SOE REST Service - Is it possible to send the http status code from the operation

Question

Hi Folks,

I was wondering if it is possible to send the status code to the client from the SOE operation. I know we can set the Content-Type header and also the ResponseDataType on the "responseProperties". Does the "responseProperties" takes other parameters as well such as http status code?

RahulRavikumar · Answer

What errors are you getting when you return null?

When you set custom HTTP headers, you have to handle them by looking for custom HTTP headers yourself from the client code.

If you want the application to return an error message, then it should be HTTP status 500 (internal server error | error processing request). All you need to do for that, is to throw an Exception with a message, and the REST handler will intercept the exception and treat it as a 500.

So, 
private byte[] GetImage(System.Collections.Specialized.NameValueCollection boundVariables, 
            ESRI.ArcGIS.SOESupport.JsonObject operationInput, 
            string outputFormat, 
            string requestProperties, 
            out string responseProperties)
        {
           try {
              ........
           }catch(Exception e) {
             //Log your exception and throw it so that the REST handler intercepts your exception
            // and treats it as a HTTP 500.
             throw e;
          }
        }

PrashantKhanal · Answer

If your SOE is in .NET you will have to construct the jsonified string yourself.

Essentially it would be:

responseProperties = "{
  \"Content-Type\" : \"image/png\",
  \"X-HTTP-Status\" : \"500 - An error occurred while generating the image.\"
}";

Thanks Rahul.
X-HTTP-Status is not a standard header to my understanding. It should be an experimental header and do you mean the client should be able to interpret this header?

I tried to create a sample operation that constructs the response properties in the way you suggested but somehow I am not able to make it work. 
RestOperation findNearFeatsOp = new RestOperation("GetImage",
                                                      new string[0] ,
                                                      new string[] { "img" },
                                                      GetImage);
..................

private byte[] GetImage(System.Collections.Specialized.NameValueCollection boundVariables, 
            ESRI.ArcGIS.SOESupport.JsonObject operationInput, 
            string outputFormat, 
            string requestProperties, 
            out string responseProperties)
        {
            responseProperties = "{\"Content-Type\" : \"image/png\",\"X-HTTP-Status\" : \"404 - Could not find the image requested.\"}";

return null;
        }

Once error is encountered, I add X-HTTP-Status header and return null. I returned because I have nothing to return to the client. I guess that particular return null statement is causing the problem. I am confused what to return in such case. In case of json error, we just wrap the error in json and send the json string as bytes.

RahulRavikumar · Answer

If your SOE is in .NET you will have to construct the jsonified string yourself.

Essentially it would be:

responseProperties = "{
  \"Content-Type\" : \"image/png\",
  \"X-HTTP-Status\" : \"500 - An error occurred while generating the image.\"
}";