geoserver - How to send WPS request using OpenLayers

I have generated the WPS request below using GeoServer's WPS Request Builder. I wish to append more parameters to this request (geometry selection), and then send it either using GET or POST from within my OpenLayers JavaScript code. I can't seem to get information on how this can be done. How can I append geometry selection parameter to the request, and how can I send the request using OpenLayers? Any assistance will highly appreciated.

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      features
      
        

          
            
          
        
      
    
    
      aggregationAttribute
      
        pop

      
    
    
      function
      
        Sum
      
    
    
      singlePass

      
        Yes
      
    
  
  
    
      result
    
  

My environment: GeoServer 2.1.3, OpenLayers 2.11, PostGIS 1.5.

Answer

Incorporate filters within the section in a . The format of the filter is dependent on its type. More info on filters and examples is available here and here.

As for requests, I used OpenLayers' POST method to send request, as illustrated below:

var request = new OpenLayers.Request.POST({
        url: WPS_HOST,
        data: wpsRequestData,
        headers: {

            "Content-Type": "text/xml;charset=utf-8"
        },
        callback: function (response) {
            //read the response from GeoServer
            var gmlParser = new OpenLayers.Format.GML();
            var xmlSum = gmlParser.read(response.responseText);
            // TODO: More operations here
        },
        failure: function (response) {
            alert("Something went wrong in the request");

        }
    });

I hope this will be of help to someone.