Node.js Http2ServerResponse.writeHead() Method

The Http2ServerResponse.writeHead() is an inbuilt application programming interface of the class Http2ServerResponse within the http2 module which is used to send the response header to the request.

Syntax:

response.writeHead(statusCode[, statusMessage][, headers])

Parameters: This method accepts the following argument as a parameter.

• statusCode: It is the 3-digit HTTP status code.
• statusMessage: It is a human-readable status message. It is an optional parameter.
• headers: This is the response header passed as a parameter. It is an optional parameter.

Return Value: This method has nothing to return.

How to generate a Private key and Public certificate?

1. Filename: Private key

Open notepad and copy-paste the following key and save the file as private-key.pem

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

2. Filename: Public certificate

Open notepad and copy-paste the following key and save the file as public-cert.pem

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Example 1: Filename: index.js

// Node.js program to demonstrate the
// Http2ServerResponse.writeHead() method
const http2 = require('http2');
const fs = require('fs');

// Private key and public certificate for access
const options = {
    key: fs.readFileSync('private-key.pem'),
    cert: fs.readFileSync('public-cert.pem'),
};

// Request and response handler
const http2Handlers = (request, response) => {

    // Sending the data to the client
    // by using response.writeHead() method
    response.writeHead(200, {
        'Content-Length': Buffer.byteLength('hello world'),
        'Content-Type': 'text/plain; charset=utf-8'
    });

    // Sending the signal to the client
    response.end("hello world")
};

// Creating and initializing server
// by using http2.createServer() method
const server = http2.createServer(options, http2Handlers);

server.on('stream', (stream, requestheader) => {
    stream.write('hello ');

    // Getting all information of this http2stream object
    // by using state method
    const status = stream.state;

    stream.end("priority weight : " + status.weight);

    // Stopping the server
    // by using the close() method
    server.close(() => {
        console.log("server destroyed");
    })
});

server.listen(8000);

// Creating and initializing client
// by using tls.connect() method
const client = http2.connect('http://localhost:8000');

const req = client.request({ 
    ':method': 'GET', ':path': '/' });

req.on('response', (responsesocket) => {
    console.log(responsesocket);
});

req.on('data', (data) => {
    console.log('Received: %s ',
    data.toString().replace(/(\n)/gm, ""));
});

req.on('end', () => {
    client.close(() => {
        console.log("client destroyed");
    })
});

Run the index.js file using the following command:

node index.js

Output:

[Object: null prototype] {
  ':status': 200,
  'content-length': '11',
  'content-type': 'text/plain; charset=utf-8',
  date: 'Sun, 06 Dec 2020 14:12:00 GMT'
}
Received: hello world
client destroyed
server destroyed

Example 2: Filename: index.js

// Node.js program to demonstrate the
// Http2ServerResponse.writeHead() method
const http2 = require('http2');
const fs = require('fs');

// Private key and public certificate for access
const options = {
    key: fs.readFileSync('private-key.pem'),
    cert: fs.readFileSync('public-cert.pem'),
};

// Request and response handler
const http2Handlers = (request, response) => {

    // Sending the data to the client
    // by using response.writeHead() method
    response.writeHead(200, {
        'Content-Length': Buffer.byteLength('hello world'),
        'Content-Type': 'text/plain; charset=utf-8'
    });

    // Sending the signal to client
    response.end("hello world")
};

// Creating and initializing server
// by using http2.createServer() method
const server = http2.createServer(
    options, http2Handlers);

server.on('stream', (stream, requestheader) => {

    // Stopping the server
    // by using the close() method
    server.close(() => {
        console.log("server destroyed");
    })
});

server.listen(8000);

// Creating and initializing client
// by using tls.connect() method
const client = http2.connect(
    'http://localhost:8000');

const req = client.request({ 
    ':method': 'GET', ':path': '/' });

req.on('response', (responsesocket) => {
    console.log(responsesocket);
});

req.on('end', () => {
    client.close(() => {
        console.log("client destroyed");
    })
});

Run the index.js file using the following command:

node index.js

Output:

[Object: null prototype] {
  ':status': 200,
  'content-length': '11',
  'content-type': 'text/plain; charset=utf-8',
  date: 'Sun, 06 Dec 2020 14:39:31 GMT'       
}

Reference: 

https://nodejs.org/dist/latest-v12.x/docs/api/http2.html#http2_response_writehead_statuscode_statusmessage_headers