I'm trying to get a jsTree working with on demand loading of subnodes. My code is this:

```

jQuery('#introspection_tree').jstree({ 
        "json_data" : {
            "ajax" : {
                url : "http://localhost/introspection/introspection/product"
            }
    },
    "plugins" : [ "themes", "json_data", "ui" ]
    });

```

The json returned from the call is

```

[
  {
    "data": "Kit 1",
    "attr": {
      "id": "1"
    },
    "children": [
      [
        {
          "data": "Hardware",
          "attr": {
            "id": "2"
          },
          "children": [

          ]
        }
      ],
      [
        {
          "data": "Software",
          "attr": {
            "id": "3"
          },
          "children": [

          ]
        }
      ]
    ]
  }
  .....
]

```

Each element could have a lot of children, the tree is going to be big. Currently this is loading the whole tree at once, which could take some time. What do I have to do to implement on-demand-loading of child-nodes when they are opened by the user?

Thanks in advance.