node-parse-rss
A quick node.js RSS feed parser.
Original question: http://stackoverflow.com/questions/20177259/requesting-rss-feeds-from-two-web-sites-in-node-js Saw this question on Stack Overflow and decided it merited a quick answer.
Try it yourself
DIY
Clone/copy this repo to your local machine:
git clone https://github.com/nelsonic/node-parse-rss.gitInstall the modules:
npm installRun the node script
node article-stream.jsPoint your browser at: http://localhost:5000
You will expect to see something like:
Yes, this is not beautiful. But the question was specific to the technical side of how to parse the RSS feeds not a full (attractive) solution. That is an "exercise left to the reader"... :-)
Solution
The Original Question on StackOverflow (async)
var feed = require('feed-read');
var http = require('http');
var async = require('async');
var request = require('request');
var LIMIT = 10;
var UNABLE_TO_CONNECT = "Unable to connect.";
var BBC_URL = 'http://feeds.bbci.co.uk/news/rss.xml';
var SKY_URL = 'http://news.sky.com/feeds/rss/home.xml';
var server = http.createServer(onRequest);
server.listen(9000);
function onRequest(req, res) {
res.writeHead(200, {
'Content-Type' : 'text/html; charset=utf-8'
});
async.parallel([ function(callback) {
feed(BBC_URL, onRssFetched);
// TODO: where to call callback()?
}, function(callback) {
feed(SKY_URL, onRssFetched);
// TODO: where to call callback()?
} ], function done(err, results) {
console.log("Done");
if (err) {
throw err;
}
});
}
function onRssFetched(err, articles) {
console.log("RSS fetched");
var html = [];
if (err) {
html.push("<p>", UNABLE_TO_CONNECT = "</p>");
} else {
html.push("<ol>");
var i = 0;
articles.forEach(function(entry) {
if (i == LIMIT) {
return;
}
html.push("<li><a href='" + entry.link + "'>" + entry.title
+ "</a></li>");
i++;
});
}
console.log(html.join(""));
}The author also posted it on LinkedIn: http://www.linkedin.com/groups/Parse-RSS-feeds-using-Nodejs-2906459.S.5811745652475990020
Parsing Multiple RSS Feeds Without Async
The async module is the hammer of the node.js world.
(read: Law of the Instrument)
I see async.parallel used everywhere to force asynchronous requests
to wait until all responses have returned before performing a final action.
There's another (better?) way of doing it... but it requires more work.
Create an Array of RSS Feed URls
Rather than having a separate variable for each RSS feed, we put them in an array. This allows us to itterate over the urls array and fetch each RSS feed. It makes it easy to add/remove feeds without having to touch the application logic.
urls = [
"http://feeds.bbci.co.uk/news/rss.xml",
"http://news.sky.com/feeds/rss/home.xml"
]; // Example RSS FeedsCreate an Http Write Stream to Client
Because the node.js http (core) module supports streams natively, we can stream the news articles to the client individually:
http.createServer(function (req, res) {
// send basic http headers to client
res.writeHead(200, {
"Content-Type": "text/html",
"Transfer-Encoding": "chunked"
});
// setup simple html page:
res.write("<html>\n<head>\n<title>RSS Feeds</title>\n</head>\n<body>");
// loop through our list of RSS feed urls
for (var j = 0; j < urls.length; j++) {
// fetch rss feed for the url:
feed(urls[j], function(err, articles) {
// loop through the list of articles returned
for (var i = 0; i < articles.length; i++) {
// stream article title (and what ever else you want) to client
res.write("<h3>"+articles[i].title +"</h3>");
// check we have reached the end of our list of articles & urls
if( i === articles.length-1 && j === urls.length-1) {
res.end("</body>\n</html>"); // end http response
} // else still have rss urls to check
} // end inner for loop
}); // end call to feed (feed-read) method
} // end urls for loop
}).listen(5000);putting it all together we get:
var feed = require('feed-read'), // require the feed-read module
http = require("http"),
urls = [
"http://feeds.bbci.co.uk/news/rss.xml",
"http://news.sky.com/feeds/rss/home.xml",
"http://www.techmeme.com/feed.xml"
]; // Example RSS Feeds
http.createServer(function (req, res) {
// send basic http headers to client
res.writeHead(200, {
"Content-Type": "text/html",
"Transfer-Encoding": "chunked"
});
// setup simple html page:
res.write("<html>\n<head>\n<title>RSS Feeds</title>\n</head>\n<body>");
// loop through our list of RSS feed urls
for (var j = 0; j < urls.length; j++) {
// fetch rss feed for the url:
feed(urls[j], function(err, articles) {
// loop through the list of articles returned
for (var i = 0; i < articles.length; i++) {
// stream article title (and what ever else you want) to client
res.write("<h3>"+articles[i].title +"</h3>");
// check we have reached the end of our list of articles & urls
if( i === articles.length-1 && j === urls.length-1) {
res.end("</body>\n</html>"); // end http response
} // else still have rss urls to check
} // end inner for loop
}); // end call to feed (feed-read) method
} // end urls for loop
}).listen(5000);Let me know your thoughts on this! I'd love to hear if you have a
better way of doing it! :-)
Background
From the original code on StackOverflow Maksim is using the following non-core node modules:
- async: https://github.com/caolan/async
- request: https://github.com/mikeal/request
- feed-read: https://github.com/sentientwaffle/feed-read
The firts two (async and request) are uber popular node modules that have been tested by thousands of people and used in many high-profile projects.
feed-read on the other hand ...
only 5 watchers at the time of writing (not v. popular) and it was last updated 2 years ago ... (might not be compatible with the latest version of node.js or its dependencies!) but it does have unit tests which is a good sign so lets try it!
Read Documentation (Readme & Unit Tests)
Often developers neglect to document their work adequately in the README.md If this is the case, the best way of learning how to use a new module is to read through the unit tests in the ./test folder in the case of feed-read
https://github.com/sentientwaffle/feed-read/blob/master/test/index.test.js
The tests are very clear. And the module is well written.
I sent a clarifying question on LinkedIn: http://lnkd.in/dY2Xtf6
Meanwhile @GoloRoden gave an answer on Stack: http://stackoverflow.com/a/20273797/1148249
async.parallel({
bbc: function (callback) {
feed(BBC_URL, callback);
},
sky: function (callback) {
feed(SKY_URL, callback);
}
}, function (err, result) {
if (err) {
// Somewhere, something went wrong…
}
var rssBbc = result.bbc,
rssSky = result.sky;
// Merge the two feeds or deliver them to the client or do
// whatever you want to do with them.
});This answer requires the Async Module...
What if we instead try and write one without relying on async (for once)?