Getting ICMENOSESSION error while calling SAP S4 webservice from SAP CPI

[SinhaSouvik]

Hi Expert,

We are working on scenarios in SAP CPI to call SAP S4 webservice to get the data in request/reply way. There are multiple calls happening to S4 webservice using SOAP 1.x receiver adapter.

FLOW:  SAP CPI <-> SAP SCC <-> SAP S4 (on-prem)

Modernize RFC Receiver Communications into API-Based Protocols in Cloud Integration. Link to understand the scenario in details: https://developers.sap.com/tutorials/modernize-rfc-receiver.html

In S4, webservice is linked to function module based on the request payload we are sending from CPI function module is getting executed based on the logic written in it then giving back the response immediately.

Problem statement:

• Webservice calls are getting executed successfully for few initial calls. Some of the execution whole integration is getting executed successfully without failure.
  But sometimes suddenly getting failed with error: "org.apache.cxf.interceptor.Fault: Could not send Message., cause: org.apache.cxf.transport.http.HTTPException: HTTP response '400: Bad Request. <!-- This error page was generated by ICM (-)! -->
  <!-- Error code: ICMENOSESSION "
• We are not able to see any logs in SRT_MONI or SXMB_MONI about this failure in S4. Also tried to check in SRT_UTIL but no luck.

From our end we have tried to execute the integration by doing multiple changes:

• Made HTTP session reuse 'none' in CPI and enableSession parameter false in S4 wsdl setting. (KBA:

  https://me.sap.com/notes/0003419590)

• Also tried to remove allow chunking in SAP CPI SOAP adapter configuration.
• All cases we are throwing same error.

Please suggest further if you also encountered similar kind of issues. let me know possible resolution of this issue.

Regards,

Souvik

[Ulrich_Schmidt]

Is there a compelling reason, why you can't simply use RFC directly? If the interface is originally available as RFC-enabled function module, then this is usually the better choice. Switching to a different protocol, just because it is "more modern", is a bad idea, in my opinion.

(BTW: interesting, that people are trying to "modernize" RFC interfaces by replacing them with HTTP-based interfaces... The HTTP protocol is older than the RFC protocol...! 🙂 HTTP was designed for transferring text files (HTML pages) via "one-shot" connections. RFC was designed for transferring business data (mix of text, floating point, BCD, integer data) via stateful connections. Consequently, RFC is better suited when you try to transfer business data: it is easier to use, more robust and much faster. Performance tests have shown:

• in fast networks (LAN) - where serialization/deserialization time is the main contributor - RFC is about 14-19 times faster than WebService/SOAP
• in slow networks (internet) - where network time is the main contributor - RFC is 4-5 times faster than WebService/SOAP

depending on the scenario and the type of data.)

[SinhaSouvik]

Hi @Ulrich_Schmidt ,

As per the SAP 'clean core' strategy strongly encourages external interaction to go through clean and documented APIs (reference link). In that case, I believe SOAP or ODATA is preferrable. Please share your suggestion further. 

Regards,

Souvik