How to Set Principal Classes for ITSM

SNFan
Tera Expert
‎03-21-2025 02:15 PM
The 'Configuration Item' (CI) field on a form may appear simple, but it offers numerous options that can significantly impact your workflows in Incident, Problem, and Change management. Selecting a relevant CI can automate your workflows such as setting the Assignment group or indicating dependencies.

 

Through this 'window,' you access your Configuration Management Database (CMDB), which can contain millions of records. In ServiceNow, a single server can translate into hundreds of records, especially if you're using a tool like ServiceNow Discovery. To facilitate easier CI selection for users, ServiceNow provides an out-of-the-box reference qualifier for this field based on 'Principal Classes.'

 

Which Principal Classes to Select?

Principal Classes indicate the classes most valuable to your workflows. By default, no classes are designated as 'Principal,' so you will need to define these yourself. But which ones should you choose?

 

Typically, a good starting point for selecting Principal Classes includes:

  • Application Services (excluding Business Applications, according to CSDM guidance)

    • Also include App Service child classes.

  • Most Hardware Classes

    • Exceptions might exist if you have IoT (Internet-of-Things) devices in your CMDB.

  • Other Technology with Dedicated Support Teams

    • This could include databases, database catalogs, or other classes under Application (cmdb_ci_appl).

Setting Principal Classes

To designate which classes are 'Principal,' you use the CI Class Manager. This involves checking a box on the form for the specific class, and it only applies to that exact class. You'll need to individually check the box for any subclasses that you also want to include.

SNFan_0-1742591526693.png

 

If you wish to review the script that determines this logic, you can find it in the function getConfigurationItemFilter in the following script include: TaskUtilsSNC Script Include 

https://<instance name>.service-now.com/nav_to.do?uri=sys_script_include.do?sys_id=1cf5818a878010100e3dd61e36cb0b4a

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3 Comments
Mannapuram
Tera Guru
‎07-01-2025 09:35 AM
‎07-01-2025 09:35 AM

Adding to above info, the list of Prinicpal classes can be found in "cmdb_class_info" with 'Prinicpal Calss' field set to true. Along with this, there is a system property (com.snc.task.principal_class_filter) to control list tables who can use it. 

DonnaOlsen
Tera Expert
‎07-25-2025 07:54 AM
‎07-25-2025 07:54 AM

If I want to use Business Service and Technical Service records selectable from the Service field, do these need to be marked as Principal CIs? Because if so, I would imagine they are also available for selection in the configuration item field, which I would not want it to be.

0 Helpfuls
Mannapuram
Tera Guru
‎07-28-2025 08:29 AM
‎07-28-2025 08:29 AM

@DonnaOlsen  Business Service and Technical Service are child classes of Service class (cmdb_ci_service.LIST). If you want to use these under Service on Incident, then don't enable their Principal class tag, as that will enable them on Configuration tab as well. 

OOB, Service field on Task table is reference to Service table, thus, only child classes of Services will be shown. You can just use the OOB way. 

Once you enable the principal class tag, then only those classes are shown in Service and Configuration item fields. 

If you still have questions, please post them.