Best Practice for Defining Constants Used by a Catalog Item

[ShumaS]

Hello everyone,

I would like to ask about the best practice for defining and managing constants that are used by a specific Catalog Item.

Example

Let's assume we have a Catalog Item for requesting additional storage capacity.

• Maximum allowed capacity increase: 100 GB

This constant needs to be referenced in multiple places:

1. Catalog Client Scripts / UI Control

   • Display an error message when the requested value exceeds the limit.
   • Show additional input fields when the threshold is exceeded.

2. Process Automation / Flow Logic

   • Requests within the limit are processed automatically.
   • Requests exceeding the limit are routed to a responsible person for review and approval.

Options I Am Considering

1. System Property

My current thought is that this may be the closest approach to a best practice.

Pros

• Single source of truth.
• Easy to update without modifying multiple artifacts.

Concerns

• The value is only relevant to a specific Catalog Item, so I am not sure whether a system-wide configuration object is appropriate for such a localized setting.
• If many similar properties are added over time, could this have a negative impact on instance startup or performance?
• I assume properties are loaded only when referenced, but I would appreciate confirmation.

2. Decision Table

Pros

• Centralized management.
• Can potentially support future scenarios where thresholds vary by conditions.

Concerns

• It feels more like business-rule management than a simple constant definition.
• ServiceNow developers would understand it, but administrators or support personnel without platform knowledge may find it less intuitive.

3. Catalog Variable

Pros

• Easy to implement.
• Works well for UI Policies and Catalog Client Scripts.
• No additional server-side lookup is required, which minimizes latency.

Concerns

• Since the value exists on the client side, it could potentially be be manipulated.
• I am hesitant to use a client-side value as the basis for flow decisions or business logic.

4. Separate Catalog Variable and Flow Variable

Pros

• Easy to understand.
• Avoids relying on client-side values for automation decisions.

Concerns

• Creates duplicate configuration points.
• Lower maintainability due to double management of the same threshold.

Question

For a constant such as a maximum request size that must be referenced by both Catalog Client Scripts and Flow Designer logic, what would be considered the recommended or best-practice approach in ServiceNow?

If you have implemented similar requirements, I would be interested in learning:

• Which approach you selected.
• The reasoning behind the choice.
• Any performance, maintainability, or security considerations that influenced your decision.

My primary goal is to maintain a single source of truth while balancing maintainability, security, and performance. I would appreciate any guidance on how experienced ServiceNow architects and developers typically approach this type of requirement.

Thank you in advance for your advice.