Bonjour , 

La solution était de modifier en %Stream.GlobalCharacter pour la balise contenu lors du Correlate. 

Cela fonctionne parfaitement en fait il me manquait le XML Adaptor. 

Merci beaucoup

Merci @Lorenzo Scalese ,

En revanche je me retrouve avec un "Method does not exist" lié au reader.Next 

J'ai pourtant mes 2 classes : 

Class replic.msg.XML Extends (%Persistent, %XML.Adaptor, Ens.Request)
{
Property Table As %String(MAXLEN = "");
Property Action As %String(MAXLEN = "");
Property CleIris As %String;
Property nIdentifiant As %String;
Property IdIris As %String;
Property Contenu As %String;
}

Class replic.msg.XMLStructure Extends %Persistent
{
Parameter XMLNAME = "data";
Property tablename As list Of replic.msg.XML(XMLPROJECTION = "ELEMENT");
}

Method readXML(pRequest As Ens.StreamContainer, pResponse As replic.msg.XMLStructure) As %Status
{
    set tsc             = $$$OK
    set reader          = ##class(%XML.Reader).%New()

    //set pResponse       = ##class(replic.msg.XMLStructure).%New()
    #dim data  As replic.msg.XMLStructure
	#dim tableName As replic.msg.XML
    do pRequest.Stream.Rewind()

    do reader.Correlate("data","replic.msg.XMLStructure")
    set status              = reader.OpenStream(pRequest.Stream)
    
    Do reader.Next(.data)

    Set key = ""
	Set tableName = data.tablename.GetNext(.key)
	While key '= "" {
		set ^debug() = tableName.Table
		Set tableName = data.tablename.GetNext(.key)
	}
	}

Mon erreur : 

ERREUR <Ens>ErrException: <METHOD DOES NOT EXIST>Next+25^%XML.Reader.1 *XMLNew,replic.msg.XMLStructure -- - connecté en tant que '-' numéro - @''