[OpenLayers-Users] Context Documents - WMC.html example

[McGraw, Joanne]

Hello everyone,

I have been trying to load a context document through the OpenLayers
wmc.html example for a couple of days now to no avail. I am using
OpenLayers 2.6 and MapServer 5.0.2.

The context document I would like to display is included below (the
first one); note the BoundingBox and Layer SRS and Extents, including
the layer's ol:maxExtent and ol:units. That first context document does
not display anything in the map in the wmc.html page but there is no
suggestion that a problem occurred anywhere along the way. The browser
"waits" for atlas.gc.ca and is eventually "Done", but no data displays.

The second context document below does display the layer defined in the
wmc.html map. The only things different between the two context
documents are related to the SRS and extents. In the second context
document, I use lat/long values and don't bother trying to set the
ol:maxExtents and ol:units specifically. I just leave them at the
defaults.

When I look at the results of the GetCapabilities request to the
atlaswms_en service, the definition for the "can_1m_bound" layer
suggests I should be able to get the map using the EPSG:42304
projection. For verification, the GetCapabilities xml can be obtained
with:
http://atlas.gc.ca/cgi-bin/atlaswms_en?service=WMS&version=1.1.1&request
=getCapabilities 

Are context documents using projections and extents that are not
lat/long supported? I can't find any documentation suggesting that this
is the case and that there is a problem with what I am trying to do.
Assuming other SRS besides EPSG:4326 are supported, can anyone suggest
where I am going wrong below?

Cheers,
jtm

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<ViewContext xmlns="http://www.opengis.net/context" version="1.1.0"
id="atlas_en" xsi:schemaLocation="http://www.opengis.net/context
http://schemas.opengis.net/context/1.1.0/context.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<General>
    <Window width="512" height="256"/>
    <BoundingBox SRS="EPSG:42304" minx="-2700000" miny="-725000"
maxx="3380000" maxy="4650000"/>
    <Title>NLWIS Map</Title>
        <Extension>
            <ol:maxExtent xmlns:ol="http://openlayers.org/context"
minx="-2750000" miny="-900000" maxx="3250000" maxy="3900000"/>
        </Extension>
  </General>
  <LayerList>
        <Layer queryable="1" hidden="0">
            <Server service="OGC:WMS" version="1.1.1" title="National
Atlas WMS">
                <OnlineResource xlink:type="simple"
xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:href="http://atlas.gc.ca/cgi-bin/atlaswms_en?"/>
            </Server>
            <Name>can_1m_bound</Name>
            <Title>Boundaries (1:1 000 000)</Title>
            <SRS>EPSG:42304</SRS>
            <Extension>
                <ol:maxExtent xmlns:ol="http://openlayers.org/context"
minx="-2700000" miny="-725000" maxx="3380000" maxy="4650000"/>
                <ol:units
xmlns:ol="http://openlayers.org/context">meters</ol:units>
            </Extension>
        </Layer>
  </LayerList>
</ViewContext>

------------------------------------------------------------------------
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<ViewContext xmlns="http://www.opengis.net/context" version="1.1.0"
id="atlas_en" xsi:schemaLocation="http://www.opengis.net/context
http://schemas.opengis.net/context/1.1.0/context.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<General>
    <Window width="512" height="256"/>
    <BoundingBox SRS="EPSG:4326" minx="-142" miny="40.5" maxx="-51.5"
maxy="84.5"/>
    <Title>NLWIS Map</Title>
        <Extension>
            <ol:maxExtent xmlns:ol="http://openlayers.org/context"
minx="-2750000" miny="-900000" maxx="3250000" maxy="3900000"/>
        </Extension>
  </General>
  <LayerList>
        <Layer queryable="1" hidden="0">
            <Server service="OGC:WMS" version="1.1.1" title="National
Atlas WMS">
                <OnlineResource xlink:type="simple"
xmlns:xlink="http://www.w3.org/1999/xlink"
xlink:href="http://atlas.gc.ca/cgi-bin/atlaswms_en?"/>
            </Server>
            <Name>can_1m_bound</Name>
            <Title>Boundaries (1:1 000 000)</Title>
            <SRS>EPSG:4326</SRS>
            <Extension>
                <ol:maxExtent xmlns:ol="http://openlayers.org/context"
minx="-142" miny="40.5" maxx="-51.5" maxy="84.5"/>
            </Extension>
        </Layer>
  </LayerList>
</ViewContext>

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