## 5.6.2.3.2.3  Define SAP S/4HANA Cloud Extensibility Service Descriptor JSON/YAML File
The SAP S/4HANA Cloud Extensibility service descriptor defines details of a message client and needs to be provided when provisioning new SAP S/4HANA Cloud Extensibility service instances with service plan messaging .
## Procedure
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Define the SAP S/4HANA Cloud Extensibility service descriptor in a JSON structure for the Cloud Foundry environment and in a YAML structure for the Kyma environment. It has to contain two sections:
- For the parameters needed to activate the communication arrangement for the communication scenario Enterprise Eventing Integration (SAP\_COM\_0092) in the SAP S/4 HANA Cloud tenant. There are only two required parameters, emClientId and systemName . The rest of the parameters are automatically generated. However, you can still provide the optional parameters in the descriptor to override the automatically generated values.
- For the parameters for configuring the SAP Event Mesh service. If this section is not explicitly added to the JSON/YAML file, the values of its parameters are automatically generated based on the values of the emClientId and systemName parameters.
Parameters required to activate the communication arrangement in SAP S4/HANA Cloud tenant
| Parameter                | Description                                                                                                                                                                                                                                                                                         |
|--------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| systemName               | The name of the system you have registered in the global account in SAP BTP. Rules/Guidelines • Required: Yes • The name must be the same as the one you have used when registering the SAP S/4HANA Cloud system dur- ing the pairing process.                                                      |
| emClientId               | Using default patterns, it generates communication ar- rangement name , channel name , emname , and name- space , when these parameters are not explicitly provided. The default values are described in the table bellow contain- ing the parameters required to configure SAP Event Mesh service. |
|                          |  Note The values of the emname and namespace parameters must be the same as the values of the emname and namespace parametes in the SAP Event Mesh service descriptor. See Define SAP Event Mesh Service Descrip- tor JSON/YAML File [page 2158].                                                  |
|                          | Rules/Guidelines • Required: Yes • Allowed characters: [a-zA-Z0-9] • Maximum length: 4                                                                                                                                                                                                              |
| communicationArrangement | Defines the communication arrangement for the SAP S4/ HANACloud tenant.                                                                                                                                                                                                                             |
## Parameter
## Description
| communicationArrangementName   | A communicationArrangement property. The name of the communication arrangement for the SAP S/4HANA Cloud tenant. Rules/Guidelines • Required: No • Allowed characters: [a-zA-Z0-9_-] • Maximum length: 80 • Default value: "SAP_CLOUD_PLATFORM_XF_<emClientId>"                                                                    |
|--------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| attributes                     | A communicationArrangement property. Defines the configuration properties for the communication arrangement. The name of the property is equivalent to the Technical Property Name column in the properties table in the Display Communication Scenarios app in the SAP S/4HANA Cloud system. See Display Communication Scenarios. |
| CHANNEL NAME                   | An attributes property. The name of the communication channel. Rules/Guidelines • Required: No • Allowed characters: [A-Z0-9_-] • Default value: "SAP_CP_XF_<emclientId>"  Note Have in mind that the <emclientId> will be au- tomatically capitalized. • Must be unique within the SAP S/4 HANACloud tenant.                     |
## Parameter
## Description
| DESCRIPTION   | An attributes property. Short description. Rules/Guidelines • Required: No • Maximum length: 60 • Allowed characters: [a-zA-Z0-9_-] • Default value: "Integration with Enterprise Messaging for EM Client: <emclientId>"                                                                                                                                                                                                                                                                                                      |
|---------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| TOPIC SPACE   | An attributes property. The identifier for the events that originate from the same source. This is the topic that the events should use. Rules/Guidelines • Required: No • Maximum length: 24 • Allowed characters: [a-zA-Z0-9/ /] • Contains exactly three segments, for example a/b/c . • Default value: "sap/S4HANAOD/<emclientId>" • The subscribeFilter in the SAP Event Mesh con- figuration must be use the topic space as a prefix.                                                                                   |
| MQTT_QOS      | An attributes property. Defines the quality of service. Rules/Guidelines • Required: No • Allowed values: 0 , 1 QoS= 0 , at most once delivery. The message is delivered according to the capabilities of the underlying network. No response is sent by the receiver and no retry is performed by the sender. The message arrives at SAP Event Mesh either once or not at all. QoS= 1 , at least once delivery. This quality of service ensures that the message arrives at SAP Event Mesh at least once. • Default value: 1 |
| Parameter                                               | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| RECONNECT ATTEMPTS                                      | An attributes property. The number of attempts the Enterprise Event Enablement framework tries to reestablish the connection if the connec- tion is lost. Rules/Guidelines • Required: No • Default value: 0 • If no value is entered or the entered value is 0, the framework tries to connect until connection is estab- lished. If the connection is not established after reach- ing reconnect attempts, the communication arrange- ment and the underlying channel is deactivated. |
| WAIT TIME                                               | An attributes property. Specifies the time (in seconds) for which the Enterprise Event Enablement framework waits before trying to recon- nect. If the attempts fail, framework increases the wait time until the reconnect wait time (1800 seconds) is reached. Rules/Guidelines • Required: No • Default value: 10                                                                                                                                                                    |
| Parameters required to configure SAP Event Mesh service |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Parameter                                               | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| emname                                                  | Specifies the name of the SAP Event Mesh client. It is used by SAP Event Mesh to identify clients. Rules/Guidelines: • Required: No • Allowed characters: [a-zA-Z0-9_-] • Maximum length: 100 • Default value: <emClientId> • It is unique within a subaccount.                                                                                                                                                                                                                         |
| Parameter     | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|---------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| namespace     | Namespace for the message client. Rules/Guidelines: The namespace in the SAP Event Mesh configuration must be the same as the first three segments of the topic space in the configuration of the communication arrangement in SAP S4/HANA Cloud tenant. Rules/Guidelines: • Required: No • Allowed characters: [a-zA-Z0-9//] • Maximum length: 24 • It is unique within a subaccount • Contains exactly three segments, for example a/b/c . • Default value: "sap/S4HANAOD/<emclientId>" . |
| rules         | Defines the access privileges of the message client. Guidelines/Rules: • Required: No • In order to allow access to a queue or a topic the namespace of the corresponding owner client has to be added. The placeholder ${namespace} can be used instead of the defined namespace.                                                                                                                                                                                                          |
| topicRules    | A rules attribute. Guidelines/Rules: • Type: object                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| inboundFilter | A topicRules attribute. Defines if a client (publisher/producer) is allowed to send messages to the defined topics. Guidelines/Rules:                                                                                                                                                                                                                                                                                                                                                       |
## Parameter
resources units
## JSON File Example
In this example, only the required properties are provided.
```
"systemName": "DEV", "emClientId": "s4hc"
```
```
{ }
```
This descriptor is equivalent to:
##  Note
All properties can be overridden explicitly.
```
{ "systemName": "DEV", "emClientId": "s4hc", "communicationArrangement": { "communicationArrangementName": "SAP_CLOUD_PLATFORM_XF_s4hc", "attributes": [ { "name": "CHANNEL NAME", "value": "SAP_CP_XF_S4HC" }, { "name": "DESCRIPTION", "value": "Integration with Enterprise Messaging for EM Client: s4hc" }, { "name": "TOPIC SPACE", "value": "sap/S4HANAOD/s4hc" },
```
## Description
A collection of messaging resources such as queues, connections, and so on, required for a message client.
## Rules/Guidelines
- Required: No
A resources attribute.
Specify this value in the service descriptor to allocate messaging resources based a specific business scenario. See Syntax for Service Descriptor.
## Guidelines/Rules:
- Required: No
- Allowed values: 10-50
- Type: attribute
- Default value: 10
```
{ "name": "MQTT_QOS", "value": "1" }, { "name": "RECONNECT ATTEMPTS", "value": "0" }, { "name": "WAIT TIME", "value": "10" } ] }, "ems": { "parameters": { "emname": "s4hc", "namespace": "sap/S4HANAOD/s4hc", "rules": { "topicRules": { "inboundFilter": [ "${namespace}/#" ] } }, "resources": { "units": "10" } } } }
```
## YAML File Example
In this example, only the required properties are provided.
```
parameters: systemName: DEV emClientId: s4hc
```
This descriptor is equivalent to:
##  Note
All properties can be overridden explicitly.
```
spec: externalName: '' serviceOfferingName: s4-hana-cloud servicePlanName: messaging parameters: systemName: DEV emClientId: s4hc communicationArrangement: communicationArrangementName: SAP_CLOUD_PLATFORM_XF_s4hc attributes: - name: CHANNEL NAME value: SAP_CP_XF_S4HC - name: DESCRIPTION
```
```
value: 'Integration with Enterprise Messaging for EM Client: s4hc' - name: TOPIC SPACE value: sap/S4HANAOD/s4hc - name: MQTT_QOS value: '1' - name: RECONNECT ATTEMPTS value: '0' - name: WAIT TIME value: '10' ems: parameters: emname: s4hc namespace: sap/S4HANAOD/s4hc rules: topicRules: inboundFilter: - "${namespace}/#" resources: units: '10'
```