Uno sguardo alle tecnologie usate fino ad oggi per gestire l'asincronia in javascript e quali saranno le tecnologie in futuro.

1. #dotbari

2. Giuseppe Santoro
ApuliaSoft

3. Gestire l'asincronia in
JavaScript
uno sguardo al futuro!

4. C’era una volta

5. $conn = $db.connect(‘localhost:1234’);
$user = $conn.query(‘SELECT . . .’);
$user.name = ‘Pippo’;
$user.save();
echo(‘salvato’);

6. Apache Server
t1
Richiesta Creazione di 1 thread

7. Apache Server
t1
t2
2 richieste Creazione di 2 threads

8. Apache Server
t1
t2
t3
t4
4 richieste Creazione di 4 threads

9. $conn = $db.connect(‘localhost:1234’);
$user = $conn.query(‘SELECT . . .’);
$user.name = ‘Pippo’;
$user.save();
echo(‘salvato’);

10. $conn = $db.connect(‘localhost:1234’);
$user = $conn.query(‘SELECT . . .’);
$user.name = ‘Pippo’;
$user.save();
echo(‘salvato’);

11. var conn = db.connect(‘localhost:1234’);
var user = conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
user.save();
console.log(‘salvato’);

12. var conn = db.connect(‘localhost:1234’);
var user = conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
user.save();
console.log(‘salvato’);

13. var conn = db.connect(‘localhost:1234’);
var user = conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
user.save();
console.log(‘salvato’);

14. var conn = db.connect(‘localhost:1234’);
var user = conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
user.save();
console.log(‘salvato’);

15. var conn = db.connect(‘localhost:1234’);
var user = conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
user.save();
console.log(‘salvato’);

16. t1
1 richiesta 1 thread

17. t1
2 richieste 1 thread

18. t1
4 richieste 1 thread

19. t1
4 richieste 1 thread

20. Node.js

21. var conn = db.connect(‘localhost:1234’);
var user = conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
user.save();
console.log(‘salvato’);

22. ‘il passato’: CALLBACK

23. var conn = db.connect(‘localhost:1234’);

24. var conn = db.connect(‘localhost:1234’);
db.connect(‘localhost:1234’, function(err,conn){
// async code
});
// code code code code

25. db.connect(‘localhost:1234’, function(err,conn){
conn.query(‘SELECT...’, function(err,user){
user.name = ‘Pippo’;
user.save(function(err){
console.log(‘salvato’);
});
});
});

26. db.connect(‘localhost:1234’, function(err,conn){
if (err) return console.log(‘errore’);
conn.query(‘SELECT...’, function(err,user){
if (err) return console.log(‘errore’);
user.name = ‘Pippo’;
user.save(function(err){
if (err) return console.log(‘errore’);
console.log(‘salvato’);
});
});
});

27. ‘il presente’: PROMISE

28. var conn = db.connect(‘localhost:1234’);

29. var conn = db.connect(‘localhost:1234’);
var promisedConn = db.connect(‘localhost:1234’);
// code code code code
promisedConn.then(function(conn){
// async code
});
// code code code code

30. var conn = db.connect(‘localhost:1234’);
var promisedConn = db.connect(‘localhost:1234’);
// code code code code
promisedConn.then(function(conn){
// async code
}).then(function(val){});
// code code code code

31. IDEA: chaining

32. db.connect(‘localhost:1234’)
.then(function(conn){
return conn.query(‘SELECT...’);
}).then(function(user){
user.name = ‘Pippo’;
return user.save();
}).then(function(){
console.log(‘salvato’);
});

33. db.connect(‘localhost:1234’)
.then(function(conn){
return conn.query(‘SELECT...’);
}).then(function(user){
user.name = ‘Pippo’;
return user.save();
}).then(function(){
console.log(‘salvato’);
}).fail(function(){
console.log(‘errore’);
});

34. ‘il futuro’: GENERATOR

35. yield

36. function count(n){
var res = []
for (var x = 0; x < n; x++) {
res.push(x)
}
return res
}
for (var x of count(5)) {
console.log(x)
}

37. function* count(n){
for (var x = 0; x < n; x++) {
yield x
}
}
for (var x of count(5)) {
console.log(x)
}

38. co(function *(){
var a = yield get('http://google.com');
var b = yield get('http://yahoo.com');
})()
co(function *(){
var c = yield get('http://apple.com');
var d = yield get('http://microsoft.com');
})()

39. var conn = db.connect(‘localhost:1234’);
var user = conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
user.save();
console.log(‘salvato’);

40. co(function *(){
var conn = yield db.connect(‘localhost:1234’);
var user = yield conn.query(‘SELECT . . .’);
user.name = ‘Pippo’;
yield user.save();
console.log(‘salvato’);
})();

41. Compatibilita’
0.11.131
$ node -harmony [filename]

42. Compatibilita’

43. Compatibilita’

44. Grazie per l’ascolto
Domande ? ?