Datapower extension functions and extension elements

Question

I am currently involved into Websphere Datapower SOA appliance development. However I am getting confused between two entities. Datapower extension functions and elements.

Can someone tell me what is main difference between the two and why in Datapower extension function namespace we only give:

xmlns:dp="http://www.datapower.com/extensions"

while in Datapower extension elements we mention the following:

xmlns:dp="http://www.datapower.com/extensions"
extension-element-prefix="dp"
exclude-result-prefix="dp"

Answer 1

Datapower uses XSLT to manipulate any part of incoming/outgoing message. Now while implementing this feature it was realized that XSLT functions needs to be enhanced to support the particular processing need of datapower. As a result datapower extended the XSLT function library, in some cases extending existing functions [like xsl:message] and in other cases adding new elements [like dp:set-response-header] to XSLT library. As a pre-requisite to do this, one needs to define a namespace for this extended library and hence the new datapower namespace.

Answer 2

extension-element-prefix="dp" :- Used to inform XSLT process that elements with 'dp' are extension elements. needs more process towards elements. (can't simply print)

exclude-result-prefix="dp" :- If no need to send dp namespace in the output payload as it is internal processing namespace for extension element or function. We can declare many namespace prefix with spaces.