Zum Daten-Austausch bevorzuge ich JSON ...
Es ist selbst in formatierter Form um die Hälfte kleiner als ein XML-Dokument ... und ist vor allem typisiert. Und wie ich finde häufig auch lesbarer als XML.

Ein krasses Beispiel was ich die tage gesehen habe ... SOLR (Eine Java-Web-Anwendung zum füttern eines Lucene Such Indexes):

XML:
Code: 
<add>

<doc>
  <field name="id">F8V7067-APL-KIT</field>
  <field name="name">Belkin Mobile Power Cord for iPod w/ Dock</field>
  <field name="manu">Belkin</field>
  <field name="cat">electronics</field>
  <field name="cat">connector</field>
  <field name="features">car power adapter, white</field>
  <field name="weight">4</field>
  <field name="price">19.95</field>
  <field name="popularity">1</field>
  <field name="inStock">false</field>
  <!-- Buffalo store -->
  <field name="store">45.17614,-93.87341</field>
  <field name="manufacturedate_dt">2005-08-01T16:30:25Z</field>
</doc>

<doc>
  <field name="id">IW-02</field>
  <field name="name">iPod &amp; iPod Mini USB 2.0 Cable</field>
  <field name="manu">Belkin</field>
  <field name="cat">electronics</field>
  <field name="cat">connector</field>
  <field name="features">car power adapter for iPod, white</field>
  <field name="weight">2</field>
  <field name="price">11.50</field>
  <field name="popularity">1</field>
  <field name="inStock">false</field>
  <!-- San Francisco store -->
  <field name="store">37.7752,-122.4232</field>
  <field name="manufacturedate_dt">2006-02-14T23:55:59Z</field>
</doc>


</add>
JSON:
Code: 
[
  {
    "id" : "978-0641723445",
    "cat" : ["book","hardcover"],
    "name" : "The Lightning Thief",
    "author" : "Rick Riordan",
    "series_t" : "Percy Jackson and the Olympians",
    "sequence_i" : 1,
    "genre_s" : "fantasy",
    "inStock" : true,
    "price" : 12.50,
    "pages_i" : 384
  }
,
  {
    "id" : "978-1423103349",
    "cat" : ["book","paperback"],
    "name" : "The Sea of Monsters",
    "author" : "Rick Riordan",
    "series_t" : "Percy Jackson and the Olympians",
    "sequence_i" : 2,
    "genre_s" : "fantasy",
    "inStock" : true,
    "price" : 6.49,
    "pages_i" : 304
  }
,
  {
    "id" : "978-1857995879",
    "cat" : ["book","paperback"],
    "name" : "Sophie's World : The Greek Philosophers",
    "author" : "Jostein Gaarder",
    "sequence_i" : 1,
    "genre_s" : "fantasy",
    "inStock" : true,
    "price" : 3.07,
    "pages_i" : 64
  }
,
  {
    "id" : "978-1933988177",
    "cat" : ["book","paperback"],
    "name" : "Lucene in Action, Second Edition",
    "author" : "Michael McCandless",
    "sequence_i" : 1,
    "genre_s" : "IT",
    "inStock" : true,
    "price" : 30.50,
    "pages_i" : 475
  }
]