The pipeline
<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:option name="WHOST" select="'http://localhost:8246'" static="true"/>
<p:output port="result"/>
<p:http-request href="{$WHOST}/service/echo" method="post" parameters="map{'override-content-type' : 'application/json'}">
<p:with-input>
<p:inline>
<doc/>
</p:inline>
</p:with-input>
</p:http-request>
</p:declare-step>
