LAYER

LAYER

Used in: CONFIG   REQUEST   RESPONSE
Servers: Image   Query   Feature   Extract   Geocode   ArcMap
Parent elements: GET_FEATURES   GET_GEOCODE   GET_IMAGE   LAYERS   MAP

<LAYER	Attribute Description Table
When parent element is GET_FEATURES, GET_GEOCODE: *id ="string"* When parent element is LAYERS in a GET_IMAGE request or map configuration file: *id ="string"* When parent element is LAYERS in an IMAGE response: *featurecount ="string"* *id ="string"* *name ="string"* When parent element is MAP, GET_IMAGE, GET_EXTRACT: *id ="string"* type ="featureclass \| acetate \| image" maxscale ="string" minscale ="string" name ="string" visible ="true \| false" [true] > When parent element is GET_FEATURES, GET_GEOCODE: No Child Elements When parent element is GET_IMAGE and LAYER type="featureclass" or "image" - ArcMap Server: <DATASET... /> <QUERY... /> [Either SPATIALQUERY or QUERY but not both] <SPATIALQUERY... /> [Either SPATIALQUERY or QUERY but not both] When parent element is LAYERS: No Child Elements When parent element is MAP or GET_IMAGE and LAYER type="acetate" - Image and ArcMap Servers: (m) <OBJECT... /> When parent element is MAP or GET_IMAGE and LAYER type="image" - Image Server: <DATASET... /> <COORDSYS... /> <IMAGEPROPERTIES... /> <RASTER_RENDERER... /> [Only valid with MAP] When parent element is MAP, GET_IMAGE, or GET_EXTRACT and LAYER type="featureclass" - Image and Extract Servers: <DATASET... /> <COORDSYS... /> <DENSIFY... /> <QUERY... /> [Either SPATIALQUERY or QUERY but not both] <SPATIALQUERY... /> [Either SPATIALQUERY or QUERY but not both] (m) <EXTENSION... /> [Only valid with MAP] <GROUPRENDERER... /> [Or] <SCALEDEPENDENTRENDERER... /> [Or] <SIMPLELABELRENDERER... /> [Or] <SIMPLERENDERER... /> [Or] <VALUEMAPLABELRENDERER... /> [Or] <VALUEMAPRENDERER... /> [Or] </LAYER >
Bold: Attribute or child element is required. (m): Child element can be used multiple times.

Description:

When parent element is MAP, LAYER defines a map layer. Layers of type featureclass use point, line, and polygon data from shapefiles or ArcSDE. Layers of type image are used for displaying images. Layers of type acetate are used to display additional objects on the map.
In a GET_IMAGE or GET_EXTRACT request, LAYER can be used two ways. It can be used to add a dynamic layer to an existing Image Service. It can also be used to add an existing Image Service layer in a modified format. This latter functionality is most commonly used to show subsets of an existing layer such as selected features.
Used in a GET_GEOCODE request to identify which layer is to be geocoded.
Used in a GET_FEATURES request to identify from which layer to get feature information.
Used with LAYERS in LEGEND to identify which layers in a service or request should not be included in the legend.
Used in an IMAGE response to give information on the returned vector, image, and acetate layers including name, ID, and number of features in the map.

Restrictions:

ID for each layer must be unique within the service and within any layers added dynamically in a request.
In a request to an ArcMap Image Service, LAYER cannot be used to add new data in a dynamic layer.
Use only one renderer at a time.
Identify and query cannot be made on dynamic layers.
EXTENSION and RASTER_RENDERER are valid only when parent element is MAP, and not in a request.

Notes:

In order to add a dynamic layer with new data in a GET_IMAGE request, the attribute dynamic must be set to true in the MAP element in a map configuration file. Valid only with Image Server.
In a GET_IMAGE or GET_EXTRACT request, LAYER is used to create a new layer. Use LAYERDEF to change an existing layer's rendering or to turn the layer on or off. For more information about using LAYER in a request, including more examples, see Using GET_IMAGE and IMAGE with Image Services, Using GET_IMAGE and IMAGE with ArcMap Image Services, and Using GET_EXTRACT and EXTRACT.
For ArcSDE layers, DATASET must be defined before renderer.
Many OBJECTs can be defined in one acetate layer.
Scales can be set in ArcXML using a relative scale or by calculating the number of map units per pixel. A relative scale represents the scale in a ratio such as 1:24000. In this example, 1 meter equals 24000 meters, or 1 inch equals 24000 inches. When using relative scale, always use a colon (:) between the two values.

Map units per pixel refers to the number of meters, feet, or decimal degrees represented by one pixel in a map. To convert from a relative scale to map units per pixel, the size of a pixel must first be calculated. The formula for finding the number of meters in a pixel is 0.0254 / dpi where:
- The value 0.0254 is the number of meters in an inch.
- Dpi is the dpi set in the ArcIMS service or request. If no dpi is set in the service or request, the dpi is assumed to be 96.
As an example of calculating pixel size, if the dpi is 96, the pixel size is 0.0254 / 96 or 0.000265 m.

Once the pixel size is known, the relative scale can be converted to map units per pixel:
1. If the scale is in meters. To calculate the number of meters per pixel, take the relative scale and multiply by the pixel size (0.000265). For example, if the relative scale is 1:24000, then the number of meters per pixel is 24000 * 0.000265, or 6.36 meters.
2. If the scale is in feet. Do the calculation for meters (#1). Multiply the result by 3.28 (the number of feet in a meter). For example, if the number of meters per pixel is 6.36, the number of feet per pixel is 6.36 * 3.28, or 20.86 feet.
3. If the scale is in decimal degrees. For these calculations, the earth is assumed to be an exact circle with a circumference of 40030.174 km. One degree is 111.195 km (40030.174/360 degrees), or 111195 meters. To calculate the number of degrees, first do the calculation for meters (#1). Next, divide the result by 111195. For example, if the number of meters per pixel is 6.36, the number of degrees per pixel is 6.36 / 111195, or 0.0000571968.

Attribute Descriptions for LAYER:

When parent element is GET_FEATURES, GET_GEOCODE:

Attribute	Usage	Back to Top
id	1 ID as specified in map configuration file. For a request to be valid, the ID used in the request must have a match in the map configuration file.

When parent element is LAYERS in a GET_IMAGE request or map configuration file:

Attribute	Usage	Back to Top
id	1 ID as specified in map configuration file or the request. For a legend list to be valid, the ID used must have a match in the map configuration file or the request.

When parent element is LAYERS in an IMAGE response:

Attribute	Usage	Back to Top
featurecount	1 For shapefile and ArcSDE layers, counts the number of features shown on the map. For image layers, counts the number of images present in the map. For acetate layers, counts the number of times OBJECT is used in a layer.
id	2 ID as specified in map configuration file or request.
name	3 Name as specified in map configuration file or request.

When parent element is MAP, GET_IMAGE, GET_EXTRACT:

Attribute	Usage	Back to Top
id	1 Unique ID for a layer. The ID can be any combination of alpha and numeric characters. If used in a request to extract data, the characters must be in English and valid for a filename unless the extract EXTENSION for the layer is used.
maxscale	2 Maximum scale to display map using a relative scale such as 1:24000. Scale can also be calculated as the number of map units per pixel.
minscale	3 Minimum scale to display map using a relative scale such as 1:24000. Scale can also be calculated as the number of map units per pixel.
name	4 Layer name. Can be an alias.
type	5 Specifies layer type. Use "featureclass" for shapefiles and ArcSDE vector layers. Use "image" for raster image files, GRIDs, and ArcSDE raster layers. Use "acetate" for adding graphics on top of the map.
visible	6 Specifies layer visibility.

Examples for LAYER:

Example 1: When in CONFIG.

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Example 2: Map configuration file where layers with ID of "0" and "1" are removed from the legend list.

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<?xml version="1.0" encoding="UTF-8"?>
<ARCXML version="1.1">
  <CONFIG>
    <ENVIRONMENT>
      <LOCALE country="US" language="en" variant="" />
      <UIFONT color="0,0,0" name="Arial" size="12" style="regular" />
      <SCREEN dpi="96" />
    </ENVIRONMENT>
    <MAP dynamic="true" >
      <PROPERTIES>
      <ENVELOPE minx="-180.0" miny="-90.0" maxx="180.0" maxy="90.0" name="Initial_Extent" />
      <MAPUNITS units="decimal_degrees" />
      <LEGEND title="Legend" font="Arial" autoextend="true" columns="1" width="170" height="300" backgroundcolor="255,255,0" >
        <LAYERS>
          <LAYER id="0"/>
          <LAYER id="1"/>
        </LAYERS>
      </LEGEND>
      </PROPERTIES>
      <WORKSPACES>
        <SHAPEWORKSPACE name="shp_ws-0" directory="<path to WORLD ESRIDATA>" />
        <SHAPEWORKSPACE name="shp_ws-2" directory="<path to USA ESRIDATA>" />
        <SHAPEWORKSPACE name="shp_ws-3" directory="<path to CANADA ESRIDATA>" />
      </WORKSPACES>
      <LAYER type="featureclass" name="WORLD30" visible="true" id="0">
        <DATASET name="WORLD30" type="polygon" workspace="shp_ws-0" />
        <SIMPLERENDERER>
          <SIMPLEPOLYGONSYMBOL filltype="solid" fillcolor="0,153,255" />
        </SIMPLERENDERER>
      </LAYER>
      <LAYER type="featureclass" name="CNTRY94" visible="true" id="1">
        <DATASET name="CNTRY94" type="polygon" workspace="shp_ws-0" />
        <SIMPLERENDERER>
          <SIMPLEPOLYGONSYMBOL filltype="solid" fillcolor="255,255,153" />
        </SIMPLERENDERER>
      </LAYER>
      <LAYER type="featureclass" name="United States" visible="true" id="2">
        <DATASET name="STATES" type="polygon" workspace="shp_ws-2" />
        <SIMPLERENDERER>
          <SIMPLEPOLYGONSYMBOL filltype="solid" fillcolor="255,0,0" />
        </SIMPLERENDERER>
      </LAYER>
      <LAYER type="featureclass" name="Canada" visible="true" id="3">
        <DATASET name="province" type="polygon" workspace="shp_ws-3" />
        <SIMPLERENDERER>
          <SIMPLEPOLYGONSYMBOL filltype="solid" fillcolor="0,153,0" />
        </SIMPLERENDERER>
      </LAYER>
      <LAYER type="featureclass" name="World Cities" visible="true" id="4">
        <DATASET name="CITIES" type="point" workspace="shp_ws-0" />
        <SIMPLERENDERER>
          <SIMPLEMARKERSYMBOL color="102,0,102" width="8.0" />
        </SIMPLERENDERER>
      </LAYER>
    </MAP>
  </CONFIG>
</ARCXML>

Example 3: When used with LAYERS to remove layers with ID of "0" and "1" from the legend list.

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<?xml version="1.0" encoding="UTF-8"?>
<ARCXML version="1.1">
  <REQUEST>
    <GET_IMAGE>
      <PROPERTIES>
        <LEGEND title="Legend" font="Arial" autoextend="true" columns="1" width="170" height="300" backgroundcolor="255,255,0" >
          <LAYERS>
            <LAYER id="0"/>
            <LAYER id="1"/>
          </LAYERS>
        </LEGEND>
        <DRAW map="false"/>
      </PROPERTIES>
    </GET_IMAGE>
  </REQUEST>
</ARCXML>

Example 4: Identifying a layer by its ID in a GET_FEATURES request.	Back to Top
<?xml version="1.0" encoding="UTF-8"?> <ARCXML version="1.1"> <REQUEST> <GET_FEATURES featurelimit="25" beginrecord="0" outputmode="xml" geometry="false" envelope="true" compact="true"> <LAYER id="4" /> <SPATIALQUERY subfields="#ALL#" where="NAME = 'Los Angeles'" > </SPATIALQUERY> </GET_FEATURES> </REQUEST> </ARCXML>

Example 5: IMAGE response showing details on layers in the requested ArcIMS service.

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<?xml version="1.0" encoding="UTF8"?>
<ARCXML version="1.1">
  <RESPONSE>
    <IMAGE>
      <ENVELOPE minx="-180" miny="-135" maxx="180" maxy="135" />
      <LAYERS>
        <LAYER name="CNTRY94" id="0" featurecount="165" />
        <LAYER name="STATES" id="1" featurecount="51" />
        <LAYER name="province" id="2" featurecount="12" />
      </LAYERS>
      <OUTPUT file="c:\arcims\output\world_MYCOMPUTER3633699.jpg" url="http://mycomputer.domain.com/output/world_MYCOMPUTER3633699.jpg" />
    </IMAGE>
  </RESPONSE>
</ARCXML>