We now just add the [p:]url step to the pipeline to call the web service:

<p:pipe xmlns:p="urn:publicid:IDN+smallx.com:pipeline:1.0" name="changeme"
   xmlns:c="urn:publicid:IDN+smallx.com:component-language:1.0"
   xmlns:f="urn:publicid:IDN+smallx.com:server:forms:post:1.0"
   xmlns:param="urn:publicid:IDN+smallx.com:server:parameters"
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:t="http://www.smallx.com/services/tideinfo/2005"
>

<p:template>
<xsl:param name="param:server"/>
   <c:url-post href="{$param:server}tideinfo-service/tideinfo.pd">
   <t:tideinfo location="{/f:form/f:parameter[@name='location']}"/>
   </c:url-post>
</p:template>

<p:url/>

</p:pipe>

The result of this pipeline is the tide information.