Johannes Schlüter

In a few previous blog posts I was already talking about changes in PHP's trunk, like some BC break or some new features, time to continue:

JSON is the modern data format used in "AJAX" applications. As the leading language for the Web PHP course has support for handling JSON data: You can pass any data to json_encode() and the function will create a JSON representation of this data:

<?php
echo json_encode(array(1,2,3,4));
?>

[1,2,3,4]

This also works for objects:

<?php
$o = new stdclass;
$o->a = 42;
echo json_encode($o);
?>

{"a":42}

Wonderful. But the world isn't that easy. For many PHP objects the JSON-representation of the data is a bit more complex.for instance what about private properties or maybe you want to calculate some inner values? - In PHP 5.3 you were on your own. but thanks to Sara there's hope in sight: the new interface JsonSerializable. Classes implementing this interface have to provide a method jsonSerialize() which will be called by json_encode() and has to return a JSON-compatible representation of the data by doing whatever you want. So let's take a look:

<?php
class JsonTest implements JsonSerializable {
    private $a, $b;

    public function __construct($a, $b) {
        $this->a = $a;
        $this->b = $b;
    }

    public function jsonSerialize() {
        return $this->a + $this->b;
    }
}

echo json_encode(new JsonTest(23, 42));
?>

65

Now this example in itself is of course useless, but let's create a bigger structure, which includes a few of these objects:

<?php
$data = array(
    new stdClass();
    new JsonTest(1,2),
    new JsonTest(3,4),
    array(5,6)
);
echo json_encode($data);
?>

[{},3,7,[5,6]]

Of course you'd usually have more complex serialization logic, but that's left to you.

Now almost certainly somebody will ask "and what about the other way round?" - The only answer there is: Sorry there we can't do much. JSON doesn't encode and meta-information so our generic parser in json_decode() can't do anything special. But anyways: The new interface will certainly be useful.

At last a short disclaimer: PHP trunk is a development tree. Features in their may be changed at anytime and might not be released. Feedback is welcome.

Sun recently introduced their Amber Road storage systems which act like a storage appliance with a Web-Interface for configuration and analytics. Due to the power of DTrace combined with an AJAX web-inerface, you have the ability to really see what's going on. Brendan Gregg, the engineer who's famous for screaming at his storage systems, recently published a new blog posting giving some insights on the heat maps created by these systems. But Sun engineers won't be Sun engineers if they don't have weird ideas. So what about sending text messages to the analytics software? - Scroll to the bottom of Brendan's blog to see what I mean.