Intermittent JSON error in workflow

Permanently deleted user

October 19, 2012 20:34

Hello all,

I am running Essentials 3.10.1 with Silverlightviewer 1.6.  I have made a few parcel query workflows based on the sample 'SearchParcelsID' workflow.  They now look for parcel attributes such as SBL, owner name and address.  They seem to work fine during the debug testing process.  I put them in my Silverlight site and they work fine but I get the occasional following error pop up:

"Exception has been thrown by the target of an invocation.  Workflow 'ParcelAddressSearch' failed.  Aborted Exception: 'Error processing task results.'.  JSON string is invalid or not supported.  Value does not fall within the expected value."

Considering that I can get this workflow to work 3 times in a row but then have it fail seems rather odd.  Any suggestions?

You can try to see the behavior by hitting the following site:  http://gis2.erie.gov/GC/ErieCountyNY

I have used Fiddler2 to check out the point at which it fails but it just shows me the error I typed above. 

Thanks

Mike G

Erie County NY, Office of GIS

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  Permanently deleted user

  October 19, 2012 20:43

  Hello all,

  After playing with the application a few minutes it looks like the workflows don't like it when you do the same query a second time with the first query still in the search history.  Once it is deleted (manually at this point) from the search history, the workflow works fine.  Does anyone know how to see if the query exists in history?

  I name the collection 'Search by Address: 95 Franklin St' during the query for that address.  Can I remove all collections named that before the query is run?

  Thanks

  Mike G

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  Permanently deleted user

  October 19, 2012 22:45

  This is a known issue with the communication between the ESRI WPF API and the ArcGIS Server 10.1 Web Adaptor. The WPF API includes caching information in the headers of web requests from Query tasks and the like that is not understood by the Web Adaptor, so it returns an error message in the form of an HTML page. Since this is not a JSON response, you get the error that you are seeing.

  This typically happens on every second run, especially when testing, as the caching information appears to be attached to every second request for the same result set. Since you typically search for the same things over and over again when testing, the error can actually be much more apparent here than in production, but this issue will affect every workflow that talks to ArcGIS Server after an upgrade to ArcGIS Server 10.1.

  The best solution at the moment is to talk to ArcGIS Server directly from Workflow, rather than going through the Web Adaptor. Usually this just entails putting :6080 after the server name, so that the message goes to this port instead of the default port 80. 

  So for example, the REST endpoint:

  http://myserver/arcgis/rest/services

  Will become:

  http://myserver:6080/arcgis/rest/services 

  In the 3.11 release of Essentials an option to disable client caching on ESRI Tasks is planned, which will also work around this issue until it can be fixed.

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  Permanently deleted user

  October 24, 2012 05:05

  Was looking for a solution for this. Thanks.

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  Permanently deleted user

  November 21, 2012 23:30

  Where is this option to disable client caching of ESRI tasks? 

  Since our ArcGIS Server is behind a firewall (we use a Web Adaptor on a proxy machine), connecting directly to ArcGIS Server is not possible.

   

  EDIT

  Nevermind, I found it. It was the first In Argument property of the query task /customer/servlet/servlet.FileDownload?file=00P6000000e88HjEAI

  This fixed the problem for me!

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