Now that we have the XML feed, we need to create an XSL file
to transform it into HTML so that we can display it on our web site. After we
have decided which nodes to display from the XML feed we need to decide how to
transform them with XSL.
Looking at the XSL in Listing 2 you will notice that a test
is made to see if certain nodes exist before displaying them. The reason for
this is that this example uses a default XML file that gets loaded if the XML
feed is unavailable.
You may have noticed in the XML feed in Listing 1 that some
of the nodes contained a value of "NA." The NWS is using this value
to indicate that there is no currently applicable data for that node. Some
examples of nodes that might contain NA values are heat index, wind chill, and
wind gust. This NA value can be used to determine whether or not to display a
certain node. For example, there are only heat index or wind chill values under
certain conditions and sometimes there is neither. You do not want to display
the label for heat index followed by NA. So, the example XSL checks to see if the
wind chill node is NA before displaying it.
I have created an example XSL style sheet which is shown in
Listing 2. Name the XSL file Weather.xsl and place it in the App_Data folder of
your web application.
Listing 2 - This is the XSL file that we will use
to transform the XML weather feed.
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" method="html" />
<xsl:template match="/">
<!-- This is an XSL template file. -->
<table bgcolor="#eeeeee" cellspacing="0" cellpadding="1">
<tr bgcolor="lightsteelblue">
<td colspan="2">
<xsl:value-of select="current_observation/location"/>
<br/>
<xsl:value-of select="current_observation/observation_time"/>
</td>
</tr>
<xsl:if test="current_observation/weather != ''">
<tr>
<td>
Weather:
</td>
<td>
<xsl:value-of select="current_observation/weather"/>
</td>
</tr>
</xsl:if>
<xsl:if test="current_observation/temperature_string != ''">
<tr>
<td>
Temperature:
</td>
<td>
<xsl:value-of select="current_observation/temperature_string"/>
</td>
</tr>
</xsl:if>
<xsl:if test="current_observation/relative_humidity != ''">
<tr>
<td>
Humidity:
</td>
<td>
<xsl:value-of select="current_observation/relative_humidity"/> %
</td>
</tr>
</xsl:if>
<xsl:if test="current_observation/wind_string != ''">
<tr>
<td>
Wind:
</td>
<td>
<xsl:value-of select="current_observation/wind_string"/>
</td>
</tr>
</xsl:if>
<xsl:if test="current_observation/windchill_string != '' and
current_observation/windchill_string != 'NA'">
<tr>
<td>
Wind Chill:
</td>
<td>
<xsl:value-of select="current_observation/windchill_string"/>
</td>
</tr>
</xsl:if>
<xsl:if test="current_observation/heat_index_string != '' and
current_observation/heat_index_string != 'NA'">
<tr>
<td>
Heat Index:
</td>
<td>
<xsl:value-of select="current_observation/heat_index_string"/>
</td>
</tr>
</xsl:if> </table>
</xsl:template>
</xsl:stylesheet>
