Using OpenLayers 2 WPS client?

Question

I am using OpenLayers API in my web application and trying to interact with the local GeoServer via WPS. The problem I am facing is that, WPS client.execute() works only in case, if the output of the Process is Geometry type (i.e. forJTS:intersection,JTS:buffer, etc). It does not seem to work if the output is double/string/bool(i.e. forJTS:area,JTS:envelope,JTS:equalsExact, etc).

For e.g., the following code does not popup a "success" message.

 var geometry = OpenLayers.Geometry.fromWKT(
                   'POLYGON((110 20,120 20,120 10,110 10,110 20))'
                );

 client.execute({
            server: "local",
            //process: "JTS:envelope",
            process: "JTS:geometryType",
            inputs: {
                geom: geometry
            },          
            success: function(output) {
                alert('success');
            }
  });

But if I happen to replace JTS:geometryType with JTS:envelope, it works !!..

Not much of tutorials are available on internet. Is it a restriction in client.execute() or am I doing something wrong in the code ?

Answer 1

I haven't found the right answer to this problem, until now... but anyway, for others facing similar problem, here is a workaround solution.

testWPS is my WPS process whose input is string and output is string

OpenLayers.Request.POST({
        url: "http://localhost:8080/geoserver/wps,
        params: {
            "SERVICE": "WPS",
            "REQUEST": "Execute",
            "VERSION": '1.0.0',
            "IDENTIFIER": 'gs:testWPS',
            "RawDataOutput": 'result',
            "datainputs": "name=this now works with string,double,bool as output"
        },
        success: function(response) {
                     //Do something on success
        },
        failure: function(res){     
                     alert('failure');
        }

    });

Answer 2

I think that the OpenLayers WPS client is not up to scratch.

Trying it myself with this code

<script src="http://localhost:8080/geoserver/www/OpenLayers-2.13.1/OpenLayers.debug.js"></script>

    client = new OpenLayers.WPSClient({
        servers: {
            wps_test: 'http://localhost:8080/geoserver/wps/'
        }
    });
    gs_count = client.getProcess('wps_test', 'gs:Count')
    gs_count.execute({
      inputs:{
        features : points,
      },
      success : function(outputs){
        alert(outputs.result);
      }
    });

I get "TypeError: output.complexOutput is undefined" in OpenLayer.debug.js line 65467

mimeType: this.findMimeType(output.complexOutput.supported.formats, options.supportedFormats)

i.e. it appears to expect there to be a complex data output and not be able to cope with a literal data output.

and after more investigation I found this comment

/**
 * Class: OpenLayers.WPSProcess
 * Representation of a WPS process. Usually instances of
 * <OpenLayers.WPSProcess> are created by calling 'getProcess' on an
 * <OpenLayers.WPSClient> instance.
 *
 * Currently <OpenLayers.WPSProcess> supports processes that have geometries
 * or features as output, using WKT or GeoJSON as output format. It also
 * supports chaining of processes by using the <output> method to create a
 * handle that is used as process input instead of a static value.
 */

Update...

You can use PyWPS. This has a web client, example here... http://pywps.wald.intevation.org/documentation/course/client/index.html#

This handles literal data output.