Node.js Server without Express
In the previous post, I demonstrated how to write a minimal http server in Node.js without using any framework to serve static content. In this post, I have enhanced the code to serve dynamic content as well.
Why?
- Why not?
- Express, though it claims to be un-opinionated — is opinionated.
- I wanted to write a simple server whose job is to just serve the content and let the handler(s) decide what to do with the content.
The Code
Here’s the complete code for the server.
Place this code in./minimal-dynamic-http-server/index.js
// Dependencies
const http = require('http');
const path = require('path');
const fs = require('fs');
const url = require('url');// Container Object
const server = {};// Base directory - Assuming minimal-dynamic-http-server will
// be accessed from its own folder
const baseDir = path.join(__dirname, '../');/**
* HANDLE STATIC CONTENT
*/// Allowed Mime types for static content
const mimeTypes = {
'.html': 'text/html',
'.jgp': 'image/jpeg',
'.css': 'text/css',
'.js': 'text/javascript',
'.png': 'image/png',
'.ico': 'image/x-icon',
'.json': 'application/json',
};/**
* Get the content type for a given path
* @param {string} url - url extracted from request.url
*/
server.getContentType = url => {
// Set the default content type to application/octet-stream
let contentType = 'application/octet-stream'; // Get the file extension
const extname = path.extname(url); // Set the contentType based on the mime type
for (let key in mimeTypes) {
if (mimeTypes.hasOwnProperty(key)) {
if (extname === key) {
contentType = mimeTypes[key];
}
}
}
return contentType;
};/**
* Serve the static content
* @param {string} pathname - request.url eg: /public/index.html
* @param {Object} response - response object
*/
server.serveStaticContent = (pathname, response) => {
// Get content type based on the file extension
const contentType = server.getContentType(pathname); // Set the Content-Type response header
response.setHeader('Content-Type', contentType); // Read the file and send the response
fs.readFile(`${baseDir}${pathname}`, (error, data) => {
if (!error) {
response.writeHead(200);
response.end(data);
} else {
response.writeHead(404);
response.end('404 - File Not Found');
}
});
};/**
* HANDLE DYNAMIC CONTENT
*
*//**
* Object to hold allowed dynamic paths.
* Use the setAllowedPaths() public method to set the dynamic paths
* and the corresponding handlers.
* {string}path/{function}handler
* Example:
* allowedPaths = {
* '/api/somepath': somehandler,
* '/api/anotherpath': anotherhandler
* }
*/
let allowedPaths = {};/**
* If incoming path is one of the allowed dynamic paths
* then return the path, otherwise return false
* @param {string} path
*/
server.getAllowedDynamicPath = path => {
for (const key in allowedPaths) {
if (allowedPaths.hasOwnProperty(key)) {
if (path === key) {
return path;
}
}
}
return false;
};/**
* Serve the dynamic content
* @param {string} pathname - dynamic path
* @param {Object} response - response object
*
*/
server.serveDynamicContent = (request, response) => {
// Retrieve the HTTP method
const method = request.method.toLowerCase();
// Parse the incoming request url
const parsedUrl = url.parse(request.url, true);
// Retrieve the pathname and query object from the parsed url
const { pathname, query } = parsedUrl; // buffer holds the request body that might come with a POST or
// PUT request.
let buffer = []; request.on('error', error => {
console.log('Error Occurred', error);
response.writeHead(500);
response.end('Error occurred:', error);
}); request.on('data', chunk => {
buffer.push(chunk);
}); request.on('end', () => {
buffer = Buffer.concat(buffer); // response data object to pass to the handler function
const responseData = {
method,
pathname,
query,
buffer,
}; // Retrieve the handler for the path
const handler = allowedPaths[pathname];
/**
* Call the handler for the path
* @param {Object} responseData
* @param {function} callback function definition
*
*/
handler(responseData, (statusCode = 200, data = {}) => {
response.writeHead(statusCode);
response.end(data);
});
});
};/**
* CREATE SERVER INSTANCE
*
*/
const httpServer = http.createServer((request, response) => {
const pathname = url.parse(request.url, false).pathname;
const dynamicPath = server.getAllowedDynamicPath(pathname); if (dynamicPath) {
server.serveDynamicContent(request, response);
} else {
server.serveStaticContent(pathname, response);
}
});/**
*
* PUBLIC METHODS
*
*//**
* Set allowed paths
* @param {Object} paths - Object containing all the allowed paths
*/
server.setAllowedPaths = paths => {
allowedPaths = paths;
};/**
* Main method to start the server
* @param {integer} port - default value 3000
* @param {string} host - default value 127.0.0.1
*
*/
server.init = (port = 3000, host = '127.0.0.1') => {
httpServer.listen(port, host, () => {
console.log(`Server is listening at http://${host}:${port}`);
});
};// Export module
module.exports = server;
Sample Usage
Write the following code in ./app.js
// Import the server code
const server = require('./minimal-dynamic-http-server');/**
* Handlers
*/// handler for '/api/abc' dynamic path
const abcHandler = (responseData, callback) => {
// Code goes here... //Pass statusCode and response to the callback function.
callback(200, '{"foo":"bar"}');
}// handler for '/api/def' dynamic path
const defHandler = (responseData, callback) => {
// Code goes here... callback(200, '{"message":"Have a nice day!"}');
}// Define the dynamic paths and handlers
const paths = {
'/api/abc': abcHandler,
'/api/def': defHandler
};// Set the dynamic paths
server.setAllowedPaths(paths);// Start the server
server.init(3500);
Run the code
$ node app.js// Expected Output
// Server is listening at http://127.0.0.1:3500$ curl http://localhost:3500/api/abc// Expected Output
// {"foo":"bar"}$ curl http://localhost:3500/api/def// Expected Output
// {"message":"Have a nice day!"}
Code Explained
Let us start with creating an instance of the server
/**
* CREATE SERVER INSTANCE
*
*/
const httpServer = http.createServer((request, response) => {
const pathname = url.parse(request.url, false).pathname;
const dynamicPath = server.getAllowedDynamicPath(pathname); if (dynamicPath) {
server.serveDynamicContent(request, response);
} else {
server.serveStaticContent(pathname, response);
}
});
First, we check if the incoming request is for dynamic content. We call server.getAllowedDynamicPath(), which scans through all the allowed dynamic paths and returns a path if a match is found. Method returns false if a match is not found.
If dynamicPath === false, then we assume the request is for static content and call the server.serveStaticContent() method.
If a dynamic path is found, we call the server.serveDynamicContent() method and pass the request and response objects as arguments.
Serve Dynamic Content
/**
* Serve the dynamic content
* @param {string} pathname - dynamic path
* @param {Object} response - response object
*
*/
server.serveDynamicContent = (request, response) => {
// Retrieve the HTTP method
const method = request.method.toLowerCase();
// Parse the incoming request url
const parsedUrl = url.parse(request.url, true);
// Retrieve the pathname and query object from the parsed url
const { pathname, query } = parsedUrl; // buffer holds the request body that might come with a POST or
// PUT request.
let buffer = []; request.on('error', error => {
console.log('Error Occurred', error);
response.writeHead(500);
response.end('Error occurred:', error);
}); request.on('data', chunk => {
buffer.push(chunk);
}); request.on('end', () => {
buffer = Buffer.concat(buffer); // response data object to pass to the handler function
const responseData = {
method,
pathname,
query,
buffer,
}; // Retrieve the handler for the path
const handler = allowedPaths[pathname];
/**
* Call the handler for the path
* @param {Object} responseData
* @param {function} callback function definition
*
*/
handler(responseData, (statusCode = 200, data = {}) => {
response.writeHead(statusCode);
response.end(data);
});
});
};
In server.serveDynamicContent() we retrieve method, pathname, and query from the incoming request. Then we check if the request came in with any data. If there is data, we push the data to abuffer.
We then create a responseData object with method, pathname, query, and buffer.
Next, we retrieve the handler function and call it with responseData as its first argument. Second argument is a callback function definition that handles the response object.
Serve Static Content
Check out my previous article to find out how static content is served.
Conclusion
The server written here has only one responsibility — serve content.
You pass all your dynamic paths and handlers in an object to the server. Your handlers are responsible for checking the http method, dealing with queries, parsing incoming data, etc.
Following is some information about lines of code, in case you’re wondering!
Total lines of code with comments: ~208 (5 KB)
Total lines of code without comments: ~97 (3 KB)
