[geotk] NullPointerException with WFSFeatureStore

[Martin Desruisseaux]

Hello Emmanuel

I just had a look in the code. I saw a hard-coded timeout of 10 seconds
in the WebFeatureClient class (line 154 and 158). Would it be possible
that the server queried by your application take more than 10 seconds to
answer?

Hello Johann

I case of timeout, the WebFeatureClient.getCapabilities() method at line
159 logs a warning and returns null. However the Javadoc does not said
that this method may return null, and indeed the
WFSFeatureStore.checkTypeExists() method at line 114 does not verify if
the WFSCapabilities object is null, which causes the
NullPointerException. What would be the appropriate behaviour?

  * In case of failure, let WebFeatureClient throws an exception? (my
    preferred choice, since otherwise we get a NullPointerException
    anyway, which is much less informative).
  * In case of failure, have WebFeatureClient to return an empty
    WFSCapabilities? (I don't think it would be safe, since the caller
    does not know that there is a problem).
  * Document that WebFeatureClient.getCapabilities() may return null in
    case of failure, and revisit all caller code for making them null-safe?


    Martin



Le 09/12/14 07:18, Emmanuel Blondel a écrit :
> Hello,
>
> I'm currently assessing the WFS client from Geotoolkit. We would like
> to use it in a new project (also because we would like to use Apache
> SIS progressively), with the purpose to discover featuretypes and
> fetch the featureCollection data, relying on the official GeoAPI.
>
> I've been trying to use Geotoolkit 4.0-M2 (which AFAIK is the latest
> milestone release), and the geotk-wfs-client.
>
> I get the following stack trace :
>
> /déc. 08, 2014 11:11:58 PM org.geotoolkit.data.wfs.WebFeatureClient
> getCapabilities//
> //AVERTISSEMENT: TimeOut error, the server takes too much time to
> answer. //
> //Exception in thread "main" java.lang.NullPointerException//
> //    at
> org.geotoolkit.data.wfs.WFSFeatureStore.checkTypeExist(WFSFeatureStore.java:114)//
> //    at
> org.geotoolkit.data.wfs.WFSFeatureStore.<init>(WFSFeatureStore.java:107)//
> //    at org.fao.fi.wfstesting.App.main(App.java:33)/
>
>
> for this code:
>
>         final WebFeatureClient wfsServer = new WebFeatureClient(new
> URL("http://www.fao.org/figis/geoserver/ows"), "1.1.0");
>         final GetCapabilitiesRequest getCapa =
> wfsServer.createGetCapabilities();
>        
>         final GetFeatureRequest getFeature = wfsServer.createGetFeature();
>         //simplify WFS like a datastore
>         final FeatureStore store = new WFSFeatureStore(wfsServer);
>        
>         String[] typeNames = store.getTypeNames();
>         for(String typeName : typeNames){
>             FeatureType ft = store.getFeatureType(typeName);
>             System.out.println(ft.getName());
>             System.out.println("==");
>         }
>
> I admit i'm lost. I had a look to the code for which i identified the
> timeout warning.
> But nothing about the exception. Any idea?
>
> Thanks in advance for your help
> Emmanuel

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