Message mapping with signature changed

Question

Hello,
I have a mapping whose incoming and outgoing message has the same message type, let's say the message type for both in and out message is *MT_Material *. The mapping basically copy all data from in message to out message, however, the out message is only created based on certain condition. Therefore I changed the signature to define the Occurance of the out message as 0..1 while the in message has occurance of 1.
Things work fine, out message only contains data when the condition is fullfilled. However the mapping program expects incoming message like;
<?xml version="1.0" encoding="UTF-8"?>
<ns0:Messages xmlns:ns0="http://sap.com/xi/XI/SplitAndMerge">
   <ns0:Message1>
      <ns1:MT_Material xmlns:ns1="http://mynamespace">
         <MatNo>123345</MatNo>
         <MatText>
            <Language>en</Language>
            <Text>esx</Text>
         </MatText>
         <MatText>
            <Language>fr</Language>
            <Text>esxfr</Text>
         </MatText>
      </ns1:MT_Material>
   </ns0:Message1>
</ns0:Messages>
Note the xml tags in bold are needed because of the signature change (occurance change). However the outbound interface is based on the message type of MT_Material, thus the sender will NOT send the xml tags in bold, rather following message is sent:
<?xml version="1.0" encoding="UTF-8"?>
      <ns0:MT_Material xmlns:ns1="http://mynamespace">
         <MatNo>123345</MatNo>
         <MatText>
            <Language>en</Language>
            <Text>esx</Text>
         </MatText>
         <MatText>
            <Language>fr</Language>
            <Text>esxfr</Text>
         </MatText>
      </ns0:MT_Material>
Message in this format is NOT expected by the mapping program with changed signature, thus mapping is does NOT result in the right result.
So what should I do with it? looks like change signature doesn't make any sense because it expects different outbound message format as the one without signature changed.
Basically mapping is PI internal stuff, the sender should not be aware of it, thus sender should just send a message based on the message interface which is based on MT_Material.
what do you thnk of this?
Any

Answer 1

Hi Jayson
You are correct to some extent we should not force the vendor to send a tag to satisfy middleware. But if the tag is required for the business process what can be done other than forcing as a rule to vendor
As PI is a XML based tool where XML is tied to a XSD all messages need to follow XSD. Now in your requirement we need to meet the condition for generating the output. Being a middle ware PI is not meant for holding the messages or used as an end point for some communication. It works on two engines and we need to pass IS without error. Mapping will work at IS and if it failed its an error but we have to satisfy condition.
I have faced similar requirement to yours. I had routed the messages through email to vendor when no output need to be generated as they were incorrect and doesn't follow business rule of the process.
We can check with Xpath or either some the way we discussed above in case condition is not met
Thanks
Gaurav