Question on Parent/Child App services -platform host/module context

[Tom Sienkiewicz]

Hi All,

I'd like to better understand the implications of parent/child app services in the following scenario:

- We have a platform host Business App (e.g. ServiceNow)

- We have a child platform app Business App (e.g. Project Management)

- I want to represent both entire platform as well as the module as App services for operations.

- If the host App service is impacted, I'd like for any app/module App Service running on that host to be automatically impacted too (if that makes sense?).

When using the App Service wizard, we can define a "parent App Service" and this creates a depends on::used by relationship. Which should be the parent App in that context - the host or the module? This article states the child impacts the parent, is the child typically the downstream node causing the impact upwards?   View impact of child service on parent service

Would the above setup automatically propagate the impact upstream e.g. in dependency views? Will it allow to automatically populate the "impacted services" and "impacted business applications" related lists on Incident?

What is best practice here - if the incident impacts the host App Service / Business App, should it also be impacting any app/module app service/business app? Am I overcomplicating this?

Can you provide some other examples in which you have set up such a parent/child relationship between App Services?

Many thanks,

Tom

[debendudas · Accepted solution]

Hi @Tom Sienkiewicz , 

Thanks for asking these wonderful questions related to CSDM. They will also help others understand CSDM in depth.

To answer your question,

1) Which should be the Parent Application Service - the host or the module?

When the wizard asks for a Parent App Service, it creates a Depends on :: Used by relationship.

Parent ➡️ Depends on :: Used by ⬅️ Child

That is, the parent CI is depends on the child CI. 

So, if your Project Management module depends on the ServiceNow Platform host:

Parent (module) = Project Management – PROD
Child (host) = ServiceNow Platform – PROD

This orientation ensures that an issue on the host (child) properly impacts the module (parent) in upstream impact calculations and views because the impact flows from the supporting CI (child) to the consumer (parent) in a depends‑on relation.

This matches the behavior you’re looking for:

"If the host App service is impacted, I'd like for any app/module App Service running on that host to be automatically impacted too"

2) Would the above setup automatically propagate the impact upstream e.g. in dependency views? Will it allow to automatically populate the "impacted services" and "impacted business applications" related lists on Incident?

Yes, but only if the correct configurations are in place.

ServiceNow can automatically populate the Impacted Services and Impacted Business Applications lists on an Incident when:

• The Incident properties for impact refresh are enabled ( com.snc.incident.refresh_impacted.include_affected_cis).
• The Application Services (Service Instances) have proper CI associations in the svc_ci_assoc table.

If these conditions are met, running Refresh Impacted Services will update those related lists automatically.

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