Note: This repo is deprecated in favor of nkn-sdk-js.

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JavaScript implementation of NKN client.

Send and receive data between any NKN clients without setting up a server.

Note: This is a client version of the NKN protocol, which can send and receive data but not relay data (mining). For node implementation which can mine NKN token by relaying data, please refer to nkn.

For npm:

npm install nkn-client

And then in your code:

const nkn = require('nkn-client');

For browser, use dist/nkn.js or dist/nkn.min.js.

Create a client with a generated key pair:

const client = nkn();

Or with an identifier (used to distinguish different clients sharing the same key pair):

const client = nkn({
  identifier: 'any string',
});

Get client key pair:

console.log(client.key.seed, client.key.privateKey, client.key.publicKey);

Create a client using an existing secret seed:

const client = nkn({
  identifier: 'any string',
  seed: '2bc5501d131696429264eb7286c44a29dd44dd66834d9471bd8b0eb875a1edb0',
});

Secret seed should be kept SECRET! Never put it in version control system like here.

By default the client will use bootstrap RPC server (for getting node address) provided by NKN. Any NKN full node can serve as a bootstrap RPC server. To create a client using customized bootstrap RPC server:

const client = nkn({
  identifier: 'any string',
  seedRpcServerAddr: 'https://ip:port',
});

Get client identifier:

console.log(client.identifier);

And client NKN address, which is used to receive data from other clients:

console.log(client.addr);

Listen for connection established:

client.on('connect', () => {
  console.log('Connection opened.');
});

Send text message to other clients:

client.send(
  'another client address',
  'hello world!',
);

You can also send byte array directly:

client.send(
  'another client address',
  Uint8Array.from([1,2,3,4,5]),
);

Or publish text message to a topic (subscribe is done through nkn-wallet-js):

client.publish(
  'topic',
  'hello world!',
);

Receive data from other clients:

// can also be async (src, payload, payloadType, encrypt) => {}
client.on('message', (src, payload, payloadType, encrypt) => {
  if (payloadType === nkn.PayloadType.TEXT) {
    console.log('Receive text message:', src, payload);
  } else if (payloadType === nkn.PayloadType.BINARY) {
    console.log('Receive binary message:', src, payload);
  }
  console.log('Message is', encrypt ? 'encrypted' : 'unencrypted');
});

If a valid data (string or Uint8Array) is returned at the end of the handler, the data will be sent back to sender as response:

client.on('message', (src, payload, payloadType, encrypt) => {
  return 'Well received!';
  // You can also return a byte array:
  // return Uint8Array.from([1,2,3,4,5]);
});

Note that if multiple onmessage handlers are added, the result returned by the first handler (in the order of being added) will be sent as response.

The send method will return a Promise that will be resolved when sender receives a response, or rejected if not receiving acknowledgement within timeout period. Similar to message, response can be either string or byte array:

client.send(
  'another client address',
  'hello world!',
).then((response) => {
  // The response here can be either string or Uint8Array
  console.log('Receive response:', response);
}).catch((e) => {
  // This will most likely to be timeout
  console.log('Catch:', e);
});

Client receiving data will automatically send an acknowledgement back to sender if no response is returned by any handler so that sender will be able to know if the packet has been delivered. From the sender's perspective, it's almost the same as receiving a response, except that the Promise is resolved without a value:

client.send(
  'another client address',
  'hello world!',
).then(() => {
  console.log('Receive ACK');
}).catch((e) => {
  // This will most likely to be timeout
  console.log('Catch:', e);
});

Timeout for receiving response or acknowledgement can be set when initializing client:

const client = nkn({
  responseTimeout: 5, // in seconds
});

or when sending a packet:

client.send(
  'another client address',
  'Hello world!',
  {
    responseTimeout: 5, // in seconds
  },
)

Check examples for full examples.

Can I submit a bug, suggestion or feature request?

Yes. Please open an issue for that.

Can I contribute patches?

Yes, we appreciate your help! To make contributions, please fork the repo, push your changes to the forked repo with signed-off commits, and open a pull request here.

Please sign off your commit. This means adding a line "Signed-off-by: Name " at the end of each commit, indicating that you wrote the code and have the right to pass it on as an open source patch. This can be done automatically by adding -s when committing:

git commit -s

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