Interpreting firebug results on feature layers in the net tab

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03-21-2013 10:38 AM
MikeOnzay
Occasional Contributor III
I need help in interpreting what I am seeing and wondering why I'm seeing duplicate features.

I'm using this example: http://help.arcgis.com/en/webapi/javascript/arcgis/jssamples/fl_layer_definition.html "Feature layer with layer definition applied" on my own server and viewing the results after opening the page in Firefox. I modified the tooltip code so I can see the OBJECTID. Your results may be different from what I describe here. I used the tooltip to find the OBJECTID on screen and then expanded the URLs to find the same OBJECTID. I'm specifically looking at the shaded area next to the I-35 sign on the map.

When I expand the keys under the URLs in the JSON tab on the NET tab I can see where the featurelayer (fields) is being created (the line starts as GET1?). Then there are 3 more lines that when expanded have a key called "features". The first one has 1 feature (0), the second line has 4 features (0,1,2,3) and the third line has 2 features (0,1).

In the second line with 4 features, the 4th feature has an OBJECTID of 5095 and in the third line the 2nd feature has an OBJECTID of 5095. Does that mean that this feature is being downloaded twice? I'm not moving the map around at all.

There are also URLs that when expanded do not show any features. They appear to show the same keys as the ones I described above but the features key cannot be expanded. These have a size of 2.6kb. I'm not sure what is happening here.

In this example the sizes that are being downloaded are not a big deal. In my own data I have some large features and when I run this example against my own internal data and limit the definition expression to one feature I get six URLs returned. I'm assuming the first two are about the creation of the actual feature layer. The next four seem to be pairs of duplicates. The URLs with a size of 865B have a key called features that appears to be empty. The URLs with a size of 4.2KB have a key called features that is listing the feature I defined.

So, I asked myself if in fact it was downloading the feature twice. Am I interpreting these results correctly?

[ATTACH=CONFIG]22845[/ATTACH]
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KellyHutchins
Esri Frequent Contributor
Take a look at the 'Vector Tiling' section of this help topic for details on the behavior you are seeing:

http://developers.arcgis.com/en/javascript/jshelp/best_practices_feature_layers.html
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