Content Platform Engine updates usually ship with both server and client installation programs. You must run the client installation program for most components (including custom applications) that communicate directly with the Content Platform Engine server. Some components, such as IBM Content Navigator, have special tools to query the Content Platform Engine server and then to download and install the updated files as needed.
When you upgrade your FileNet® P8 system, you would upgrade these client files in the course of upgrading each respective component.