exclusive-join

Exclusive Join

Three vendor APIs (A, B, C) are queried in parallel for pricing. After all respond, a selection worker compares the results and picks the best offer. This demonstrates FORK_JOIN for parallel fan-out with a post-join aggregation step.

Workflow

FORK ──┬── ej_vendor_a ──┐
       ├── ej_vendor_b ──┤
       └── ej_vendor_c ──┤
                          JOIN
                           │
                    ej_select_best

Workflow exclusive_join_demo accepts query. Times out after 60 seconds.

Workers

VendorAWorker (ej_vendor_a) -- responds to the query with Vendor A's offer.

VendorBWorker (ej_vendor_b) -- responds to the query with Vendor B's offer.

VendorCWorker (ej_vendor_c) -- responds to the query with Vendor C's offer.

SelectBestWorker (ej_select_best) -- compares all three vendor responses and selects the best.

Workflow Output

The workflow produces winner, price as output parameters, capturing the result of each pipeline stage for downstream consumers and observability.

Task Configuration

• ej_vendor_a: retryCount=2, retryLogic=FIXED, retryDelaySeconds=?, timeoutSeconds=60, responseTimeoutSeconds=30
• ej_vendor_b: retryCount=2, retryLogic=FIXED, retryDelaySeconds=?, timeoutSeconds=60, responseTimeoutSeconds=30
• ej_vendor_c: retryCount=2, retryLogic=FIXED, retryDelaySeconds=?, timeoutSeconds=60, responseTimeoutSeconds=30
• ej_select_best: retryCount=2, retryLogic=FIXED, retryDelaySeconds=?, timeoutSeconds=60, responseTimeoutSeconds=30

These settings are declared in task-defs.json and apply independently to each task, controlling retry behavior, timeout detection, and backoff strategy without any changes to worker code.

Project Structure

This example contains 4 worker implementations in src/main/java/*/workers/, the workflow definition in src/main/resources/workflow.json, and integration tests in src/test/. The workflow exclusive_join_demo defines 3 tasks with input parameters query and a timeout of 60 seconds.

Tests

7 tests verify parallel vendor queries, response collection after join, and best-offer selection logic.

Running

See RUNNING.md for setup and execution instructions.