Receive Alerts in Your On-Premise System Using Java Web Tomcat 9

Download the project as a ZIP file from https://github.com/SAP/cloud-sample-webhooks and extract the files into a local folder.

Open the Command prompt and go to the project's local folder cloud-sample-webhooks-main.

Run the command mvn clean install to compile, test, and package the cloud-sample-webhooks-main project.

You can now find your packaged webhooks.cloud.to.onpremise-1.0.0-SNAPSHOT.war file in the target folder.

Deploy the file on Java Web Tomcat 9 runtime and then start the application. For more information, see Deploying Applications.

The webhooks application is protected with OAuth. For more information, see Register an OAuth Client.

You also need to select the Client Credentials authorization grant.

You need the access token to call the Alerting Channels REST API. For more information, see Using Platform APIs.

Select Monitoring Service API and make sure that the Manage Alerting Channels scope is included.

Create a POST request with one of the following URIs:

• Account level: https://api.{host}/alerting/v2/channels/accounts/{subaccountName}/types/webhook
• Application level: https://api.{host}/alerting/v2/channels//accounts/{subaccountName}/apps/{appName}/types/webhook

The application parameter in the URI is optional, and you do not specify it for alerts on account level.

Use the following code in the body of the Alerting Channels REST call:

{
                    "url": "application_URL/webhook",
                    "authentication": {
                        "authenticationType": "oauth2",
                        "client": "registered_client_ID",
                        "secret": "registered_client_secret",
                        "oAuthServerUrl": "token_endpoint_URL?grant_type=client_credentials"
                      }
}

• Replace application_URL with the webhook application URL. You can find it in the SAP BTP cockpit when you select the deployed webhook application.

• Replace registered_client_ID and registered_client_secret with the client ID and secret created when registering the OAuth client for the webhook application.

These are not the client ID and secret that you created for the platform API.

• Replace token_endpoint_URL with the URL shown for the subaccount at Security > OAuth > Branding > Token Endpoint in the SAP BTP cockpit.

Furthermore, use the access token as a bearer token in the Authorization for the REST API call.

For more information, see Alerting Channels REST API.

Select the application in the SAP BTP cockpit, choose the Update button, and enter the verification token as a JVM argument (-DverificationToken=<verification_token>).

Finally, restart the application for your change to take effect.

Use Java Web Tomcat 9 server and deploy the WAR file locally. See Deploy Locally with the Console Client.

1. Start the cloud connector.

> After you have configured the Cloud Connector as mentioned in **Prerequisites**, make sure that it connects to the internal system by using ![Check availability of internal host](https://raw.githubusercontent.com/sap-tutorials/btp-foundation/main/tutorials/cp-monitoring-alerts-onpremise/Check_Availabiltity_Internal_Host.png).

2. Configure the access control.

Go to the **Cloud to On-Premise** view and add the resource `/webhooks.cloud.to.onpremise-1.0.0-SNAPSHOT/backend`.

![Resource mapping](https://raw.githubusercontent.com/sap-tutorials/btp-foundation/main/tutorials/cp-monitoring-alerts-onpremise/Add_Resource.PNG)

1. Log on to the SAP BTP cockpit.

2. Select the subaccount.

3. Go to Connectivity > Destinations.

4. Create a new destination with the following values:

|Field Name    |Value                                                                                    |
|:-------------|:----------------------------------------------------------------------------------------|
|Name          |`on-premise-destination`                                                                 |
|Type          |`HTTP`                                                                                   |
|URL           |`http://<virtual host>:<virtual port>/webhooks.cloud.to.onpremise-1.0.0-SNAPSHOT/backend`|
|Proxy Type    |`OnPremise`                                                                              |
|Authentication|`NoAuthentication`                                                                       |

For more information, see [Configure the Destination in the Cloud](https://help.sap.com/viewer/b865ed651e414196b39f8922db2122c7/Cloud/en-US/e76f9e75bb571014a7218bcd30a8771b.html#loioe76f9e75bb571014a7218bcd30a8771b__configure_destination_cloud).

> The virtual host and port are configured in the cloud connector under **Cloud To On-Premise** > **Access Control** > **Mapping Virtual to Internal System**.

5. Check that the connection to the on-premise destination is successful.

Trigger an alert by setting low threshold values (for example, Warning Threshold = 0.00001 and Critical Threshold = 0.0001 for the availability check of the application). You should receive the alert as an alert_<timestamp>.json file locally in the server’s workspace folder (usually in the …/webapps/webhooks.cloud.to.onpremise-1.0.0-SNAPSHOT folder).