Extensibility
What to know
Extensibility covers how Appian connects to external systems and extends behavior: integrations (connected systems, REST/SOAP), web APIs exposed by Appian, plugins, and expression/scripting used inside process and interface logic. A candidate should understand connected systems as reusable configuration for calling external services, and integration objects that use them. Know that Appian can expose its own web APIs so external systems start processes or read data. Understand plugins as packaged extensions installed into an environment, and that expressions (functions, rules, constants) drive dynamic behavior without custom code.
Traps
A common trap is confusing a connected system (the configured endpoint/auth) with an integration (the specific call built on it). Another is assuming an integration runs synchronously everywhere - some calls are asynchronous and return later. Questions may conflate plugins (installed, environment-level) with integrations (configured per object). Also watch for authentication confusion: the connected system holds credentials/authentication, not each integration.
Rule of thumb
Ask direction: is Appian calling out (integration) or being called (web API)? Then ask where config lives: shared endpoint/auth (connected system) vs the specific operation (integration).
Worked example
An external billing system must notify Appian when an invoice is paid. Appian exposes a web API that starts a process; the billing system calls it. Appian then calls a tax service via an integration built on a connected system that stores the service URL and credentials.