Getting started with node.js using http://current.thisismedium.com as a sample application.

1. Current
@robrighter

2. What is Node.js?
_ non-blocking
_ evented
_ javascript
@robrighter

3. Why is node useful?
@robrighter

4. Why is node useful?
It can handle a ton of
concurrent connections
@robrighter

5. A Gross
Oversimplification
of HTTP
Give me a page
Sure
Connection Closed
@robrighter

6. AJAX Polling
Got any updates?
No
Connection Closed
Got any updates?
No
Connection Closed
@robrighter

7. Comet
Got any updates?
...wait
Yes
Connection Closed
@robrighter

8. Websocket
asyncronous updates
@robrighter

9. Evented Programming
@robrighter

10. Non-Evented Example
mysql_select_db("example", $con);
$result = mysql_query("SELECT * FROM user WHERE fname='Bill'");
while($row = mysql_fetch_array($result)){
echo $row['fname'];
}
@robrighter

11. Evented Example
fs.readFile("./file", function (err, data) {
if (err) throw err;
sys.puts(data);
});
@robrighter

12. An Example
@robrighter

13. Server Side
@robrighter

14. Setup the Data Source
var rb = new lpb.LongPollingBuffer(70);
var dump = process.createChildProcess("tcpdump",["-i","en1","-A","-n","port", "80"]);
var ignorelist = ['localhost','foxnews.com'];
//Setup the listener to handle the flow of data from the dump
dump.addListener("output", function (data) {
var hosts = data.match(/Host: (.*)/g);
if(hosts){
_.each(hosts, function(item){
var out = item.slice(6);
sys.puts(out);
if(!_.detect(ignorelist, function(s){ return (item.indexOf(s) > -1); })){
rb.push(out);
}
});
}
});
@robrighter

15. LongPollingBuffer
DATA ARRAY
DATA: 1 1 1 0 1 0 0 1 1 0
OFFSET: 0 2 3 4 5 6 7 8 9 10
CLIENT ONE CLIENT TWO
@robrighter

16. Setup the Updater
fu.get("/update", function (req, res) {
//Send the HTTP Headers
res.sendHeader(200,{"Content-Type": "text/html"});
//Parse out the since from the query string
var thesince;
if(url.parse(req.url,true).hasOwnProperty('query') &&
url.parse(req.url,true).query.hasOwnProperty('since')){
thesince = parseInt(url.parse(req.url,true)['query']['since']);
}
else {
thesince = -1;
}
//Setup the datalistener (note why this works so well with JS scoping)
rb.addListenerForUpdateSince(thesince, function(data){
var body = '['+_.map(data,JSON.stringify).join(',n')+']';
res.write( body );
res.close();
});
});
@robrighter

17. Client Side
@robrighter

18. Long Polling Request
var url = “/update?since=” + lastrecieved;
$.getJSON(url, function(data){
var itemstoadd = _.map(data.reverse(),function(item){
lastrecieved = item["offset"];
return domainmarkup(item['value']);
});
var uc = $("#updatedcontent");
_.map(itemstoadd, function(item){
if(!interrupt){
uc.prepend(item);
}
});
setTimeout('getupdate(lastrecieved)', 1000);
});
@robrighter

19. Questions?
github.com/robrighter
twitter.com/robrighter
@robrighter