Name: Implementing a Serverless Function in SAP BTP Kyma Runtime
Uploaded: 2023-12-19
Duration: 387 s
Description: Learn how to implement serverless functions in SAP Kyma Runtime. The second video of the play list explains how to create and maintain serverless functions, configure namespaces, set up environment variables, and create subscriptions.

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<div><div><div>Learn how to implement serverless functions in SAP Kyma Runtime. The second video of the play list explains how to create and maintain serverless functions, configure namespaces, set up environment variables, and create subscriptions.<br><br><br></div></div></div>

Implementing a Serverless Function in SAP BTP Kyma Runtime

In this video of the playlist, the serverless function is implemented in SAP KEMA Runtime. You will learn how to maintain serverless functions and their environment in SAP KEMA Runtime and the logic of the serverless function will be explained. We start in the Cluster Details screen of the KEMA dashboard and select the Applications entry of the menu. Under Applications, we can see which applications are connected to the SAP KEMA Runtime instance. By clicking on our registered application, we can see the details. We can see that APIs and events have been registered. For the APIs, the central gateway URL is provided. This URL is used in the serverless function to access the APIs of the SAP Sales Cloud system via the secured integration. Next, we go to the Namespaces menu entry to create a namespace for our serverless function. Namespaces are used to organize developments in SAP Kima Runtime and to allocate resources. We click on Create Namespace to create a new namespace. In the form, we use the Simple tab and fill in the name of the namespace, adhering to the naming convention. Also, we enable Sidecar Injection to allow the access to the SAP Sales Cloud system. With saving, the new namespace is automatically opened in the overview screen. First, we take a look at the configuration menu and here at the entry Secrets. In the Secrets entry, authentication information and other sensitive data can be maintained and then accessed in a secure way in the serverless function. As we are accessing APIs of a S4HANA cloud system, system, the authentication data including the access URL is stored in this area. Next we go to the functions menu entry in the workloads section. Here serverless functions are maintained. We create a new function by entering a name adhering to the naming convention. Then we select the development language. For the development language Python and JavaScript are available. For our function we select JavaScript with the runtime node.js 18. We keep the function profile XS. For larger functions the resource allocation can be changed easily. With the tab advanced more options are available and in the tab YAML the definition of the function is displayed in YAML and can be edited. By clicking create the function is created. Before we implement the function itself we set environment variables to manage values in a central place that can change when the function is transported to another environment. We add the central gateway URL from the registered SAP Sales Cloud system. Also, we add references to the SAP S4HANA Cloud Authentication credentials that are maintained in the Secrets area. Next, we add dependencies to allow access to additional libraries. In our case, we need access to the Axios library to access the APIs of SAP Sales Cloud and SAP S4 HANA Cloud. In the source area, we now maintain the coding for our serverless function. We remove the sample source code and start with adding constants to reference the Axios library and the central gateway URL maintained in the environment section. Next, we add a module, and in the module a function main, that provides the event it is triggered by as a parameter. From the event, the UUID of the SAP Sales Cloud quote is extracted, and the function C4CReadQuote is called to read the quote from the SAP Sales Cloud API. The function returns the values from the quote in a structure, and the processing type code, which is the document type, is extracted. The quote type is checked to only update quotes of the document type zkag, and then the quote item is read in a functional call and the product ID extracted from the return structure. With the product ID, the plant of the product and the country of origin are read via function calls. For debugging purposes, the country of origin is written into the log. The quote item is updated with the country of origin in a function call. The response from the update is written into the log and as a last step, the return code is returned by the main function to complete the event processing. Next, we take a look at the functions that are called by the main function. First, the function to read the quote from SAP Sales Cloud. The API access is handled by the Axios library, as parameters we hand over the method GET, the URL as a concatenation of the base URL retrieved from the environment variable, and the selection parameters. In case of an error, an entry is written into the log. The function to update the quote item works in a similar way, only that we use the method patch and hand over the structure with the fields to be updated. The functions to access SAP S4HANA Cloud work similarly, but here we need to also hand over the header parameter authorization with the encoded credentials that are retrieved from the environment variables. After implementing the function, we need to create a subscription to the event that is sent by SAP Sales Cloud when a quote is created. This is done in the Configuration section of the subscription entry. Click on Create subscription to add a subscription. Enter a meaningful name, the event name from SAP Sales Cloud, Select the service from the list and select the name of the SAP BTP system landscape entry of the SAP Sales Cloud system for the source. Click on Create to finalize the creation of the subscription. This concludes this video. In the next video you will see a demo of the function and how to access the log of the function.