Migrating from 0.8 to 0.9

0.9 turns the sequential runtime into a parallel one. Most graphs need no change; the three points below are the exceptions.

A second direct edge is now a branch

Behaviour: in 0.8, only the first direct edge out of a node was taken and the others were ignored. In 0.9 every direct edge is taken, and the branches run in parallel.

.addEdge("plan", "research")
.addEdge("plan", "draft")     // 0.8: ignored. 0.9: runs in parallel with "research"

If you relied on the old behaviour, delete the extra edges, or make the routing explicit with Edge.conditional, whose first match still wins alone.

Branches must not write the same state key

Behaviour: two branches writing different values to the same StateKey now fail the run with a StateConflictException. Give each branch its own key and let the join read them. Writing the same value from both branches is not a conflict.

Checkpoint carries a frontier and a memo

Checkpoint gains nextNodes() and completedNodes(). The single-node constructor still exists, so new Checkpoint(runId, "node", context, iterations, interrupt) keeps compiling; nextNode() returns the first node of the frontier.

A custom CheckpointStore needs no change. A custom CheckpointCodec must persist both new fields, or a paused fan-out will resume on one branch and replay completed nodes. The bundled Jackson codec writes format v3 and still reads v1 and v2.

New in 0.9

Nothing to migrate.

• Builder.maxConcurrency(int), default 4.
• Builder.onRejection(gatedNode, target) and ResumeOptions.ofRejection(node, reason).
• ResumeOptions.withInvalidated(node) to force a memoized node to run again.
• RunEventType.NODE_SKIPPED in the run log.
• See Parallel branches.