What happens when sub-processes are run as a "sub process" node?

When sub-processes are executed as a "sub-process" node within Appian, they consistently run in the same process execution engine as the parent process. This characteristic ensures that the sub-process can seamlessly share data with the parent process and maintain context throughout the execution. By running in the same engine, the parent and sub-process can communicate directly, which is essential for passing inputs and outputs, leveraging shared variables, and maintaining transaction integrity.

This approach allows for improved performance and stability, as context switching between different execution engines can introduce unnecessary overhead and complexity. In scenarios where a sub-process is integrated tightly with its parent, running within the same engine facilitates more efficient and reliable process management.