Prerequisites:

You have SAP Integration Suite, and you have activated Event Mesh as a capability.

Creation of a Queue on EMIS

Creation of a topic subscription

Next, create a topic subscription.

For S4 integration, it is important to note that the topic name should correspond to the topic space defined in S4. Kindly note the asterisk (*) in the topic name which acts as a wildcard for the topic hierarchy.

Creation of a service key for EM messaging client

The service key is needed to get the credentials for S4 to connect to EMIS.

Kindly create the service key post successful creation of service instance.

Creation of SM59 destination on S/4

S/4HANA needs details such as hostname and port to connect to EMIS. These details are specified in the sm59 destination.

Kindly execute the following transaction:

/nsm59

Choose ‘Create’

Provide a destination name and choose connection type as ‘HTTP connection to external server’

Save.

Now, refer to the service key created using SAP Integration Suite, Event Mesh – ‘message client’ instance.

You need to refer to this service key to provide the details in the sm59 destination.

The hostname can be obtained from the ‘uri’ section under ‘messaging’

The port should be ‘443’ and path prefix ‘/protocols/amqp10ws’ for AMQP. (the first release of EMIS only supports AMQP protocol for messaging)

In the logon and security tab, set ‘SSL’ to ‘Active’ as shown below –

Save.

Creation of Oauth client for S4

S4HANA authenticates with EMIS using Oauth2.0.

You need to execute the below transaction:

/nOA2C_CONFIG

Choose ‘Create’ and provide the necessary details.

The OAuth2.0 Client Profile as shown above needs to be ‘IWXBE/MGW_MQTT’ even for AMQP based messaging.

You can provide any configuration name, the Oauth 2.0 client ID can be found from the service key created above under the ‘oa2’ section in ‘messaging’.

Choose OK.

Provide the client secret, authorization and token endpoint from the service key.

The authorization endpoint is not directly provided in the service key, but it is same as the token endpoint, except that it ends with ‘/authorize’ as show below.

The Access Settings are mentioned below:

Client Authentication: Form Fields

Resource Access Authentication: Header Field

Selected Grant Type: Client Credentials

Creation of a channel using form fields on S/4

Kindly execute the below transaction to configure the channel:

/n/IWXBE/CONFIG

Create a new channel (without service key).

At this point, it is not possible to configure this using the ‘Create Channel via Service Key’ option.

This is currently a gap and will be addressed in an upcoming release.

It is important to note that the above gap is only applicable for Event Mesh in Integration Suite (EMIS).

For Event Mesh (default), the recommended way is to use ‘Create Channel via Service Key’ option on S4.

Choose ‘Default’ or ‘SAP Event Mesh’.

Now the following details need to be provided –

You can provide any name to the channel.

The destination needs to be the name of the sm59 destination as created above.

The topic space needs to correspond to the topic subscription on the Queue.

The Oauth 2.0 Configuration needs to be the name of the Oauth2.0 client configuration as created above.

Save.

Activation of Channel & Connectivity Check

Click on ‘Activate’ followed by ‘Check Connection’ to ensure that connection to Event Mesh is successful.

Sending a Test Event using Event monitor

Kindly execute this transaction,

/n/IWXBE/EEE_SUPPORT

Choose ‘Produce Test Events’ followed by the channel.

Execute the transaction.

You can now navigate back to Event Mesh in Integration Suite, head over to the Queues section and find the message queued! (unless there is active consumer)

Congratulations – You have succeeded in integrating SAP S/4HANA with Event Mesh in Integration Suite!

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What is Event Mesh?

SAP Event Mesh allows applications to communicate through asynchronous events. Experience greater agility and scalability when you create responsive applications that work independently and participate in event-driven business processes across your business ecosystem. In this decoupled integration the producers of the events will not know the consumers of the events.

Publish business events from SAP and non-SAP sources across hybrid landscapes from the digital core to extension applications through event-driven architecture. Consume business events from SAP and non-SAP sources throughout SAP’s event-driven ecosystem including SAP Extension Suite, SAP Integration Suite, and selected inbound enabled SAP backends. Achieve reliable data transmission for extension and integration scenarios through decoupled communication.

What is Websocket?

WebSocket is a stateful protocol used in the client-server communications used to enable the application you are using to receive the data without requesting it from the server like two-way communication. It means the connection between client and server will keep alive until it is terminated by either party (client or server). Data is sent and received much faster than HTTP as HTTP has a 2000-byte overhead whereas WebSocket has only a 2-byte cost. WebSockets supports multiple data types. In SAP CI AMQP adapter supports the websocket transport protocol.

What is Webhook?

Webhooks are stateless, meaning that each event notification is independent and carries all the necessary information about the event. Webhooks are for server to server communication. Web-hooks are commonly used to perform smaller requests and tasks on top of standard API calls. Webhooks are suitable for POST/PUSH mechanism. In the Event Driven Architecture when the Producer publish the events to the respective topics, then the Queues subscribed to those topics will trigger the event data to the consumer using the Webhook instead of consumer trying to pull the events.

What is Queue?

A queue is used to store a message until it’s received by the subscribed consumer. Queue cannot process message, it is first consumer and just store message/event. If any events are published in the Queue then only one subscriber to that Queue received a message. Queues are managed and persistent. When there are no consumers to a queue, messages are stored in the queue.

What is Topic?

Topics are not managed and not persistent. A topic is created on the go when we start publishing messages to a topic, and destroyed when there are no consumers listening to that topic. If the consumer to a topic is not running when a message is published to the topic, that event will not be received. One Event Producer can publish to one Topic. One Topic can be connected to multiple queues. Multiple queues can be subscribed to one topic.

Prerequisites:

1. BTP cockpit access with Event Mesh subscription.
   
2. S4 HANA access in tcodes STRUST and SPRO
   
3. SAP BTP IS Tenant Access with required roles/roles collection having Enterprise Messaging*.

Step-1: Add Service Plans in the Entitlements of subaccount for Event mesh along with creation of instance and subscription.

Select the standard and default service plans for the Event Mesh in the Entitlement

“Standard” for Event Mesh subscription and “default” for instance creation

In the Instances and Subscription, create the “standard” event mesh subscription and “default” instance creation on top of the cloud foundry space and runtime environment.

While creating the service instance creation the Instance Name and EMNAME in JSON file should be same along with the Namespace in required format e.g. a/b/c

Step-2: Creation of Service Key for eminstance created

The clientid, clientsecret,tokenendpoint, protocol and uri should be noted for further configurations

Step-3: Creation of new Queue in Instance of Event Mesh

Step-4: Test publishing and consuming messages on a queue. [Optional]

Select the queuename and message client name for publishing and consuming the messages.

Step-5: Creation of OAuth2 client credentials in Security Material of Integration Suite

Use the TokenEndPoint URL and ClientID and Client Secret from the Event Mesh service Key created.

Step-6: Produce the events from SAP CI into Event Mesh

A new IFlow needs to be created with either HTTPS as sender for triggering from Postman or timer based event with some message in content modifier and AMQP as receiver.

For Demo purpose we will use the HTTPS as sender and AMQP receiver with WebSocket message protocol. Host will be the URI from the service key. Port:443 Path will be the protocol from service key. Credential Name from the security material.

We can publish on topics or the queue from the AMQP(Websocket) of CI.

For topic, topic:topicname(this topicname should be subscribed on the queue created in event mesh) and for queue, queue:queuename

Test from Postman with deployed IFLOW endpoint with the clientid and clientsecret of the Process Integration Runtime service key. This is to understand how the event are published. Not a realtime scenario.

Check the CI Message Monitor for successful message to Event Mesh

Check in the Event Mesh Queue with messages count increased from 0 to 1 along with queue size.

Step-7: Consume the events from Event Mesh into CI

Consuming the events from Event Mesh into CI can be done either with websocket(AMQP) or webhook.

In this case will create a websocket(AMQP) connection by configuring a new IFLOW with HOST, Path from Event Mesh service key, Port:443 and Credential Name from Security Material.

The queue name as queue:queuename. While consuming the Events from CI its always best to consume from queue rather the topic as topic are not persisted and queues are persisted which we can use for guaranteed delivery. As the message will be consume in JSON format we can convert it into XML as required.

Once deployed the message in the queue will be consumed by the CI IFLOW

Step-8: Create Topic and upload the certificate to produce the Events from S4 HANA onto Event Mesh

The overall design for S4 HANA to publish and CI to consume can be done in two ways

A. Websocket Communication

B. Webhook Communication

Websocket is already explained in the previous steps. Will check now the Webhook communication.

On top of the created Queue in Event Mesh we need to subscribe to a Topic

Download the certificate from the Token Endpoint along with clientid and clientsecret generated from the Event Mesh Service Key

Upload the certificate in S4 HANA STRUST in SSL Client SSL Client(Standard) and add to certificate list

Step-9: Create a AMQP Channel in SPRO tcode

Goto SAP Reference IMG=>ABAP Platform=>Enterprise Event Enablement=>Administration=>Channel Connection Settings=>Manage Channel and Parameters

Use the service key option to create the AMQP channel

Check the connection and activate the channel

Step-10: Create outbound binding on the created AMQP channel

Select the created channel and click on outbound binding and provide the topic name.

Step-11: Create webhook in the SAP Event Mesh

In order to create the webhook we need any HTTPs URL to be build and deployed. In our case we will create a new IFLOW with HTTPS as sender in CI itself.

Create a webhook with queue name, CI deloyed IFLOW endpoint and authentication with client id and client secret of the CI Process Integration Runtime

Testing:

Testing the Event from S4 HANA onto Event Mesh which will push through the WEBHOOK on CI.

Goto SAP Reference IMG=>ABAP Platform=>Enterprise Event Enablement=>Test Tools=>Produce Test Events

Select the channel name created and trigger the Event.

Check the CI Monitoring whether the event triggered from S4 HANA to Event Mesh was pushed onto CI through Webhook

Question 1??? What happens for triggered event from S4 HANA(Producer) is published on one topic in Event Mesh and there are both Websocket Queue Consumer to CI and Webhook Queue Consumer to CI with same topic/queue details.(Ideally it will not be the case in realtime but for testing will explore that case here)

Answer!!! As the queue consumer will be in continuous consumption mode it will be more quick to take the message in rather waiting for the webhook to trigger the message to the configured HTTPs endpoint.

Evidence***

The deployed consumer IFLOW is in continuous consumption mode. Also the consumer should be subscribed from Queue instead of Topic for persistence.

Question 2??? What happens when there are some errors(mapping/runtime) during the consumer receiving messages from the Event Mesh Queue? Will the message be deleted from Queue immediately or it will persist till the successful consumption?

Answer!!! The message in the queue will be present till the consumer receives and process it successfully. During that time the consumer will continuously retry.

Evidence***

When the consumer IFLOW intentionally failed for some content exception the message in the queue was still persisted and the IFLOW was automatically retried almost 8770 times in less than a minute.

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