SAP HANA Interview Questions & Answers Set-5

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1. What are the supported platforms for HANA studio?

Ans: The SAP HANA studio runs on the Eclipse platform 3.6. We can use the SAP HANA studio on the following platforms:
• Microsoft Windows x32 and x64 versions of: Windows XP, Windows Vista, Windows 7
• SUSE Linux Enterprise Server SLES 11: x86 64-bit version
Note: For Mac OS, HANA studio is available but there is no HANA client for that.

2. What are the system requirements for HANA studio?

Ans: Java JRE 1.6 or 1.7 must be installed to run the SAP HANA studio. The Java runtime must be specified in the PATH variable. Make sure to choose the correct Java variant for installation of SAP HANA studio:
• For a 32-bit installation, choose a 32-bit Java variant.
• For a 64-bit installation, choose a 64-bit Java variant.

3. How to add new HANA system in HANA studio?

Ans: In order to connect to a SAP HANA system we need to know the Server Host ID and the Instance Number. Also we need a Username & Password combination to connect to the instance.
The left side Navigator space shows all the HANA system added to the SAP HANA Studio.

Steps to add new HANA system:
1. Right click in the Navigator space and click on Add System


2. Enter HANA system details, i.e. the Hostname & Instance Number and click Next.


3. Enter the database username & password to connect to the SAP HANA database. Click on Next and then Finish.


4. The SAP HANA system now appears in the Navigator.


4. What is the difference between catalog and content?

Ans: In HANA Studio every HANA system has two main sub-nodes, Catalog and Content. 

Catalog:
  • The Catalog represents SAP HANA’s data dictionary, i. e. all data structures, tables, and data which can be used.
  • All the physical tables and views can be found under the Catalog node.
Content:
  • The Content represents the design-time repository which holds all information of data models created with the Modeler.
  • Physically these models are stored in database tables which are also visible under Catalog. The Models are organized in Packages. The Contents node just provides a different view on the same physical data.
  • The created Column Views are always located in schema _SYS_BIC, their metadata in schema _SYS_BI.
5. Does 32 bit version of HANA client work with SAP HANA repository and SAP HANA Development perspective?

Ans: There is no 32 bit version of the repository client. 

If you want to make use of the repository integration features, for example, in the Project Explorer view in the SAP HANA Development perspective, you must install the 64 bit version of the repository client. 

6. How can we set path to the repository client in HANA Studio?

Ans: 
  1. In SAP HANA studio, choose Window –> Preferences –> SAP HANA Development –> Repository Access
  2. Choose Browse and enter the path to the SAP HANA client executable, regi.exe. For example, C:Program Filessaphdbclientregi.exe
  3. Choose Apply to enable the new setting.
  4. Choose OK to save the settings.

7. How to start HANA Studio in Linux?

Ans: To start the SAP HANA studio, perform the following steps:
  1. Open a shell and go to the installation directory, such as /usr/sap/hdbstudio
  2. Execute the following command “./hdbstudio”. The SAP HANA studio starts.
  3. To set the path to the repository client
    1. In SAP HANA studio, choose Window Preferences SAP HANA Development Repository Access
    2. Choose Browse… to enter the path to the SAP HANA client executable, regi. For example, /usr/sap/hdbclient
    3. Choose Apply to enable the new setting.
    4. Choose OK to save the settings.
8. What is SAP HANA XS Engine?

Ans: XS Engine is a JavaScript application server based on the Mozilla SpiderMonkey engine. The main idea of SAP HANA XS is to embed a full featured application server, web server, and development environment within the SAP HANA appliance itself.
Important points about SAP HANA XS:
  • XS is a Small footprint application server / web server.
  • It is the basis for an application development platform inside SAP HANA.
  • It simplifies architecture and lowers the TCO (total cost of operation).
  • It provides easy access to SAP HANA database via HTTP-based consumption
9. What is the purpose of xsaccess file in HANA XS project?

Ans: The application-access (.xsaccess) file enables you to specify who or what is authorized to access the content exposed by the application package and what content they are allowed to see.

The application-access file does not have a name before the dot (.); it only has the file extension .xsaccess. The contents of the .xsaccess file must be formatted according to JavaScript Object Notation (JSON) rules.
Example of .xsaccess file:

{
"exposed" : true,
"authentication" : { "method" : "Form"}
}

10. How can we create a job and schedule it in HANA?

Ans: With the help of XSJob file, we can run a service (for example, an XS JavaScript or a SQLScript) at a scheduled interval.
We first need to define the service either in XSJS or in SQLScript procedure. Then we can create XSJob file and mention the service details along with time interval. Finally from HANA Admin tool we can activate the job.

11. How can we create an XSODATA service which only allows to read data but prevents any INSERT/UPDATE/DELETE operation?

Ans: This can be done with the “forbidden” command. For example:

service {
"mySchema"."myTable" as "MyTable"
create forbidden
update forbidden
delete forbidden;
}

12. What is benefit of XOData compared to XSJS?

Ans: In HANA XSOData, there is a OData framework which provide many functionalities and we only need to provide details like data source, association etc. This is very helpful for developers as coding effort is almost zero. OData framework also takes care of security aspects like SQL injection, XSRF etc.
While in XSJS, we need to code everything our own. This results into more coding effort. We also need to take care of security aspects, performance etc.

13. Is it possible to call an external service from Internet in XS application? If yes, then how?

Ans: Yes, we can call an external service from Internet. This can be achieved with HTTP Destination (xshttpdest).
We first need to create an HTTP Destination file and provide the details of external service along with other security and proxy details. Then we can call this destination from XSJS using $.net.http.readDestination API.

14. What are the different Web-based tools available in HANA XS? How do we access them?

Ans: There are mainly 4 XS Web-based tools.
  • Editor: Inspect, create, change, delete and activate SAP HANA repository objects.
  • Catalog: Create, edit, execute and manage SQL catalog artifacts in the SAP HANA database.
  • Security: Manage users and roles.
  • Trace: View and download SAP HANA trace files and set trace levels (for example, info, error, debug).
The URL to access these tools is: http://<WebServerHost>:80<SAPHANAinstance>/sap/hana/xs/ide

15. What is HANA CDS? What are the artifacts we can create using CDS?

Ans: Core Data Services (CDS) artifacts are design-time definitions. When CDS file is activated, it generate runtime objects.
CDS can be used to create following database artifacts:
  • Create a table (entity)
  • Create an SQL views
  • Create an association between entities or views
  • Create a user-defined structured type
16. What is the file extension of XSJS library?

Ans: File extension of XSJS library is .xsjslib

17. Can we call an HTTP destination from an XSJS if HTTP destination is in a different package?

Ans: No.
We must keep the HTTP destination configuration in the same package as the application that uses it. An application cannot reference an HTTP destination configuration that is located in another application package.

18. Can we call an xsjslib from another XS project?

Ans: Yes. XSJS library (xsjslib) can be called from another XS project or another package.

19. Suppose we want to create an XS application and want to make it public. User should not need any HANA database user to access this application. Is it possible? If yes, how?

Ans: In .xsaccess file, we can set the authentication to null. After this anyone can open the application without user id and password.

20. How to perform backup and recovery operations?

Ans: During a regular operation, data is by default stored to the disk at savepoints in SAPHANA. As soon a there is any update and transaction, logs become active and get saved from the disk memory. In case of power failure, the database restarts like any other DB returning to the last savepoint log state. SAP HANA requires backup to protect against disk failure and reset DB to the previous state. The backups simultaneously as the users keep performing their tasks.

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