Node.js Patterns and Opinions

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Node.js: Patterns and Opinions
Isaac Z. Schlueter – TxJS 2013
Monday, April 15, 13

SUPER FAST
NODE INTROomg!
Monday, April 15, 13

WTF is a Node.js?
•JavaScript on the Server
(or robots, helicopters, any other not-a-web-browser thing)
•Non-blocking I/O
...

conventional program
printLine('Enter your name:')
var name = getLine();
var r = db.save(name);
if (r === 'ok')
printLine(...

conventional program
printLine('Enter your name:')
// waiting for I/O to happen!
var name = getLine();
// omg soooo sllllo...

callbacks!
printLine('Enter name:', function() {
getLine(function(err, name) {
db.save(name,function(err, r) {
if (r === '...

NOT ANY FASTER!
maybe a little bit slower, actually
Monday, April 15, 13

Non-blocking I/O is not about
making I/O faster
•It's about making I/O not prevent other I/O
•Doing things in this way add...

Callback Drawbacks
•Stack gets unwound - Error().stack doesn't tell you much
•try/catch can't wrap throws effectively
•Boi...

THREADS
Monday, April 15, 13

Node is
"single-threaded"
Monday, April 15, 13

Node actually has a lot of
internal threads, but...
•Only one thread is running JavaScript
•That means that your JS will n...

COROUTINES
Monday, April 15, 13

Coroutines
•Cooperative Multitasking with yield and await keywords
•No preemption issues, same while(true); behavior
•Stac...

LET'S HTTP!
Monday, April 15, 13

hello,TxJS
require('http').createServer(
function(req, res) {
res.end('hello, txjs!')
}
).listen(80)
Monday, April 15, 13

Callbacks for
EVERYTHING?
gotta be elfin kidding me...
Monday, April 15, 13

no, we're not jerks.
•callback: lowest Node abstraction for doing one async thing
•EventEmitter: for things that happen co...

cb vs ee
•callback: "Show me all the blueprints"
•EventEmitter: "Any time you get blueprints, show me them"
way of the fut...

EventEmitter
var e = new EventEmitter();
e.on('foo', function(arg) {
console.log('baz' + arg)
});
e.emit('foo', 'bar');
//...

hello, EventEmitter
var s = new http.Server()
s.on('request', function(req, res){
res.end('hello, txjs!')
})
s.listen(80)
...

Streams
•When managing data flows, control throughput or ENOMEM
•Streams are a special EventEmitter that takes care of thi...

OPINIONS
Monday, April 15, 13

JavaScript
Monday, April 15, 13

JavaScript
Monday, April 15, 13

Node is JavaScript
•Node is not a language - JavaScript is the language
•Portability, Events, Run to completion:The JavaSc...

Errors must
be handled
Monday, April 15, 13

Do not ignore errors
•Callbacks all get an error object as their first argument
•EventEmitter 'error' event is magical... ...

Monday, April 15, 13

Monday, April 15, 13

Portability++
Monday, April 15, 13

Increase Portability
•libuv: Evented nonblocking I/O for Computers
•If you write JavaScript, it'll run on every OS Node ru...

Slowness
is a Bug
Monday, April 15, 13

Slowness is a Bug
•Latency is far and away the most important metric
(Some would say, the only important metric!)
•Unneces...

Unix
Monday, April 15, 13

Unix Philosophy
•Interfaces should be obvious, simple, composible, consistent
•Callback => EventEmitter => Stream
•Portabi...

Assemble
Monday, April 15, 13

Assemble rather than invent
•JavaScript is old
•Nonblocking I/O is ancient
•Unix is paleolithic
•Put proven things togethe...

Small Parts
Monday, April 15, 13

Small Core, Small Parts
•The scope of node's core API is much smaller than
comparable server runtimes
•No glob, no xml, et...

Community
Monday, April 15, 13

Node is a Community
•Everyone is an npm publisher. Everyone is a collaborator.
•Minimum Necessary Process: Governance most...

Monday, April 15, 13

Compassionate
Communities
Monday, April 15, 13

EGO
Monday, April 15, 13

JIFASNIF
Monday, April 15, 13

JIFASNIF
•JavaScript is fun, and so Node is fun.
•When making a decision, always choose the funner option
•"Fun" is a very...

FUTURE
Monday, April 15, 13

v0.12
•Massive cleanup of HTTP interfaces (especially client)
•General purpose socket pooling interface
•Faster TLS (espec...

v1.0.0
•The next stable release after 0.12 (probably)
•Incremental improvements, uv/npm/V8 upgrades
•Not much in the way o...

See you on
the Internet!
http://j.mp/node-patterns-pdf
Monday, April 15, 13

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