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This article focuses on "what are the SAP API development methods", interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn "what are the SAP API development methods?"

(1) ABAP function module + SOAMANAGER

The oldest technology, the functions in the ABAP system are published into Web Service through SOAMANAGER. Although ancient, the development of new features of the Service module in S/4HANA is still in use.

(2) Manual implementation of SAP CRM OData service based on transaction code SEGW

This is the SAP OData service implementation that I am most familiar with, because I am one of the developers of SAP CRM OData services. When the CRM development team of SAP Chengdu Research Institute developed these OData services in 2014 and 2015, the predecessor of SAP Fiori Elements, then called Smart Template, was still in its infancy, so we did not choose this metadata-driven development approach at that time.

(3) automatic generation of OData services based on CDS view

Later, as CDS view and Fiori Elements mature, we can generate OData services directly based on CDS view annotated with @ OData.publish

In S/4HANA, in addition to manually annotating CDS view in ABAP Development Tool with @ OData.publish, there is another way to do this purely in the browser.

Use the Custom CDS Views application in S/4HANA

You can select multiple standard CDS view in S/4HANA to create a new composite view

And can choose which fields of the standard view need to be included in the new composite view according to their own needs:

Finally, it is also an one-click implementation of the composite view of the OData service publication.

On the SAP cloud platform ABAP environment, based on the Service Definition and Service Binding created by CDS view, all the creation of OData services and Fiori UI interfaces are arranged.

(4) Custom OData API creation based on Business Object in SAP Cloud for Customer

The Custom CDS View application seen earlier in SAP S/4HANA Fiori Launchpad can complete the collocation of fields and the release of OData services in the browser, even if it is not very technical Key User.

SAP Cloud for Customer has a similar design, except that the choice for Key User is not CDS view, but the standard Business Object in C4C.

Key User can choose which fields in the Business Object node to publish to the OData service in the browser's Custom OData Service application, which is the same as selecting standard CDS view fields in SAP S/4HANA.

In the Cloud Application Studio of C 4C, you can also create Web Service based on the standard Business Object.

Summary: SAP products based on ABAP technology stack, OData or Web Service API running on it, are essentially consumed by the outside world through ABAP Netweaver's ICF (Internet Communication Framework). By observing its calling Url path, we can find the corresponding processing node in the SICF transaction code.

Take the CRM_OPPORTUNITY at the end of the SAP CRM OData service Url as an example:

The corresponding node with the same name can be found in the SICF transaction code. We only need to bind an ABAP class to this node in SICF, and when the corresponding Url of the node is accessed through a browser or Postman, or other programming language, the ABAP ICF framework will automatically call the bound ABAP class.

In other words, application developers only need to implement business logic in the ABAP class. ABAP developers do not have to worry about how the runtime instance of this class is called by ICF, how to initialize and destroy and other life cycle management.

(5) API development based on Web application framework such as Java SpringBoot,Node Express.

The biosphere which adopts this kind of development method is the largest and most active group in the world, the technology is mature and stable, and the relevant documents and teaching materials are very rich. Newer and more advanced development frameworks are also evolving. Developers usually complete the development locally and then deploy the application to run on the server. You can also package the application as a container image, and then run it on physical servers, SAP cloud platforms, AWS,Google Cloud Platform,Azure and other clouds as containers. After the number of containers reaches a certain scale, Kubernetes can be used for orchestration and management.

SAP Commerce's Web Service was also consumed in previous Jerry projects: how to consume SAP Commerce Cloud's order service using API.

(6) Serverless architecture

A popular word in the cloud computing industry, Serverless architecture, does not mean that the server is no longer needed after adopting this architecture, but that application developers do not have to care about how the developed applications are deployed to the server, and do not need to consider operation and maintenance issues such as the running status of the server. The development idea of traditional Web application, as previously introduced, usually completes the development and unit testing locally, and then needs to consider how to deploy to which server or cloud.

For API/ service development based on Serverless architecture, there is no such step of API deployment at all. Take Lambda Function on SAP Kyma introduced by Jerry as an example, the coding of the API function itself is done on the cloud. Once saved, the API is called as soon as the trigger condition maintained by the API is met (event trigger or Url trigger).

The following is a Lambda Function I wrote in SAP Kyma using nodejs:

I set it to be called via HTTPS:

Access the HTTPS-endpoint,Lambda Function in the browser and execute it immediately.

From this perspective, Jerry feels that ABAP developers, when developing API, have been enjoying the convenience of the Serverless architecture. Because the development of ABAP domain, whether through SAPGUI,ABAP Development Tool or through various Key User tools, is essentially connected to ABAP Netweaver, a server that integrates application development and operation, so there is no application deployment in traditional Java/nodejs development at all.

For more information on how to use Lambda Function to implement API, please refer to Jerry's article:

From SICF in ABAP Netweaver to Lambda Function in SAP Kyma

Zhou Botong's Kongming fist, Minos's Stardust puppet line, SAP Kyma's Serverless

(7) SAP Data Intelligence Graph

Strictly speaking, this approach is also based on Serverless, and users log in to the SAP Data Intelligence console through a browser to model Graph. When it is started, Graph runs directly on SAP Cloud Platform's Kubernetes infrastructure.

The reason for introducing this approach separately is that it also has the characteristics of Low Code Development (low code development).

Look at a specific example.

Suppose I want to implement an API that supports CRUD, where consumers can read, insert, and delete a record in the database through HTTP GET, POST, and DELETE requests.

Low-code development platforms, which usually provide a graphical user interface, provide users with a way to quickly create applications or API by dragging components and model-driven development, combined with a small amount of code.

Visit SAP Data Intelligence Launchpad and enter Modeler:

Like children building blocks, we drag HTTP Server and several JavaScript Handler from the toolbox on the left to the editing page.

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