topic Re: Legend and SOAP method in ArcGIS API for Silverlight Questions

Legend and SOAP method

LanceCrumbliss — Thu, 27 May 2010 10:24:15 GMT

hi all,

i've been using the SOAP method to return legend images for a while now. i've noticed lately that on occasion, while the GetLegendInfo() method successfully executes on the server and returns to the client app the URL's pointing to the png files created on the server's arcgisoutput directory, that sometimes the png files are not actually created. fiddler of course will show a 404 error for each image attempted to be retrieved. it usually happens after the method has been called on the same service several times . maybe 20 or so over the course of 3 or 4 hours...i noticed this issue while debugging the app. of course, debugging hits the map service and makes the SOAP call. it will eventually right itself, but again, it may take several hours. restarting the map service, server, or reloading the client app doesn't resolve the issue. what would be the cause of this?

lance

Re: Legend and SOAP method

dotMorten_esri — Thu, 27 May 2010 15:20:12 GMT

I wouldn't recommend using SOAP to ArcGIS Server. The proxy generated is enourmous, and the overhead is even bigger (no caching at all). It just doesn't scale very well. Have you looked at this approach instead: http://resources.esri.com/arcgisserver/apis/silverlight/index.cfm?fa=codeGalleryDetails&scriptID=16800

Re: Legend and SOAP method

LanceCrumbliss — Fri, 28 May 2010 09:50:31 GMT

I wouldn't recommend using SOAP to ArcGIS Server. The proxy generated is enourmous, and the overhead is even bigger (no caching at all). It just doesn't scale very well. Have you looked at this approach instead: http://resources.esri.com/arcgisserver/apis/silverlight/index.cfm?fa=codeGalleryDetails&scriptID=16800

that is the approach i'm using. perhaps i worded it incorrectly in my original post. maybe i'm mixing terms here. GetLegendInfo() is a SOAP method and is being called on the web server, not the client, and the results (urls to the images) are sent back as a string to the client. what i meant was that sometimes the GetLegendInfo() method doesn't actually create the png files in the arcgisserver/arcgisoutput directory, but still returns a path to them.

hopefully that's correctly described now. any guess as to why the images are not generated sometimes?

lance

Re: Legend and SOAP method

nicogis — Fri, 28 May 2010 12:36:32 GMT

Have you checked in logs?

Re: Legend and SOAP method

LanceCrumbliss — Fri, 28 May 2010 12:50:33 GMT

Have you checked in logs?

Yep. no errors on verbose.

Re: Legend and SOAP method

nicogis — Fri, 28 May 2010 13:05:49 GMT

I have seen that from live it view ( http://silverlight.sharpgis.net/ArcGISLegend.html ) that are created image with prefix '_ags_'. Arcgis server clear this images after 10 minutes . you try see your settings cleaning mode

Re: Legend and SOAP method

LanceCrumbliss — Fri, 28 May 2010 14:00:39 GMT

I have seen that from live it view ( http://silverlight.sharpgis.net/ArcGISLegend.html ) that are created image with prefix '_ags_'. Arcgis server clear this images after 10 minutes . you try see your settings cleaning mode

hm, not sure where that specific setting is. but in the Server Manager, I can edit the arcgisserver/arcgisoutput directory to have a maximum file age of XX minutes, and it's currently set to 30 and the cleaning mode is set to "based on time elapsed since last accessed". are those the settings you're referring to?

Re: Legend and SOAP method

nicogis — Fri, 28 May 2010 14:50:03 GMT

<Cleaning>sliding</Cleaning>
<MaxFileAge>600</MaxFileAge>

for details see
http://help.arcgis.com/en/arcgisserver/10.0/help/arcgis_server_dotnet_help/index.html#//0093000000mq000000.htm

Re: Legend and SOAP method

LanceCrumbliss — Fri, 28 May 2010 15:53:32 GMT

<Cleaning>sliding</Cleaning>
<MaxFileAge>600</MaxFileAge>

for details see
http://help.arcgis.com/en/arcgisserver/10.0/help/arcgis_server_dotnet_help/index.html#//0093000000mq000000.htm

yeah, that's the same setting as in the Server Manager, and it's currently set to 30 minutes (1800 seconds in the .dat file), last accessed (sliding in the .dat file). i don't see how this could be the cause of my problem though.

Re: Legend and SOAP method

nicogis — Sun, 12 Dec 2021 07:51:37 GMT

I have seen the code of #gis.

I think that the problem is here:

Layer[] legend = null;
     if (context.Cache[soapUrl] != null)
      legend = context.Cache[soapUrl] as Layer[];
     if(legend == null)
     {
      legend = LegendGenerator.GetLegend(soapUrl);
      context.Cache.Insert(soapUrl, legend, null, System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(15), System.Web.Caching.CacheItemPriority.AboveNormal, null);
     }
     if (isJson)
     {
      GenerateJson(context, legend, isPrettyJson);
     }

If cache is used until 15 minutes, it uses legend in cache without regenerate legend image. So your 10 minutes can have an interval of 5 minutes without images because they are clean from server! In code should be set value <=MaxFileAge .

Re: Legend and SOAP method

LanceCrumbliss — Wed, 02 Jun 2010 11:46:37 GMT

hm, setting the cache in code to 9 minutes and the arcgisoutputdirectory MaxFileAge to 10 minutes didn't resolve the issue either.

Re: Legend and SOAP method

LanceCrumbliss — Thu, 03 Jun 2010 10:11:27 GMT

i'm wondering if anyone from ESRI has a suggestion as well? this is a bit of a show-stopper at the moment.

Re: Legend and SOAP method

nicogis — Thu, 03 Jun 2010 11:36:53 GMT

The problem that I say you however there is (cache).

I advise you do debug or set message (in source code) in log so you can understand where is the problem. I don't know how help you.

Re: Legend and SOAP method

dotMorten_esri — Thu, 03 Jun 2010 13:52:12 GMT

What happens if you disable caching in the REST endpoint? Or have the rest endpoint do caching of the images instead of just the URL to the images?

Re: Legend and SOAP method

LanceCrumbliss — Thu, 03 Jun 2010 17:13:42 GMT

What happens if you disable caching in the REST endpoint? Or have the rest endpoint do caching of the images instead of just the URL to the images?

i will try both of those. trying the first suggestion now. of course, with every hit to the page, a new set of legend images are added to the arcgisoutput directory (to be expected when not caching). i'll see how it behaves over time and then try the second approach.

Re: Legend and SOAP method

RyanCoodey — Wed, 30 Jun 2010 16:48:32 GMT

I just implemented this legend control (It's great, thanks a lot SharpGIS)... but I am having the EXACT same problem!

-After 10 minutes (the MaxFileAge) the legend images go away, this is expected, but why doesn't the Legend.ashx trigger these to be re-created after they have been cleaned out?
- As ciava.at mentioned, I see the Legend.ashx does something with caches at 15 min, but I am not sure what? Sorry, not real familiar with SOAP...
- It is some random time after the images have been cleaned out until Legend.ashx will then trigger them to be re-created (one time it was about 20 min, once an hour)... not sure what triggers it.

What happens if you disable caching in the REST endpoint?

What do you mean by this? The ArcGIS Server service is not caching. The REST API cache is set to be cleared daily at 1:00 am. Are you saying to disable caching (aka cleaning) on the arcgisoutput directory? I see how this would work, but I ideally don't want to disable this for all the other services that are running just to fix this problem... I am fine with it for the legend images, but preferably not everything else. Maybe I can set the time up to like an hour.

Or have the rest endpoint do caching of the images instead of just the URL to the images

I see what you are saying here, but not sure how to do this, could you please elaborate a bit more?

Thanks a lot for any help!

Re: Legend and SOAP method

dotMorten_esri — Thu, 01 Jul 2010 15:47:14 GMT

What do you mean by this?

I was referring to the custom rest endpoint in the sample. It's doing caching for the 10 mins, but you could just pull that code out of the sample.

Re: Legend and SOAP method

RyanCoodey — Thu, 01 Jul 2010 21:14:34 GMT

I was referring to the custom rest endpoint in the sample. It's doing caching for the 10 mins, but you could just pull that code out of the sample.

Oh, gotcha, thanks! That did the trick!

This got me tinkering with your code a bit and learning about System.Web.Caching.Cache and from what I can tell, it was the fact that it is using a "Sliding Expiration" that it had this problem... I set it to use an "Absolute Expiration" (of 5 min just to make sure) and I think that should still allow some caching (for excessive hits) but not have this problem.

Thanks a lot!

Re: Legend and SOAP method

dotMorten_esri — Thu, 01 Jul 2010 22:36:35 GMT

Oops! Good find

Re: Legend and SOAP method

PANKAJBOBADE — Tue, 06 Sep 2011 06:03:10 GMT

Hi There,
I am completely new to ArcGIS Java Script APIs and currently facing problem to display symbology / legend. i have downloaded the TOC sample from net & its shows Layer names properly in tree control [just like arcmap] without symbology. When checked author told that componety either expects ArcGIS 10 or application server to be in public domain.
Currenl;y i am working on ArcGIS 9.3.1 with REST APIs.

Any body can help on this related to sample if any available using getLegendInfo & java script.

Thanks in advance.