topic Re: FeatureLayer ProxyUrl bug? in ArcGIS API for Silverlight Questions

FeatureLayer ProxyUrl bug?

BrooksShannon — Fri, 25 Jun 2010 19:07:22 GMT

Hey guys,

I'm attempting to use a FeatureLayer with a proxy, and I'm having some problems. Currently, I'm using the 2.0 public beta API, and I think the issues I'm seeing might be related to a bug, or bugs, in the API code.

If I specify that a FeatureLayer should use a proxy, like this:

<esri:FeatureLayer ID="MyFeatureLayer" 
                DisableClientCaching="True"
                Url="http://localhost/ArcGIS/rest/services/MyMapService/FeatureServer/0"
                ProxyUrl="http://localhost/MySLApp/proxy.ashx"
                Mode="OnDemand" 
                AutoSave="False"
                Color="Blue"
                OnDemandCacheSize="500"                 
                OutFields="NAME,IDENTIFIER,DLVRY_ADD"
                InitializationFailed="Layer_InitializationFailed"
                Initialized="Layer_Initialized">

I will receive the following exception, that I can capture in the layer's InitializationFailed event:

System.Net.WebException: The remote server returned an error: NotFound. ---> 
 System.Net.WebException: The remote server returned an error: NotFound.
 at System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
 at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
 at System.Net.Browser.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState)
 --- End of inner exception stack trace ---
 at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
 at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
 at System.Net.WebClient.GetWebResponse(WebRequest request, IAsyncResult result)
 at System.Net.WebClient.DownloadBitsResponseCallback(IAsyncResult result)

I spent a little time poking around with Firebug, and found out the following:

1) Things like tiled layers request the proxy page at

http://localhost/MySLApp/proxy.ashx?<theUrlItWants>

The FeatureLayer, however, requests the proxy page at

http://localhost/MySLApp/proxy.ashx<theUrlItWants>

during initialization - the key difference being the missing "?".

2) Post-initialization, the FeatureLayer goes back to requesting the proxy page at

http://localhost/MySLApp/proxy.ashx?<theUrlItWants>

The "?" is there where it should be - this time.

3) The FeatureLayer, unlike other map services, won't let me use a relative path to the proxy page. If I try using a relative path (say, "../proxy.ashx") I receive an exception claiming the URI kind can't be determined. I'm forced to specify an absolute path, along with the protocol.

It could very well be the case that this is resolved in the 2.0 RC API - but the download link appears broken, so I can't find out. As it stands right now, however, I can't think of any way to make this work. I could do something like use a proxy URL of

http://localhost/MySLApp/proxy.ashx?

(adding the "?" to the end) - but that makes any of the requests that come after layer initialization bomb. (Which is what led me to believe that it's probably just a bug in the FeatureLayer's initialization - or something that occurs internally near the time of initialization, anyways.)

Does anyone from ESRI have any information that could help in this situation?

Thanks!
Brooks

Re: FeatureLayer ProxyUrl bug?

DavidAllen-Williams — Mon, 28 Jun 2010 03:09:50 GMT

I'm getting the same problems with the 2.0RC, so it looks like this hasn't been resolved yet..

Re: FeatureLayer ProxyUrl bug?

BrooksShannon — Mon, 28 Jun 2010 14:48:16 GMT

I'm getting the same problems with the 2.0RC, so it looks like this hasn't been resolved yet..

Thanks for letting me know. Does anyone from ESRI know if this will be addressed at the 2.0 release?

Re: FeatureLayer ProxyUrl bug?

dotMorten_esri — Mon, 28 Jun 2010 23:43:46 GMT

Thanks. This will be addressed in final

Re: FeatureLayer ProxyUrl bug?

BrooksShannon — Tue, 29 Jun 2010 14:28:17 GMT

Thanks. This will be addressed in final

Thanks! I appreciate you letting me know.

FeatureLayer Url bug - can not use relative path

DavidAllen-Williams — Sat, 11 Dec 2021 12:12:52 GMT

Related to this issue, the 2.0RC also does not let you use a relative url for a feature layer - for example all the following fail with
[INDENT]System.UriFormatException: Invalid URI: The format of the URI could not be determined.

<esri:FeatureLayer Url="../mapit/dbo.MyFeature" ... />
<esri:FeatureLayer Url="~/mapit/dbo.MyFeature" ... />
<esri:FeatureLayer Url="/mapit/dbo.MyFeature" ... />
<esri:FeatureLayer Url="mapit/dbo.MyFeature" ... />

[/INDENT]

Hopefully will be fixed in final too?

Re: FeatureLayer ProxyUrl bug?

dotMorten_esri — Mon, 05 Jul 2010 14:57:13 GMT

All layer types requires an absolute URL to the service endpoint.

Re: FeatureLayer ProxyUrl bug?

JayOckers — Thu, 08 Jul 2010 18:38:21 GMT

Is there any word on when final release will drop?

Re: FeatureLayer ProxyUrl bug?

JayOckers — Mon, 12 Jul 2010 20:33:11 GMT

This is broken in a different way with the final release. When no proxy is used, the request looks like this:

http://HOSTNAME/ArcGIS/rest/services/MyMapService/MapServer/5/query?...

But when a proxy is used, the request looks like this:
https://HOSTNAME/ArcGIS/rest/services/MySecureMapService/MapServer/5?...

Re: FeatureLayer ProxyUrl bug?

RexHansen — Mon, 12 Jul 2010 22:58:17 GMT

During initialization a FeatureLayer will send two requests. One for metadata and another to query and return features.   If using a proxy and defining the ProxyUrl property, both requests will be redirected through the proxy.   There are two issues I discovered with the proxy page download included with the SDK:

1) The proxy.config file is not found when located outside the root folder. To fix, adjust the following method:

    public static string GetFilename(HttpContext context)
    {
        return context.Server.MapPath("proxy.config");
    }

2) If not token secured, the proxy always checks for Windows\HTTP authentication, which results in a duplication of requests.

Both items have been fixed in the SDK download from this page: http://help.arcgis.com/en/webapi/silverlight/help?Secure_services.htm

Re: FeatureLayer ProxyUrl bug?

JayOckers — Sat, 11 Dec 2021 12:12:55 GMT

During initialization a FeatureLayer will send two requests. One for metadata and another to query and return features. If using a proxy and defining the ProxyUrl property, both requests will be redirected through the proxy.

The issue I found is that the second request (the query) isn't formatted correctly when using a ProxyUrl. It's missing the word query and only returns metadata.

Workaround for this was to modify the proxy to detect this type of bad request and inject the proper syntax.

We added this right after the token is appended to the localUri:

Regex regex = new Regex(@"MapServer/\d+(\?)returnGeometry", RegexOptions.Compiled);
if (regex.IsMatch(localUri))
{
     localUri = regex.Replace(localUri, (m) =>
          {
               string newVal = m.Groups[0].Value.Replace("?", "/query?");
               return newVal;
          }
     );
}

Re: FeatureLayer ProxyUrl bug?

JayOckers — Tue, 13 Jul 2010 18:39:50 GMT

I'm having a similar problem using the identify task.

This is how the query should be formed:

MapServer/identify?geometryType=esriGeometryPoint&geometry={"x":959569.778050866,"y":3225324.48586893,"spatialReference":{"wkid":26715}}&returnGeometry=true&imageDisplay=1226,798,96&layers=visible&tolerance=2&mapExtent=954964.111157632,3221058.95804765,966234.665271614,3228394.93046442&f=json

But this is how it is being formed:

MapServer?geometryType=esriGeometryPoint&geometry={"x":959569.778050866,"y":3225324.48586893,"spatialReference":{"wkid":26715}}&returnGeometry=true&imageDisplay=1226,798,96&layers=visible&tolerance=2&mapExtent=954964.111157632,3221058.95804765,966234.665271614,3228394.93046442&f=json