2 . SAP S/4HANA and SAP Cloud Platform Enterprise Messaging According to the Event Driven Architecture

Let’s take a closer look.
The architecture may look like this.

Events that occur in S/4HANA are sent to SAP Cloud Platform Enterprise Messaging.
It is also possible to broadcast from Enterprise Messaging to multiple runtimes.

In the diagram above, three types of systems (SAP Cloud Platform Integration, Extension Factory Serverless Runtime and web application) receive data from Enterprise Messaging, but you can freely decide which system receives it.

I will briefly introduce each component.

1.SAP S/4HANA Enterprise Event Enablement feature

 

 

 

 

 

 

 

With the feature of Enterprise Event Enablement of S/4HANA, you can pass the S/4HANA event to the external systems via the middleware called SAP Cloud Platform Enterprise Messaging. The  supported communication protocol between SAP S/4HANA and SAP Cloud Platform Enterprise Messaging will be MQTT (over Websocket).

https://help.sap.com/viewer/810dfd34f2cc4f39aa8d946b5204fd9c/1909.002/en-US/c200f98fadb64ff1828ed5696c86fca2.html

2.SAP Cloud Platform Enterprise Messaging

SAP Cloud Platform Enterprise Messaging is a middleware service for asynchronous messaging. By placing Enterprise Messaging in between, it is possible to realize asynchronous messaging that separates the sending process and the receiving process, and to level the message processing load.

https://discovery-center.cloud.sap/serviceCatalog/enterprise-messaging

3.SAP Cloud Platform Extension Factory, Serverless Runtime

 

 

 

 

 

 

SAP Cloud Platform Extension Factory, Serverless Runtime is a runtime for building a serverless environment in SAP Cloud Platform. Just like an ordinary serverless environment like AWS Lambda, it is possible to execute logic in an event-driven manner and you don’t need to care about server resources or sever management.

https://discovery-center.cloud.sap/serviceCatalog/extension-factory-serverless-runtime

4.SAP Cloud Platform Integration

 

 

 

 

 

 

SAP Cloud Platform Integration is a middleware service for the Process Integration (iPaaS) on SAP Cloud Platform. Currently, multiple Integration services (Cloud Platform Integration, API Management, Open Connector) have been integrated and are now offered as an Integration Suite.  SAP Cloud Platform Integration is the core component of it.

https://discovery-center.cloud.sap/serviceCatalog/integration-suite

 

Another important point for the we don’t pass the entire data of the business object for the event messaging.The payload of the event only includes the type of business object (Purchase order, Sales Order etc.), key information, and action( creation, change, or deletion).

Here is an example of the palyload.
We can know this is en event of Outbound Delivery Change and the document number is “00800005”.

{"eventType":"BO.OutboundDelivery.Changed",
"cloudEventsVersion":"0.1",
"source":"https://sap.corp",
"eventID":"QgEKigAJHuqn0laStiBciA==",
"eventTime":"2020-05-25T14:19:12Z",
"schemaURL":"https://sap.corp/sap/opu/odata/IWXBE/BROWSER_SRV/",
"contentType":"application/json",
"data":{"KEY":[{"OUTBOUNDDELIVERY":"0080000005"}]}}

Enterprise Messaging will simply pass the payload data just as it is and  when you received it with SAP Cloud Platform Integration, Serveless Runtime or custom application, it is necessary to pass the kay and access the API of S/4HANA to get the detailed information.

 

3 .SAP S/4HANA integration with SAP Cloud Platform Enterprise Messaging

From here, I will explain about the actual configuration in Step by Step.

Most of the steps are similar to this blog. One thing we need to remember is the blog below is using “trial” version of SAP Cloud Platform and the “plan” of Enterprise Messaging is different from the productive version.

https://blogs.sap.com/2019/09/16/sap-enterprise-messaging-for-s4hana-on-premises/

For this blog, I will use the plan for the production environment.

OK, then let’s start with the configuration on SAP Cloud Platform.

3.1 CLI Download and Login

In this blog, I will create the the service instance of Enterprise Messaging via CLI (Command Line interface) tool instead of the SAP Cloud Platform Cockpit Web screen.

If you have never used the Cloud Foundry CLI, I would recommend you to install it on your PC and try it out.

Click here to download Cloud Foundry CLI

https://docs.cloudfoundry.org/cf-cli/install-go-cli.html

This is the tutorial about the Cloud Foundry CLI and you will know how to login with CF CLI here.

https://developers.sap.com/tutorials/cp-cf-download-cli.html

 

3.2 Create a Service Instance

Let’s create a configuration file for creating a service instance of SAP Cloud Platform Enterprise Messaging. It is a JSON format text file like below on the local PC and name it “param.json”.

{
    "options": {
        "management": true,
        "messagingrest": true,
        "messaging": true
    },
    "rules": {
        "topicRules": {
            "publishFilter": [
                "${namespace}/*"
            ],
            "subscribeFilter": [
                "${namespace}/*"
            ]
        },
        "queueRules": {
            "publishFilter": [
                "${namespace}/*"
            ],
            "subscribeFilter": [
                "${namespace}/*"
            ]
        }
    },
    "version": "1.1.0",
    "emname": "EM1",
    "namespace": "SAPJP/EM1/S4HANA"
}

Create a service instance “em1” with the following command.
cf create-service enterprise-messaging default <service instance name> -c <option>

cf create-service enterprise-messaging default em1 -c param.json

Use the “cf service” command to check if the service was created successfully.
You can get information about the service instance with
cf service-<service instance name> .

cf service em1

name:             em1
service:          enterprise-messaging
tags:             
plan:             default
description:      Connect applications, services and systems across different landscapes.
documentation:    https://help.sap.com/viewer/bf82e6b26456494cbdd197057c09979f/Cloud/en-US/df532e8735eb4322b00bfc7e42f84e8d.html
dashboard:        
service broker:   sm-enterprise-messaging-service-broker-a6a59ffd-b691-49b4-b439-d4960acc2065

Showing status of last operation from service em1...

status:    create succeeded
message:   
started:   2020-05-24T23:39:31Z
updated:   2020-05-24T23:40:33Z

There are no bound apps for this service.

Upgrades are not supported by this broker.

 

3.3 Create a Service Key

When you use a service from an application, you can get the access information from the environment variable of the app by binding the app to the service. But if you want to access from an external system like this S/4HANA, we need to create a service key to get the access info.

Create the service key with the following command:
You can create a service key with cf create-service-key <service instance name> <service key name> .

cf create-service-key em1 em1-key

3.4 Get the Service Key

Specify to get access information from the service key.

Information can be obtained with cf service-key <service instance name> <service key name> .

cf service-key em1 em1-key

{
 "management": [
  {
   "oa2": {
    "clientid": "<client id value>",",
    "clientsecret": "<client secret value>",
    "granttype": "client_credentials",
    "tokenendpoint": "https://<tenant>.authentication.<region>.hana.ondemand.com/oauth/token"
   },
   "uri": "https://enterprise-messaging-hub-backend.cfapps.<region>.hana.ondemand.com"
  }
 ],
 "messaging": [
  {
   "broker": {
    "type": "sapmgw"
   },
   "oa2": {
    "clientid": "<client id value>",
    "clientsecret": "<client secret value>",
    "granttype": "client_credentials",
    "tokenendpoint": "https://<tenant>.authentication.<region>.hana.ondemand.com/oauth/token"
   },
   "protocol": [
    "amqp10ws"
   ],
   "uri": "wss://enterprise-messaging-messaging-gateway.cfapps.<region>.hana.ondemand.com/protocols/amqp10ws"
  },
  {
   "broker": {
    "type": "sapmgw"
   },
   "oa2": {
    "clientid": "<client id value>",
    "clientsecret": "<client secret value>",
    "granttype": "client_credentials",
    "tokenendpoint": "https://<tenant>.authentication.<region>.hana.ondemand.com/oauth/token"
   },
   "protocol": [
    "mqtt311ws"
   ],
   "uri": "wss://enterprise-messaging-messaging-gateway.cfapps.<region>.hana.ondemand.com/protocols/mqtt311ws"
  },
  {
   "broker": {
    "type": "saprestmgw"
   },
   "oa2": {
    "clientid": "<client id value>",,
    "clientsecret": "<client secret value>",,
    "granttype": "client_credentials",
    "tokenendpoint": "https://<tenant>.authentication.<region>.hana.ondemand.com/oauth/token"
   },
   "protocol": [
    "httprest"
   ],
   "uri": "https://enterprise-messaging-pubsub.cfapps.<region>.hana.ondemand.com"
  }
 ],
 "namespace": "sap/scp/em1",
 "serviceinstanceid": "7dbde612-2898-4001-a868-2f1ff8cbb03c",
 "xsappname": "default-7dbde612-2898-4001-a868-2f1ff8cbb03c-clone!b57|xbem-service-broker-!b25"
}
    

 

In the information above, you can find three types of access information, AMQP, MQTT, and HTTP REST. In particular, MQTT is used to connect from S/4HANA, so let’s take a note of the MQTT information.

• URI
• Client ID
• Client Secret
• Token Endpoint

3.5 Download Certificate File

Access Enterprise Messaging Token Endpoint from the browser and drop the certificate.

From here, let’s try the SAP S/4HANA configuration.

3.6 Importing the certificate

t-code STRUST

 

 

 

 

Double click SSL client SSL Client (Standard)

 

 

Import the file downloaded in 3.3

In t-coe SMICM, restart the (ICM) server alone or restart the entire ABAP system.

 

3.7 Move to channel related settings

T-code SPRO “SAP Reference IMG”

SAP NetWeaver-> Enterprise Event Enablement->Administration->Channel Connection Settings

3.8 HTTP Destination Creation

Select “Manage RFC Destination” to create an HTTP destination

Click “Create” button to create a new HTTP destination (connection information to SAP Cloud Platform Enterprise Messaging).

Connection Type should be “G” (HTTP Connection to external server).

Enter the host name (without “wss:///”) and the path using the ” uri ” of the Service Key information above .

In Logon and Security Tab, change the SSL setting to be Active and select the DEFAULT SSL Client(Standard) where the certificates were imported in t-code STRUST.

3.9 OAuth Client Setup

OAuth Client Credential Flow is used for authentication from SAP S/4HANA to Enterprise Messaging and we will create the OAuth client setting.
Click “Manage OAuth 2.0 Account Client Setup”

 

A new browser window will open, enter your user ID and password to log in to the system.

Once you are logged in, press “Create”.

Select “/IWXBE/MGW_MQTT” for the profile and enter the Configuration name freely.
Enter the clientid of the Service Key to the OAuth 2.0 Client ID and press OK.

Set Client Secret (clientsecret in the service key).

For the authorization endpoint replace “token” of token endpoint with “authorize”
Please do not enter “https://” as it is already there

Select “Header Field” and “Client Certificate”

Press “Save”.

 

3.10 Channel Creation

Click “Manage Channel and Parameters”

 

Press “New entries” to add a new entry and enter the Channel Name, Destination name, Topic space and description.
Channel Name: Arbitrary value
Protocol: MQTT_311_WS
Destination: HTTP destination created in 3.8
Topic space: This needs to match to the Enterprise Messaging Namespace.

Select the entry and double-click “Parameters”.

 

Press “New Entries” and add the parameters.

Enter the name entered in 3.9 above for OAUTH_20_CONFIGURATION.

Enter a fixed value of /IWXBE/MGW_MQTT for OAUTH_20_CLIENT_PROFILE.

You can add some other parameters based on the requirements.

Press this button to switch it to display mode.

Click “Active<->Inactive” to activate it.

 

3.11 Check the service settings

 

 

 

 

 

 

 

 

 

 

 

 

Make sure there is an entry for Service: IWXBE, Enablement Service Registry: CL_BEH_SERVICE.

3.12 Event topic setting

Select “Maintain Event Topic”.

 

 

 

 

 

 

 

 

 

 

 

 

Enter the channel name created in 3.10 and press enter.

Enter a new entry for Business Object Event.

If you enter “BO/OutboundDelivery/*” as shown below, all events (create, change, delete) of Outbound Delivery Document will be captured.

 

From here you work with SAP Cloud Platform Cockpit.

3.13 SAP Cloud Platform Enterprise Messaging Subscription

Select subaccount and select “Subscription” from the menu.

Click “Go to Application”.

 

On the Enterprise Messaging Admin page, click Message Client.

You can see the service instance created with CF CLI before.

Select “Create Queue”.

Create it with any name.

The Queue created here is the setting of this red frame part in the figure below.

 

Next, make a subscription from Queue to Topic.

Click “Action” and select #Queue Subscriptions”.

T

 

 

 

 

 

 

 

 

As I have configured in the S/4HANA side, we want to subscribe to the Topic for the Outbound Delivery Document this time. “*” means  all of “create”, “change” and “delete” event again.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

With this setting, the Queue is now subscribing to the Topic, and messages entering the Topic will come to the Queue.
This configuration is the connection part inside the red frame in the figure below.

 

If you want to make an HTTP request to the outside when a message enters the Queue, you can also create a webhook. This setting is not necessary when sending with AMQP.

Let’s create another Queue and set the webhook.
Go to the Webhooks tab and press “Create Webhook”.

Create it by giving the subscription name and entering the destination URL.

 

 

 

 

 

 

 

 

 

 

 

 

Since it is in the paused status at the first creation, select the “Resume” button from the drop-down list to resume it.

 

 

3 .Receiving system side settings etc.

I will omit the details of the setting to receive Queue with AMQP over websocket, but let’s highlight the screenshot here.

Here is the trigger settings in SAP Cloud Platform Extension Factory, Serverless Runtime

Add using the set Queue name.

Connect using the service key information.

This is the sample code for receiving data from Enterprise Messaging.
Java
https://github.com/SAP-samples/enterprise-messaging-client-java-samples
Node
https://github.com/SAP-samples/enterprise-messaging-client-nodejs-samples

4 Conclusion

It is getting more important to think about asynchronous messaging using Event for the future system architecture.This blog is about S/4HANA On-Premise and SAP Cloud Platform but similar concept will come to the other solutions as well. I hope everyone can get the rough idea how the event based messaging works.
And please give it a try!

Enterprise Messaging Developer Tutorial
https://developers.sap.com/tutorial-navigator.html?tag=products:technology-platform/sap-cloud-platform/sap-cloud-platform-enterprise-messaging

S/4HANA On-Premise Enterprise Event Enablement Online Help
https://help.sap.com/viewer/810dfd34f2cc4f39aa8d946b5204fd9c/1909.002/en-US/c200f98fadb64ff1828ed5696c86fca2.html

SAP Cloud Platform Enterprise Messaging Online Help
https://help.sap.com/viewer/product/SAP_ENTERPRISE_MESSAGING/Cloud/en-US

SAP Cloud Platform Extension Factory Serverless Runtime Online Help
https://help.sap.com/viewer/product/XF_SERVERLESS_RUNTIME/Cloud/en-US

SAP Cloud Platform Integration Online Help
https://help.sap.com/viewer/product/CLOUD_INTEGRATION/Cloud/en-US