Passing values from Java script API to GP Service and reading it in custom GP Tool

Discussion created by cyrilcherian on Feb 4, 2013
Not sure  this is to be posted in JavaScript API or Geoprocessing.

I have an ESRI Javascript application that uses a geoprocessing service that uses a cutsom GP tool.
Since I have a set of values to be passed to the GP service I am planning to pass in it as a record set instead of string values. These are just attributes and no geometry associated with it. I think I can use FeatureSet in Javascript to pass GP input parameters.

Something like this. Let me know if this is the right way to pass record sets. I will have several records.
var attr = {"OBJETID:1", "Name":"Test", "Address:"Value2"};
var graphic = new esri.Graphic(null,null,attr,null);
var features= [];
var featureSet = new esri.tasks.FeatureSet();
featureSet.features = features;

Now inside the custom GP function tool how do I set the paramaters to read the input? Following is what I am trying to do. Is this the correct approach?

IGPParameterEdit gpParameterEdit = new GPParameterClass();
            IGPDataType gpDataType = new GPRecordSetTypeClass();// GPStringTypeClass();
            IGPValue gpValue = new GPRecordSetClass();// GPStringClass(); ;
            gpParameterEdit.Name = "legal_desc";
            gpParameterEdit.DisplayName = "Legal Description";
            gpParameterEdit.DataType = gpDataType;
            gpParameterEdit.Value = gpValue;
            gpParameterEdit.Direction = esriGPParameterDirection.esriGPParameterDirectionInput;
            gpParameterEdit.ParameterType = esriGPParameterType.esriGPParameterTypeRequired;

Then while Casting the value, How do I cast and read the values from the input featureset? Following is what I am trying to do and it is returning null for gpRecordSet.
IGPValue gpValue = parameterValueArray.GetGPValue(_parameterIndex);
            IGPRecordSet gpRecordSet = (IGPRecordSet)gpValue;

Basically I am trying to see how to pass in set of attributes from JavaScript and read it in custom GP Tool.

Now the return value I expect in the JavaScript application is a polygon graphic and no attributes. What is the best way to return the polygon? What I understand from my research is that I need to create in-memory featurecalss and return the polygon as feature. Is there a better way.

All help appreciated.