Why isn't setClientData() / putClientData() preferred over GlideAjax or getReference for server-to-c

[sndevastik]

Hi Community,

While exploring different ways to pass values from the server side to the client side in ServiceNow, I recently came across the use of putClientData() on the server side and getClientData() on the client side.

These methods seem to allow direct transfer of data between server and client without needing a separate GlideAjax call or getReference().

Given this capability, I'm curious — why are GlideAjax and getReference() still preferred or commonly used in practice over putClientData() / getClientData()?

Are there any limitations, best practice considerations, or disadvantages associated with the use of putClientData() that developers should be aware of?

Would love to hear your thoughts or real-world experiences.

Thanks!

[Ankur Bawiskar · Accepted solution]

@sndevastik 

data stored with putClientData() is stored in User' session and if we use it excessively it can lead to performance impact when more users are using that form.

Data stored in session might be risky.

If my response helped please mark it correct and close the thread so that it benefits future readers.