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Agenda
- Why, When and What's Node.js?
- Node.js Hello World
- What's and how to use NPM
- Dependencies with Common.js
- Callbacks, callbacks and more callbacks
- Express.js to the rescue
- Going real time with Socket.io
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Why Node.js
Why, When and What's Node.js
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Why Node.js
Why, When and What's Node.js
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Why Node.js
Why, When and What's Node.js
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Why Node.js
Why, When and What's Node.js
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Companies using Node.js
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Why Node.js
Why, When and What's Node.js
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Why, When and What's Node.js
Why Node.js
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Callback
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Blocking I/O
Why Node.js
Why, When and What's Node.js
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Why Node.js
Why, When and What's Node.js
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How to scale ?
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When Node.js
Why, When and What's Node.js
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When Node.js
Why, When and What's Node.js
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What's Node.js
Why, When and What's Node.js
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NODE.JS SYSTEM ARCHITECTURE
What's Node.js
Why, When and What's Node.js
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What's Node.js
Why, When and What's Node.js
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What's Node.js: A Hello Node App
Why, When and What's Node.js
// See node-lessons/lesson_0/index.js
var http = require('http');
var PORT = process.env.PORT || 8080;
var HOSTNAME = process.env.HOSTNAME || 'localhost';
var NODE_ENV = process.env.NODE_ENV || 'development';
var counter=0;
var server = http.createServer(function(request, response) {
response.writeHead(200, {'Content-Type': 'text/html'});
response.write('<!DOCTYPE "html">');
response.write('<html>');
response.write('<head>');
response.write('<title>Hello Node Page</title>');
response.write('</head>');
response.write('<body>');
response.write('Hello Node.js ' + counter + ' running as ' + NODE_ENV + '!');
response.write('</body>');
response.write('</html>');
response.end();
console.log('counter: ' + counter + ' request url: ' + request.url);
counter++;
});
server.listen(PORT, HOSTNAME);
console.log('Server is listening at PORT:' + PORT);
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What are Node.js modules
Why, When and What's Node.js
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- 1 to 1 correspondence with 1 file
- Modules are loaded synchronously
- Modules are cached
-
Core modules come with the platform
-
ex: require('http')
-
-
3rd party modules are published as packages to a registry (such as NPM)
-
use:npm install
- installed into node_modules directory
-
-
File modules
- require path starts with '/', './', or '../'
How require(...) works?
Why, When and What's Node.js
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If not a core module, and not an explicit path (whether absolute or relative):
- Looks in module's directory for node_modules/
- if not found, continue searching each parent directory until file system root ( / )
- Throw an error (code: MODULE_NOT_FOUND)
How require(...) works?
Why, When and What's Node.js
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When requiring a path instead of an explicit file
- Look for package.json ("main" property)
- Look for index.js
EX: require('./my_awesome_lib')
Folder as module
// example content of ./my_awesome_lib/package.json
{ "name" : "my-awesome-library",
"main" : "./implementation/my_lib_impl.js" }
How require(...) works?
Why, When and What's Node.js
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Modules can be installed globally using:
- npm install -g [module_name]
But that's just recommended for Command Line Interface (CLI) modules
EX: npm install -g express-generator
If NODE_PATH is set with a single or multiple paths, Node.js will search there. Additionally it will also search in the following paths:
- $HOME/node_modules
- $home/node_library
- #prefix/lib/node
Global modules
No longer considered a good practice but still there for legacy support.
How require(...) works?
Why, When and What's Node.js
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More details at:
What's NPM
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"Do one thing well."
"Compose larger units out of smaller, independent units of functionality."
NPM filosofy
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Using NPM
# It shows up current NPM installed version
npm --version
# Initialize current folder creating
# a package.json file to store dependencies
npm init
# Shows up NPM configuration like used
# folders
npm config list
# List every globally installed module
npm list --g[lobal]
# List every locally installed module
npm list
# Locally installs express and also adds it
# to package.json
npm install express --save
# Locally installs specific modules but
#just for dev environments
npm install mocha chai --save-dev
# Installs all dependencies declared at
# package.json even dev dependencies
npm install
# Just installs non development
# specific dependencies.
npm install --production
# Locally uninstall a module
npm uninstall express
# Installs a particular module version
npm install underscore@1.8.2
# Updates a module but following what's
# configured at package.json
npm update underscore
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More about NPM
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THE SIMPLEST MODULE
Dependencies with Common.js
// See node-lessons/lesson_1/hello.js
console.log('Hello World');
// See node-lessons/lesson_1/app.js
require('./hello.js');
>node app.js
Hello World
>
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PATTERN 1: DEFINE A GLOBAL
Dependencies with Common.js
// See node-lessons/lesson_2/foo.js
foo = function () {
console.log('foo!');
}
// See node-lessons/lesson_2/foo.js
require('./foo.js');
foo();
>node app.js
foo!
>
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PATTERN 2: EXPORT AN ANONYMOUS FUNCTION
Dependencies with Common.js
// See node-lessons/lesson_3/bar.js
module.exports = function () {
console.log('bar!');
}
// See node-lessons/lesson_3/app.js
var bar = require('./bar.js');
bar();
>node app.js
bar!
>
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PATTERN 3: EXPORT A NAMED FUNCTION
Dependencies with Common.js
// See node-lessons/lesson_4/fiz.js
exports.fiz = function () {
console.log('fiz!');
}
// See node-lessons/lesson_4/app.js
var fiz = require('./fiz.js').fiz;
fiz();
>node app.js
fiz!
>
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PATTERN 4: EXPORT AN ANONYMOUS OBJECT
Dependencies with Common.js
// See node-lessons/lesson_5/buz.js
var Buz = function () {};
Buz.prototype.log = function () {
console.log('buz!');
};
module.exports = new Buz();
// See node-lessons/lesson_5/app.js
var buz = require('./buz.js');
buz.log();
>node app.js
buz!
>
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PATTERN 5: EXPORT A NAMED OBJECT
Dependencies with Common.js
// node-lessons/lesson_6/baz.js
var Baz = function () {};
Baz.prototype.log = function () {
console.log('baz!');
};
exports.Baz = new Baz();
// node-lessons/lesson_6/app.js
var baz = require('./baz.js').Baz;
baz.log();
>node app.js
baz!
>
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PATTERN 6: EXPORT AN ANONYMOUS PROTOTYPE
Dependencies with Common.js
// See node-lessons/lesson_7/doo.js
var Doo = function () {};
Doo.prototype.log = function () {
console.log('doo!');
}
module.exports = Doo;
// See node-lessons/lesson_7/app.js
var Doo = require('./doo.js');
var doo = new Doo();
doo.log();
>node app.js
doo!
>
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PATTERN 7: EXPORT A NAMED PROTOTYPE
Dependencies with Common.js
// See node-lessons/lesson_8/qux.js
var Qux = function () {};
Qux.prototype.log = function () {
console.log('qux!');
};
exports.Qux = Qux;
// See node-course/node-lessons/lesson_8/app.js
var Qux = require('./qux.js').Qux;
var qux = new Qux();
qux.log();
>node app.js
qux!
>
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exports VS module.exports
Dependencies with Common.js
module.exports.fiz = "fiz";
exports.buz = "buz";
module.exports === exports;
- exports is a reference to module.exports,
- node automatically creates it as a convenient shortcut.
- For assigning named properties, use either one.
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WARNING
Dependencies with Common.js
$ node
> module.exports.qux = "qux";
> exports
{ qux: "qux" }
> exports === module.exports
true
> exports = "wobble wibble wubble!";
> exports === module.exports
false
> exports
"wobble wibble wubble!"
> module.exports
{ qux: "qux" }
// module.exports is canonical
-
Assigning anything to exports directly (instead of exports.something) will overwrite exports reference so exports properties will not be seen from module.exports or available using require.
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Callback Hell / Bumeran Code /
Callbacks, callbacks and more callbacks
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Callbacks Hell / Bumeran Code
Callbacks, callbacks and more callbacks
// Improving code readability
function x (a) {
do_something(function(){
process(a);
});
}
// can be converted to this:
function x (a) {
do_something(y_maker(a)); // notice we're calling y_maker,
// not passing it in as callback
}
function y_maker (b) {
return function () {
process(b);
};
}
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Callbacks
Callbacks, callbacks and more callbacks
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Async.js to the rescue
Callbacks, callbacks and more callbacks
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Async provides around 70 functions that include the usual 'functional' suspects:
- map
- reduce
- filter
- each
- parallel
- series
- waterfall
As well as some common patterns for asynchronous control flow:
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Async.js : series
Callbacks, callbacks and more callbacks
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// See node-lessons/lesson_9/async_series.js
var async = require('async');
async.series([
function(callback){
console.log('1st function call starts.');
setTimeout(function(){
console.log('1st function call resolved.');
callback(null, 1); // err, result
}, 1000);
},
function(callback){
console.log('2nd function call starts.');
setTimeout(function(){
console.log('2nd function call resolved.');
callback(null, 2, 3); // err, results
}, 100);
}
],
function(err, results){
// err propagates all errors within the series functions
// results holds all the results, [1, [2, 3]] in this case
console.log('Results return in order as espected ;)');
console.dir(results);
});
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Async.js : parallel
Callbacks, callbacks and more callbacks
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// See node-lessons/lesson_9/async_parallel.js
var async = require('async');
async.parallel([
function(callback){
console.log('1st function call starts.');
setTimeout(function(){
console.log('1st function call resolved.');
callback(null, 1); // err, result
}, 1000);
},
function(callback){
console.log('2nd function call starts.');
setTimeout(function(){
console.log('2nd function call resolved.');
callback(null, 2); // err, result
}, 100);
}
],
function(err, results){
// err propagates all errors within the parallel functions
// results holds all the results, [1, 2] in this case
console.log('But results return in order as espected ;)');
console.dir(results);
});
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Async.js : waterfall
Callbacks, callbacks and more callbacks
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// See node-lessons/lesson_9/async_waterfall.js
var async = require('async');
var WINK = ';)';
var SMILEY = ':D';
var TONGUE = ':P';
async.waterfall([
function(callback){
console.log('1st function call starts.');
setTimeout(function(){
console.log('1st function call resolved.');
callback(null, WINK, SMILEY); // err, result, ... cascade params
}, 5000);
},
function(arg1, arg2, callback){
console.log(['2nd function call starts receiving arg1:',
arg1,
'and arg2:',
arg2,
'.'].join(' '));
setTimeout(function(){
console.log('2nd function call resolved.');
var prefix = 'result ';
callback(null,
prefix + TONGUE,
prefix + arg2,
prefix + arg1); // err, ... multiple results is ok
}, 3000);
}
],
function(err, result1, result2, result3){
// err propagates all errors within the waterfall functions
console.log('Important: waterfall can handle multiple results.');
console.dir(result1);
console.dir(result2);
console.dir(result3);
});
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More about Async.js?
Callbacks, callbacks and more callbacks
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Express.js to the rescue
https://github.com/subfuzion/express-demo
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Express.js to the rescue
# Installing Express in our project
npm install express --save
# Do you need a middleware for handling JSON, Raw, Text and URL encoded form data?
npm install body-parser --save
# Do you need a middleware to parse cookies from request headers and populate
# req.cookies with an object keyed by the cookie names?
npm install cookie-parser --save
# Do you need a middleware for handling multipart/form-data?
npm install multer --save
# Do you need session handling using cookie store?
npm install cookie-session --save
# Do you need server logs?
npm install morgan --save
# Do you need to serve static content (i.e. html pages, images, css)?
npm install serve-static --save
# Do you need an authentication library?
npm install passport --save
# Do you want CLI assistance to create your App?
# then globally install express and express-generator
npm install -g express express-generator
Preflight check on
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Express.js to the rescue
//server.js
var express = require('express');
var app = express();
app.get('/', function (req, res) {
res.send('Hello World');
})
var server = app.listen(8081, function () {
var host = server.address().address
var port = server.address().port
console.log("Example app listening at http://%s:%s", host, port)
})
First flight on Express.js
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See lesson_10 source code
See lesson_11 source code
Express.js to the rescue
What is Middleware
Middleware pattern is a series of processing units connected together, where the output of one unit is the input for the next one. In Node.js, this often means a series of functions in the form:
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function(request, response, next) {
// ... Run some code
next();
};
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request -> middleware1 -> middleware2 -> ...middlewareN -> route -> app -> response
Tipical Flow:
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Express.js to the rescue
Applying Express middleware
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var express = require('express');
var app = express();
//... Define middleware1-N
app.use(middleware1);
app.use(middleware2);
...
app.use(middlewareN);
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Express.js to the rescue
Middleware order
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var express = require('express');
var logger = require('morgan');
var bodyParser = require('body-parser');
var app = express();
...
app.use(logger('dev'));
app.use(bodyParser.json());
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Middlewares are executed in the specified order:
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Express.js to the rescue
Two Categories of Express Middleware
- npm modules, e.g., body-parser
- Custom Middleware
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See lesson_13 source code for an express-generator example
Express.js to the rescue
Custom Middleware
Creating a Custom Middleware using a reference
Creating a Custom Middleware with anonymous function definition
...
var middleware = function (request, response, next) {
// Modify request or response
// Execute the callback when done
next();
};
...
app.use(middleware);
app.use(function (request, response, next) {
// Modify request or response
// Execute the callback when done
next();
});
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Express.js to the rescue
Template Engines
Some examples
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Express.js to the rescue
Template Engines
Express.js uses by default
PUG ???... really? ... well ... yes
JADE
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Express.js to the rescue
Template Engines: JADE
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Express.js to the rescue
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Template Engines: JADE/PUG
//-index.jade
doctype html
html(lang="en")
head
title= pageTitle
script(src="/scripts/force.js")
script.
var useTheForce = force.use();
body
h2 These aren't the droids you're looking for
#container.col
p -You can go about your busines.
p -Move along.
May the force be with you and move to node-lessons/lesson_12
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Collection
Document
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MongoDB query
Typical SQL query
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MongoDB query with projection control
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MongoDB insert
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MongoDB update
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MongoDB remove
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MongoDB aggregated query
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MongoDB map reduce query
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MongoDB documents relationship
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var mongoose = require('mongoose');
var Schema = mongoose.Schema;
// create a schema
var userSchema = new Schema({
name: String,
username: { type: String, required: true, unique: true },
password: { type: String, required: true },
admin: Boolean,
location: String,
meta: {
age: Number,
website: String
},
created_at: Date,
updated_at: Date
});
// the schema is useless so far
// we need to create a model using it
var User = mongoose.model('User', userSchema);
// make this available to our users in our Node applications
module.exports = User;
Mongoose
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// if our user.js file is at app/models/user.js
var User = require('./app/models/user');
// create a new user called chris
var chris = new User({
name: 'Chris',
username: 'sevilayha',
password: 'password'
});
// call the custom method. this will just add -dude to his name
// user will now be Chris-dude
chris.dudify(function(err, name) {
if (err) throw err;
console.log('Your new name is ' + name);
});
// call the built-in save method to save to the database
chris.save(function(err) {
if (err) throw err;
console.log('User saved successfully!');
});
Mongoose
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Socket.io main objective
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Socket.io main objective is to enable real time applications on any browser
- Socket between Server & Client
- Send data between clients
- Receive event based data
- Supports almost any browser
- Supports Multiple sockets on a single connection
- Detects disconnection using heartbits
- 100% javascript
- Available on NPM
Socket.io typical usage
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Socket.io is real time
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Socket.io fallback methods
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Socket.io handshake
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client socket.io
Node.js server + socket.io
Socket.io handshake
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client socket.io
Node.js server + socket.io
transport getway, id and config are returned
Socket.io handshake
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client socket.io
Node.js server + socket.io
Heartbeats sent to secure connection healt
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client stablish a realtime connection with server
Basic server setup
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var io = require('socket.io').listen(80);
io.sockets.on('connection', function (socket){
socket.emit('helloworld', { hello: 'world' });
socket.on('other event', function (data) {
console.log(data);
});
});
Basic client setup
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<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect('http://localhost');
socket.on('news', function (data) {
console.log(data);
socket.emit('other event', { the: 'data' });
});
</script>
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?
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Thanks
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Node.js FUNdamentals (short version)
By Leonardo Daniel Otero
Node.js FUNdamentals (short version)
- 869