I'm trying to create a data store that will load the data schema and records on fly. Here is the current code i have and I'm not sure how to setup the array reader properly since i don't have the schema before query returns.

 ds = new Ext.data.Store({
            url: 'http://10.10.97.83/cgi-bin/cgiip.exe/WService=wsdev/majax/jsbrdgx.p',
            baseParams: {
                cr: Ext.util.JSON.encode(omgtobxParms)
            },
            reader: new Ext.data.ArrayReader({
                //root:data.value.records
            }, col_names)
    });

{"name": "tmp_buy_book", 
 "schema": [
    { "name": "a", "type": "C"},
    { "name": "b", "type": "C"}
 "records": [["1", ""],
             ["1",""]]}