* Disconnect the client
*/
await client.disconnect();{% endtab %} {% endtabs %}
{% hint style="info" %} A runnable version of this example is available in the examples directory. {% endhint %}
This code snippet demonstrates how to a static Web Application (eg. website) to DDC Testnet.
{% tabs %} {% tab title="TypeScript" %}
import path from 'path';
import fs from 'fs/promises';
import { Stats, createReadStream } from 'fs';
import { fileURLToPath } from 'url';
import { DdcClient, File, Link, DagNode, TESTNET } from '@cere-ddc-sdk/ddc-client';
/**
* The wallet should have enough CERE to pay for the transaction fees
*/
const user = 'gospel fee escape timber toilet crouch artist catalog salt icon bulb ivory';
/**
* The DDC bucket where the file will be stored
*/
const bucketId = 12068n;
/**
* Detect the current directory
*/
const rootDir = path.dirname(fileURLToPath(import.meta.url));
/**
* The website directory to be uploaded
*/
const websiteDir = path.resolve(rootDir, 'website');
/**
* The website CNS name
*/
const websiteCnsName = 'website-example';
/**
* Create a DDC client instance and connect it to DDC TESTNET
*/
const client = await DdcClient.create(user, TESTNET);
/**
* Uploads a file into DDC and returns a DAG link to it
*/
async function uploadFile(filePath: string, { size }: Stats) {
const fileStream = createReadStream(filePath);
const file = new File(fileStream, { size });
const { cid } = await client.store(bucketId, file);
console.log('File:', path.relative(rootDir, filePath), 'stored into bucket', bucketId, 'with CID', cid);
return new Link(cid, size, path.relative(websiteDir, filePath));
}
/**
* Traverse the website directory and upload all files into DDC. Returns a list of DAG links to the files.
*/
async function uploadDir(dir = websiteDir) {
const links: Promise<Link>[] = [];
const files = await fs.readdir(dir);
for (const fileName of files) {
const filePath = path.join(dir, fileName);
const stats = await fs.stat(filePath);
const subLinks = stats.isDirectory() ? await uploadDir(filePath) : [uploadFile(filePath, stats)];
links.push(...subLinks);
}
return links;
}
console.log('Uploading website from', websiteDir, 'to bucket', bucketId);
const fileLinks = await Promise.all(await uploadDir(websiteDir));
/**
* Create and store a DAG node with the list of links to the website files
*/
const websiteNode = new DagNode('v1.0.0', fileLinks);
const websiteNodeUri = await client.store(bucketId, websiteNode, {
name: websiteCnsName,
});
console.log('Website uploaded into bucket', bucketId, 'with CID', websiteNodeUri.cid);
console.log(
'The website can be accessed by this URL',
`https://cdn.testnet.cere.network/${bucketId}/${websiteCnsName}`,
);
/**
* Disconnect the client
*/
await client.disconnect();{% endtab %} {% endtabs %}
{% hint style="info" %} A runnable version of this example is available in the examples directory. {% endhint %}
This code snippet demonstrates how to use a Direct Acyclic Graph (DAG) to create an events timeline stored on the DDC Testnet.
{% tabs %} {% tab title="TypeScript" %}
import { DdcClient, Link, DagNode, TESTNET, DagNodeUri } from '@cere-ddc-sdk/ddc-client';
/**
* The wallet should have enough CERE to pay for the transaction fees
*/
const user = 'gospel fee escape timber toilet crouch artist catalog salt icon bulb ivory';
/**
* The DDC bucket where the file will be stored
*/
const bucketId = 12068n;
/**
* The website CNS name
*/
const streamCnsName = 'events-stream-example';
/**
* Create a DDC client instance and connect it to DDC TESTNET
*/
const client = await DdcClient.create(user, { ...TESTNET, logLevel: 'silent' });
/**
* Get the previous event root attached to the stream CNS record
*/
const prevEvent = await client.read(new DagNodeUri(bucketId, streamCnsName)).catch(() => null);
/*
* Create a new root event with a link to the previous event root (if exists)
*/
const rootEvent = new DagNode(
JSON.stringify({
type: 'example-run',
time: new Date().toISOString(),
}),
prevEvent ? [new Link(prevEvent.cid, prevEvent.size)] : [],
);
/**
* Store the new root event to the DDC and update the stream CNS record
*/
const rootEventUri = await client.store(bucketId, rootEvent, {
name: streamCnsName,
});
console.log('Event stream stored into bucket', bucketId, 'with CID', rootEventUri.cid);
/**
* Recursevly read the last 5 events from the DDC starting from the root event (the latest one)
*/
async function readEventNodes(rootNodeUri: DagNodeUri, depth = 5): Promise<DagNode[]> {
const rootNode = await client.read(rootNodeUri);
const [prevNodeLink] = rootNode.links;
if (!prevNodeLink || depth === 1) {
return [rootNode];
}
const prevNodeUri = new DagNodeUri(bucketId, prevNodeLink.cid);
const prevNodes = await readEventNodes(prevNodeUri, depth - 1);
return [rootNode, ...prevNodes];
}
const allNodes = await readEventNodes(rootEventUri);
console.log(
'All events in the stream:',
allNodes.map((event) => JSON.parse(event.data.toString())),
);
/**
* Disconnect the client
*/
await client.disconnect();{% endtab %} {% endtabs %}
{% hint style="info" %} A runnable version of this example is available in the examples directory. {% endhint %}