SAP CPI: Control your messages with custom header

Introduction

Recently I encountered a basic router scenario. However the information I could use as a condition was not included in the message itself. I had to pass it to CPI, but didn’t want to enrich the message and mess it up. I figured out that custom header would be the great solution, however as it occurred, it wasn’t so easy (now it is of course).

Steps

So you would like to pass a custom header to CPI.

SoapUI

In SoapUI you would pass it on like this:

ABAP

In ABAP it is possible thanks to the best library cl_http_client:

    lo_httpclient->request->set_header_field(
        name  = ‘CustomHeader‘
        value = ‘100‘ ).

SAP CPI

This is the most important step – you need to enable custom headers so CPI can accept them. Just go to your iFlow, click on the white space behind the flow and you will be displayed a “Integration Flow” menu. Go to “Runtime Configuration” and fill “Allowed Header(s)”.

You could also type *. In this case CPI would accept all incoming headers.

Read your header

Now your custom header will be visible in CPI. In order to read the value use the expression

${header.CustomHeader}. Of course you could get access to any header using such expression. In my case I would use it in router step.

Summary

I think it is a smarter and safer way to control your message flow. Instead of messing with payload you “hide” your controls in different part of message exchange. What do you think?