HttpService with JSON from server - help please

Question

Hi!
I am trying to pass back a JSON object to flex using
HttpService. The scenario is like this - using HttpService I am
calling an action since i am using Struts 2.0 . This action is
supposed to return a string in JSON format. When i am passing back
the data in XML format the data is properly displayed with the
required hierarchail structure. But when I am passing back the JSON
string it is not displaying anything.
This is the call to server
<mx:HTTPService id="srv" url="...... /
myaction/getSomeData.action"/>
the srv value is coming as null.
I am a total newbie to flex.
Thanks for any help in advance,
Rohit

Answer 1

The code is as follows:
<?xml version="1.0"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml"
xmlns:ilog="
http://www.ilog.com/2007/ilog/flex"
layout="absolute" creationComplete="srv.send()">
<mx:HTTPService id="srv" url="
http://192.168.103.128:8081/ManageMe/manageme/generateXMLForGantt.action"/>
<mx:Style>
GanttSheet
borderStyle:none;
rowPadding: 4;
TaskItemRenderer {
borderColor: "0x388F24";
backgroundColor: "0xB5D021";
rollOverColor: "0xFDF621";
borderRollOverColor: "0xF4C811";
selectedColor: "0xFDB201";
borderSelectedColor: "0xFF9201";
selectedRollOverColor: "0xFDF621";
borderSelectedRollOverColor: "0xF4C811";
textPosition: "right";
v-align: "top";
barTopMargin: 0.3;
barBottomMargin: 0.3;
.milestone {
startSymbolBorderColor: "0x24598a";
startSymbolColor: "0x4422EE";
.summary {
borderColor: "0x000000";
backgroundColor: "0x22ee56";
endSymbolBorderColor: "0x000000";
endSymbolColor: "0x000000";
startSymbolBorderColor: "0x000000";
startSymbolColor: "0x000000";
</mx:Style>
<mx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
import mx.collections.HierarchicalData;
[Bindable]
public var tasks:HierarchicalData = new
HierarchicalData(srv);
//[Bindable]
// public var tasks:HierarchicalData = null;
[Bindable]
public var constraints:ArrayCollection = new
ArrayCollection([
{ fromId:"T2", toId:"T3", kind:"endToStart" },
{ fromId:"T3", toId:"T4", kind:"endToStart" },
{ fromId:"T5", toId:"T6", kind:"endToStart" },
{ fromId:"T6", toId:"T7", kind:"endToStart" },
{ fromId:"T7", toId:"T8", kind:"endToStart" },
{ fromId:"T7", toId:"T8", kind:"endToStart" }
]]>
</mx:Script>
<mx:VBox width="100%" height="100%">
<mx:ApplicationControlBar id="toolBar" width="100%"
height="40">
<mx:HBox>
<mx:Button toolTip="Expand All Items" width="30"
height="28" click="myDataGrid.expandAll()"
icon="@Embed(source='../resources/expanded.png')"/>
<mx:Button toolTip="Collapse All Items" width="30"
height="28" click="myDataGrid.collapseAll();"
icon="@Embed(source='../resources/unhierarchical.png')"/>
<mx:Button toolTip="Zoom In" width="30" height="28"
icon="@Embed(source='../resources/zoom in5.png')"/>
<mx:Button toolTip="Zoom Out" width="30" height="28"
icon="@Embed(source='../resources/zoom out7.png')"/>
<!--<mx:Button toolTip="Expand Chart" width="30"
height="28" click="myGanttSheet.showAll(margin=10);"
icon="@Embed(source='../resources/zoom fit6.png')"/> -->
</mx:HBox>
</mx:ApplicationControlBar>
<ilog:TaskChart id="taskChart" width="100%" height="100%"
taskDataProvider="{srv.lastResult}"
taskItemStyleName="TaskItemRenderer" >
<ilog:dataGrid>
<ilog:GanttDataGrid id="myDataGrid" rowHeight="24">
<ilog:columns>
<mx:AdvancedDataGridColumn dataField="id"
headerText="ID"/>
<mx:AdvancedDataGridColumn dataField="name"
headerText="NAME"/>
<mx:AdvancedDataGridColumn dataField="baselineStart"
headerText="START TIME"/>
<mx:AdvancedDataGridColumn dataField="baselineEnd"
headerText="END TIME"/>
</ilog:columns>
</ilog:GanttDataGrid>
</ilog:dataGrid>
<ilog:ganttSheet>
<ilog:GanttSheet id="myGanttSheet"
taskItemRenderer="TaskChartCustomTaskItemRenderer"
moveEnabled="false" resizeEnabled="false"/>
</ilog:ganttSheet>
</ilog:TaskChart>
</mx:VBox>
</mx:Application>