Read the result of any output port of an operator, not only the first #9053

Feature Summary

An operator with more than one output, such as Split or If, has every output stored when it is at the end of a workflow or its result is kept. Only the first output can be read, though: result pages are always read from port 0. So a Split's second output, or an If's True branch, cannot be shown anywhere in the UI.

This is a step toward the result windows discussed in #8842, where each output of an operator gets its own tab. Part of #9052.

Proposed Solution or Design

Let a result page request name the output port to read, with the first port as the default so current requests are unchanged. The reply says which port it read and how many rows that port has, so a client can page through a port the running execution does not report on. The live result updates keep following the first port.

Affected Area

Workflow Engine (Amber)