When to Use Client-Callable Flows/Subflows/Actions: Let's understand with an Example!

Hemanth M1 · a month ago

Hello Community,

Have you used Client callable Flows, Subflows, or Actions and do you know how to set them up and when to use them? Can we replace GlideAjax with a client-callable Subflow or Action?

Let's try to understand all of these with a setup 😁

1)What are client callable Flows/Subflows/Actions?

These are traditional Flows, Subflows, or Actions; however, you can call them from client-side configurations (e.g., Client Scripts, UI Action scripts, UI Policies) to perform server-side operations or transactions like Script Includes.

2)When you use them?

These are typically used when you need to fetch data on the fly on the client side from external sources, Can also used internally when you need to track server side transactions from the client (although this can introduce some performance overhead). In these cases, you can replace a GlideAjax setup.

Examples:

Get requestor details from an external database, OR from Active Directory OR fetching information from a website.
Get requestor email, manager information and populate them on the catalog item form (Only if required and crucial to track the transactions)

3)How to set a Client callable Flow/Subflow/Action?

Let's do it on the action, its the same for Flow and Subflow

A)Go to Flow Designers > Actions> Create a new action or Open a New Action

B)Create a Action and go to the "Manage Security"

C)Check "Callable by Client API" and you have to select appropriate ACLs to execute this action

D)What if no ACLs found?? Create one

ex: Type is "client_callable_flow_objec"t, Give it a Name and select appropriate role

E)Come back to the action, Manage Security>ACLS>elect that one created, Update

Now the setup is ready. Here, I am using an external API to get the currency exchange value.
For example: What’s the INR value for 1 US dollar. Let’s set this up in the Action.

4)Set up the integration using Rest Step

A)Go to the action use REST step, update API details

B)This action takes the currency type (INR, EUR, CAD) as input and gives the current rate in USD.
For example: 1 USD = 87.3 INR.

5) I have a catalog item set up to provide logged in user information and options to select the currency.

Output:

6)Let's use the actions we created in this catalog item during onLoad and onChange (current value) Client scripts😍

A)Go to the Action> Click on "Create Code Snippet"

Go to client block and copy the code. This runs Async

B)Now go the catalog item, create a onLoad or OnChange client script as below.

You can also do it Onload if required

Lets look at the Output 😎:

Navigate to the Catalog Item:

Select any Currency:

Here we go😍

Now we are getting this value on the fly during form submission. This is just an example, but if we need to get information from an external database to validate before users submit forms, client callable flows, Subflows, and actions come in very handy.

Flow execution logs: Here you can easily track the transactions!

More info on this website here : https://app.currencyapi.com

Same way, you can use the lookup step to get the requestor's details and set them on the client side! - Consider the implications before implementing.

Thank you,
Hemanth
Certified Technical Architect (CTA), ServiceNow MVP 2024, 2025

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