SAP® Netweaver Gateway - Basics, Architecture and CRUD oData

CRUDQ is an acronym given to basic operation which is done by services which means Create, Read, Update, Delete and Query, they are most fundamental operations which a developer implements by ABAP code in Gateway.

We will go into details about what CRUDQ stands for and present the example which we will be build in the consecutive sections.

In this section we will start from scratch and implement the method GET_ENTITYSET which will allow us to do query operation in our table from web browser.

Each part is covered in step by step manner and in detail.

*Also see the resource section for code link.

You will see how we can perform read operation with services, where we will try to read a single record from SAP Table by passing a key parameter in our URL .According to this key parameter we will see the result .

*Also see the resource section for code link.

In this part we will go through how to add new records to our SAP Table, the demonstration will be shown in the Gateway client where we will use the POST method to pass data to our services.

*Also see the resource section for code link

Once we have added any record in the SAP Tables we can also update the values to new values and we will see how update operation is performed in the Gateway client where we will use the PUT method.

For this we also have to provide the key field from where we need to update the value and the new values as well.

*Also see the recource section for code link

In this section you will see how to perform the delete operation of the table many a times for standard operation BADI's will be provided by SAP so developer need to call that instead of doing manual delete as this is a custom data structure we created, there is no BADI available so we are calling the native SQL syntaxes in ABAP.

*Also see the recource section for code link

You will see how from SAP UI5 App, we have implemented the CRUD operation and we will do the code walk through to understand how the App is designed and developed.

Even if you are seeing UI5 App for first time you will come to know where and how front end developer will be doing the operation to integrate with SAP backend system.

Security involved in gateway will also be shown which will be using default SSO.

*Also see the resource section for code link

You will see how our UI5 App is doing the delete, create and update operation where key and data values are passed to Gateway system.

The oData methods provided by UI5 library will be explained in details with the callback functions on success and failure of the operation.

*Also see the resource section for code link

You will come to know how to push the UI5 code inside SAP and show you how to launch the app from inside SAP.

If your Gateway system exist within same SAP ERP then you will have the webserver which is hosting UI5 App and Gateway calls implemented with ERP data in a single machine which is called embedded model.

But the standard approach is to have Gateway in separate system from ERP, where the app will be hosted by Gateway with services present inside it and Gateway will be doing RFC calls to SAP ERP system for data and this model is called HUB model.

The overall usecase which we have considered involves the following communication sequence:

Sensor->Arduino->Raspberry Pi->Internet->SAP HANA XSJS->SAP HANA DB->SAP UI5 Application

Raspberry Pi will be sending data to SAP HANA by invoking SAP XSJS script and providing data in request parameter.

The data is stored in a table where we are going to store the sensor ID, timestamp and the sensor value.

SAPUI5 application will be reading recent data using polling mechanism.

In order to keep the development process simple to understand we have not provided a security key validation during sensor reading insertion into HANA DB.

And also we have not considered the timestamp when the data is inserted in the database so we could avoid the timestamp conversion steps.

SAPUI5 application will have two tiles: one to show near real time sensor values and another as a comparator.

Note: In real life IoT project these two things should be included. We can also use push notification instead of polling which is a better alternative in real IoT world projects.

We are going to create the following files:

DemoSchema.hdbschema: For linking the DemoSchema to the project.

SensorNetwork.hbdd: For our Data Definition.

insert_sensors_reading.hdbprocedure: For inserting sensor data to HANA database.

sensor_read.hdbprocedure: For reading recent sensor data from HANA database.

getSensorReading.xsjs: For passing recent sensor data to SAPUI5 application.

putSensorReading.xsjs: For allowing Raspberry Pi to insert sensor reading to SAP HANA database.

.xsaccess and anonymous_access.xssqlcc: For providing anonymous access to HANA Database .

We need to configure the anonymous access by going into HANA admin panel using URL:

https://<ip:host>/sap/hana/xs/admin/

We need to download Eclipse Kepler and install SAP HANA plugins from this repository https://tools.hana.ondemand.com/kepler/

We need to copy the program present in the powerpoint to the corresponding files.

Special attention: make changes in the code if you are going to use a different package structure. In this case, you need to replace all the occurrences of demoApp.demo01.app02.SHIOT_02 with your HANA project package path.

.hdbschema is a design-time definition of a database schema, which organizes database objects into groups.

This database schema enables you to create and activate application artifacts such as tables, views and database procedures. Without a defined schema, database objects cannot be generated in the SAP HANA catalog upon activation of specific design-time artifacts that are added to the SAP HANA repository.

SAP HANA repository: The SAP HANA repository is the central component of the SAP HANA development infrastructure and an integral part of the SAP HANA system. The repository is used for central storage and versioning of software artifacts, and it is also the foundation for lifecycle management for SAP HANA content and for the translation of SAP HANA applications. The repository provides the export and import functions needed for shipping applications to customers and for transporting development results between SAP HANA systems.

The XSJS file are using $.request.parameters.get() function to read data from the URL and $.response.contentType, $.response.status and $.response.setBody() variables and function respectively to set the response of the XSJS script.

HANA database procedures are called by the XSJS script using conn.prepareCall() function which takes a parameter called query that corresponds to our stored procedure call statement with appropriate parameter set using setString() and setInteger() integer.

On successful reading of the record we will get a record of demo02sensor_active_TS which is storing sensor Transactional Data in our HANA Database.

On successful insertion of a new record in demo02sensor_active_TS table we get zero number of the record in the database.

Having exception handling in XSJS script is useful as it can give you a quick feedback in case of errors.

Given an overview of the architecture and concepts of SAPUI5

SAPUI5 is a client UI technology based on JavaScript, CSS and HTML5. SAPUI5 applications run in a browser. Depending on the device the application is to run on (mobile, tablet or desktop PC), you use different UI libraries.

In the Model View Controller concept, the representation of information is separated from the user's interaction:

• The view is responsible for defining and rendering the UI.
• The model manages the application data.
• The controller reacts to view events and user interaction by modifying the view and model.

As SAPUI5 is a client-side web UI library meaning that it runs in a browser, a SAPUI5 application typically is composed of an HTML page and, if required, many more files.

To create a SAPUI5 Application Project, you must have installed the SAPUI5 Application Development feature in your Eclipse installation.

As SAPUI5 is a client-side web UI library meaning that it runs in a browser, a SAPUI5 application typically is composed of an HTML page and, if required, many more files.

SAPUI5 is implemented in JavaScript. For loading SAPUI5, its bootstrap needs to be included with a <script> tag. The last two attributes select the visual design to apply initially (other choices would be sap_hcb or sap_goldreflection) and the SAPUI5 control library/libraries to use . In your scenario you need to make sure the URL points to a SAPUI5 installation.

<script id="sap-ui-bootstrap"

src="resources/sap-ui-core.js"

data-sap-ui-theme="sap_bluecrystal"

SAP UI5 project for this project is very simple and contains only one Controller SHIOT_UI_02.controller.js and a view SHIOT_UI_02.view.js.

View:

View is using sap.suite.ui.commons.GenericTile and placing them in tile container sap.suite.ui.commons.TileContent which is added to the content section of the sap.m.Page.

setInterval() is responsible for the polling mechanism in the View which will run the changeKPITest function of the controller every 3 sec.

Controller :

changeKPITest() is responsible for calling XSJS script using AJAX and updating the SAPUI5 model which is bound to the tiles. It is also changing the small color window background CSS relative to sensor measurement.

The development code can be found in the powerpoint provided in the resource section or UI5CN blog.

SAP UI5 application need to be linked to our previously build SAP HANA project .