topic Re: KmlLayer with a schema? in ArcGIS API for Silverlight Questions

KmlLayer with a schema?

ZachPride — Wed, 18 Jan 2012 18:39:12 GMT

Hello all, I've been searching for a discussion about this all this afternoon but wondered if anyone else has come across my issue here. I've just recently needed to load some data from KML/KMZ files onto my map - which luckily has been considered in the form of the KmlLayer class. My few experiments have been promising except for this: I have some KML documents that have a document schema defined to add custom elements and change the name of the Placemark tag to something different. It appears 'out-of-box' the KmlLayer won't recognize this schema and just not load any of the KML but apparently not throw an error either. Using a text editor I replaced the custom name for 'Placemark' back to 'Placemark' and the points rendered as expected.

Does anyone know of a way to get it to notice & recognize the rules of the <Schema>?

Re: KmlLayer with a schema?

DominiqueBroux — Thu, 19 Jan 2012 09:00:53 GMT

I have some KML documents that have a document schema defined to add custom elements and change the name of the Placemark tag to something different.

I didn't know that the schema allowed to change the name of the tags.
Could you share your file? I am interested in

Thanks

Re: KmlLayer with a schema?

ZachPride — Thu, 19 Jan 2012 13:25:59 GMT

Sure thing. Here is what I'm working with in this particular instance

[HTML]
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2">
<Document>
<name>Pirate_Master_05_09</name>
<Schema parent="Placemark" name="S_Pirate_Master_05_09_SSSDSSSSS">
<SimpleField type="wstring" name="VESSEL"></SimpleField>
<SimpleField type="wstring" name="DATE"></SimpleField>
<SimpleField type="wstring" name="LAT"></SimpleField>
<SimpleField type="double" name="LON"></SimpleField>
<SimpleField type="wstring" name="HOSTAGES"></SimpleField>
<SimpleField type="wstring" name="RANSOM_PAID"></SimpleField>
<SimpleField type="wstring" name="STATUS"></SimpleField>
<SimpleField type="wstring" name="COMMENTS"></SimpleField>
</Schema>

        <Style & StyleMap set here, seem typical enough>

        <Folder id="layer 0">
<name>Pirate_Master_05_09</name>
<S_Pirate_Master_05_09_SSSDSSSSS>
   <name>M/V MARAN CENTAURUS</name>
   <description><![CDATA[VESSEL = M/V MARAN CENTAURUS<br>DATE = 291615Z NOV 09<br>LAT = 04.603209N<br>LON = 58.8419<br>HOSTAGES = 28<br>RANSOM_PAID = Unknown<br>STATUS = Ongoing<br>COMMENTS = None<br>]]></description>
   <styleUrl>#default+nicon=http://maps.google.com/mapfiles/kml/pal4/icon57.png+hicon=http://maps.google.com/mapfiles/kml/pal4/icon49.png</styleUrl>
   <Style id="inline">
    <IconStyle>
     <color>ff0000ff</color>
     <colorMode>normal</colorMode>
     <Icon>
      <href>http://maps.google.com/mapfiles/kml/shapes/ferry.png</href>
     </Icon>
    </IconStyle>
    <LineStyle>
     <color>ff0000ff</color>
     <colorMode>normal</colorMode>
    </LineStyle>
    <PolyStyle>
     <color>ff0000ff</color>
     <colorMode>normal</colorMode>
    </PolyStyle>
   </Style>
   <Point>
    <coordinates>58.84192500000003,4.603209000000006,0</coordinates>
   </Point>
   <VESSEL>M/V MARAN CENTAURUS</VESSEL>
   <DATE>291615Z NOV 09</DATE>
   <LAT>04.603209N</LAT>
   <LON>58.841925</LON>
   <HOSTAGES>28</HOSTAGES>
   <RANSOM_PAID>Unknown</RANSOM_PAID>
   <STATUS>Ongoing</STATUS>
   <COMMENTS>None</COMMENTS>
</S_Pirate_Master_05_09_SSSDSSSSS>
                ...
                ...
[/HTML]

So, as you can see the Schema is replacing <Placemark> with <S_Pirate_Master_05_09_SSSDSSSSS>. I didn't know you could do this either but whoever authored this particular file seems to think so. Like I said I did a find and replace and re-hosted the file for testing and lo-and-behold the points were plotted and styled as shown. I should also note that Part B of my problem is that those custom elements at the bottom of the 'Placemark' are also not being picked up in the Attributes of the points. They seem to have (rather poorly) also provided them in the <description> element but I don't want to depend on all potential files doing so. They could very well have provided a simple paragraph in the description & custom elements for metadata.

Re: KmlLayer with a schema?

DominiqueBroux — Thu, 19 Jan 2012 14:30:29 GMT

OK I got the problem : 'Parent' schema attribute is no more in the standard KML 2.2.

Schema is defined this way in the OGC 2.2 specifications:
<Schema name="string" targetId="NCName">

<SimpleField type=string" name="string"> <displayName>...</displayName>  Field>

</Simple</Schema>

As you can see, there is no way to define the Parent. This practice has been superseded in KML 2.2 by the use of ExtendedData.

So, this case is not supported (and, likely, will never be supported) by the SL implementation of the KML layer.

If needed, you can get the KML layer sources on codeplex and adapt them by yourself.
Sorry not to have better proposal.:(

Re: KmlLayer with a schema?

ZachPride — Thu, 19 Jan 2012 16:57:08 GMT

Sorry not to have better proposal.:(

Oh not a problem at all! I'm glad to have a definitive answer. I had begun to think @parent was phased out, after searches this morning for that attribute as it would apply to Schema were going no where... I think I'm going to try and talk with the KML author before I have to modify ESRI's source code. You can probably imagine the rest of this KML is as strangely composed and out of date as it looks. Who would want to change <Placemark> to that in the first place?! :confused: