To achieve an active-passive failover model, where a process runs on a secondary AppNode only after the primary one fails, the process starter's activation must be set to Single AppNode. This setting ensures the process is active on only one AppNode within an AppSpace at any given time. The failover mechanism itself is managed by the underlying TIBCO BusinessWorks platform. When the AppSpace is configured for fault tolerance (with at least two AppNodes), the platform detects the failure of the active AppNode and automatically starts the process on a standby AppNode, thus achieving the desired failover behavior while respecting the single-instance constraint.

A. Multiple AppNodes: This setting activates the process starter on all AppNodes in the AppSpace simultaneously, which is used for load balancing or parallel processing, not active-passive failover.

C. Elastic AppNodes: This is not a standard activation setting within TIBCO BusinessWorks. It describes a general infrastructure capability rather than a specific process configuration option.

D. Failover AppNodes: This term describes the desired architectural outcome (high availability) but is not the name of the actual activation setting configured on the process starter in TIBCO BusinessWorks.

1. TIBCO BusinessWorks™ Application Development Guide (Version 6.8, March 2022):

Page 131, Chapter 10: Components, Section: "Component Process Starters": This section explicitly lists the available activation settings. It states, "The Activation check box in the Process Starters tab allows you to specify whether a process starter in a process is activated when it is deployed. You can select Single AppNode or Multiple AppNodes." It defines "Single AppNode" as: "The process starter is enabled on a single AppNode in an AppSpace." This confirms the name and function of the correct setting.

2. TIBCO BusinessWorks™ Administration Guide (Version 6.8, March 2022):

Page 71, Chapter 7: Fault Tolerance: This chapter explains the mechanism that enables the failover scenario. It states, "For fault tolerance, an AppSpace must have a minimum of two AppNodes... When an AppNode fails, the TIBCO Enterprise Administrator agent on the other machine detects the failure and starts the application on the available AppNode." This clarifies that the "Single AppNode" setting works in conjunction with a fault-tolerant AppSpace to achieve the goal.