The source code

    /**
     * @class Ext.direct.JsonProvider
     * @extends Ext.direct.Provider
     */
    Ext.direct.JsonProvider = Ext.extend(Ext.direct.Provider, {
        parseResponse: function(xhr){
            if(!Ext.isEmpty(xhr.responseText)){
                if(typeof xhr.responseText == 'object'){
                    return xhr.responseText;
                }
                return Ext.decode(xhr.responseText);
            }
            return null;
        },

        getEvents: function(xhr){
            var data = null;
            try{
                data = this.parseResponse(xhr);
            }catch(e){
                var event = new Ext.Direct.ExceptionEvent({
                    data: e,
                    xhr: xhr,
                    code: Ext.Direct.exceptions.PARSE,
                    message: 'Error parsing json response: \n\n ' + data
                })
                return [event];
            }
            var events = [];
            if(Ext.isArray(data)){
                for(var i = 0, len = data.length; i < len; i++){
                    events.push(Ext.Direct.createEvent(data[i]));
                }
            }else{
                events.push(Ext.Direct.createEvent(data));
            }
            return events;
        }
    });