In TIBCO ActiveMatrix BusinessWorks, error handling at the activity level is primarily implemented using two mechanisms. The first is an Error Transition, which is a specific type of transition link originating from an activity that is executed only when that activity throws a fault. The second method is using a Fault Handler, which is attached to a Scope. By placing one or more activities inside a Scope, the Fault Handler acts as a structured try-catch block, catching any unhandled exceptions from the enclosed activities and executing a defined error-handling process.

B. onError Activity: There is no standard, built-in activity named "onError" in the TIBCO ActiveMatrix BusinessWorks palettes for general error handling.

C. Conditional Transitions: These transitions execute based on the evaluation of a data-based XPath expression (e.g., statuscode=200), not on the occurrence of a fault state.

E. Event Handlers: Event Handlers are designed to process asynchronous events (like timers or incoming messages) that can occur at any point, not to handle synchronous faults from activities.

1. TIBCO ActiveMatrix BusinessWorks™ Concepts, Release 6.8.1, March 2022:

For Error Transitions (A): Chapter 6: Process Definition, Section: "Transitions". The documentation states, "There are three types of transitions: Success, Success with conditions, and Error... An error transition is created to handle an error that occurs when the activity is running."

For Fault Handlers (D): Chapter 6: Process Definition, Section: "Scopes". The documentation explains, "A scope is a container for a collection of activities... A scope can have one or more fault handlers to catch and handle faults that may be thrown by the activities inside the scope."

For Conditional Transitions (C): Chapter 6: Process Definition, Section: "Transitions". This section distinguishes "Success with conditions" transitions, which are based on XPath, from Error transitions.

For Event Handlers (E): Chapter 6: Process Definition, Section: "Event Handlers". This section describes how event handlers are used for asynchronous events, separate from the main process flow.