XML or JSON reponse for Flex applications with PHP backend? - php

Question

I'm developing a floorplanner Flex mini application. I was just wondering whether JSON or XML would be a better choice in terms of performance when generating responses from PHP. I'm currently leaning for JSON since the responses could also be reused for Javascript. I've read elsewhere that JSON takes longer to parse than XML, is that true? What about flexibility for handling data with XML vs JSON in Flex?

Answer 1

I'd go with JSON. We've added native JSON support to Flash Player, so it will be as fast on the parsing side as XML and it's much less verbose/smaller.
=Ryan ryan#adobe.com

Answer 2

JSON is not a native structure to Flex (strange, huh? You'd think that the {} objects could be easily serialized, but not really), XML is. This means that XML is done behind the scenes by the virtual machine while the JSON Strings are parsed and turned into objects through String manipulation (even if you're using AS3CoreLib)... gross... Personally, I've also seen inconsistencies in JSONEncoder (at one point Arrays were just numerically indexed objects).
Once the data has been translated into an AS3 object, it is still faster to search and parse data in XML than it is with Objects. XPath expressions make data traversal a pleasure (almost easy enough to make you smile compared to other things out there).
On the other hand JS is much better at parsing JSON. MUCH, MUCH BETTER. But, since the move to JavaScript is a "maybe... someday..." then you may want to consider, "will future use of JSON be worth the performance hit right now?"
But here is a question, why not simply have two outputs? Since both JS and AS can provide you POSTs with a virtually arbitrary number of variables, you really only need to concern yourself with how the server send the data not receives it. Here's a potential way to handle this:
// as you are about to output:
$type = './outputs/' . $_GET[ 'type' ] . '.php';
if( file_exists( $type ) && strpos( $type, '.', 1 ) === FALSE )
{
include( $type );
echo output_data( $data );
}
else
{
// add a 404 if you like
die();
}
Then, when getting a $_GET['type'] == 'js', js.php would be:
function output_data( $data ){ return json_encode( $data ); }
When getting $_GET['type'] == 'xml', xml.php would hold something which had output_data return a string which represented XML (plenty of examples here)
Of course, if you're using a framework, then you could just do something like this with a view instead (my suggestion boils down to "you should have two different views and use MVC").

Answer 3

No, JSON is ALWAYS smaller than XML when their structures are completely same. And the cost of parsing text is almost up to the size of the target text.
So, JSON is faster than XML and if you have a plan to reuse them on javascript side, choose JSON.
Benchmark JSON vs XML:
http://www.navioo.com/ajax/ajax_json_xml_Benchmarking.php

Answer 4

If you're ever going to use Javascript with it, definitely go with JSON. Both have a very nice structure.
It depends on how well Flex can parse JSON though, so I would look into that. How much data are you going to be passing back? Error/Success messages? User Profiles? What kind of data is this going to contain?
Is it going to need attributes on the tags? Or just a "structure". If it needs attributes and things like that, and you don't want to go too deep into an "array like" structure, go with XML.
If you're just going to have key => value, even multi-dimensional... go with JSON.
All depends on what kind of data you're going to be passing back and forth. That will make your decision for you :)

Answer 5

Download time:
JSON is faster.
Javascript Parse
JSON is faster
Actionscript Parse
XML is faster.
Advanced use within Actionscript
XML is better with all the E4X functionality.
JSON is limited with no knowledge of Vectors meaning you are limited to Arrays or will need to override the JSON Encoder in ascorelib with something such as
else if ( value is Vector.<*> ) {
// converts the vector to an array and
return arrayToString( vectorToArray( value ) );
} else if ( value is Object && value != null ) {
private function vectorToArray(__vector:Object):Array {
var __return : Array;
var __vList : Vector.<*>;
__return = new Array;
if ( !__vector || !(__vector is Vector.<*>) )
{
return __return;
}
for each ( var __obj:* in (__vector as Vector.<*>) )
{
__return.push(__obj);
}
return __return;
}
But I am afraid getting those values back into Vectors is not as nice. I had to make a whole utility class devoted to it.
So which one is all depending on how advanced your objects you are going to be moving.. More advanced, go with XML to make it easier ActionScript side.
Simple stuff go JSON