Debugging My n8n-Like Workflow Engine | Jackson JSON Parsing & Node Execution | Part 14

Part 14 of building an n8n-inspired workflow automation engine using Java, Spring Boot, PostgreSQL, and Jackson. Today's work focused on debugging the TRANSFORM node and improving execution reliability in my custom workflow engine. TRANSFORM NODE DEBUGGING My workflow was failing with the error "TRANSFORM node requires an operation array", even though the database contained the expected configuration. After investigating the runtime logs, I identified the root cause: the node configuration was being returned as a textual JsonNode containing serialized JSON instead of a JSON object node. Because of this, accessing the operations property returned null. I explored how to detect textual JSON using isTextual() and parse it with Jackson's readTree() before accessing the configured operations. I also identified a spelling mismatch between SET_FILED in the executor and SET_FIELD in the configuration. This would cause another failure even after fixing the JSON parsing issue. EXECUTION ENGINE AND WORKER RECOVERY I continued reviewing the execution lifecycle and repository operations responsible for claiming executions, renewing worker leases, completing executions conditionally, and recovering executions with expired leases. These mechanisms help ensure that a worker cannot complete an execution after losing ownership or allowing its lease to expire. HTTP REQUEST NODE I reviewed configuration handling in the HTTP Request executor and investigated earlier errors involving missing HTTP methods and invalid JSON configuration. Later execution records showed successful HTTP requests to JSONPlaceholder, demonstrating progress in the HTTP execution path. JACKSON AND JAVA CONCEPTS I also worked through the difference between JSON strings and JSON objects, converting JsonNode values into Java objects, validating webhook payloads with instanceof pattern matching, and handling maps and lists in Java. WHAT'S NEXT Fix and retest the TRANSFORM node, verify that the configured operations produce the expected output, and confirm that the complete Manual Trigger → Transform → HTTP Request → Delay workflow executes successfully. I'll also investigate why node configurations become textual JSON and determine whether configuration normalization should happen centrally rather than separately in each executor. Tech stack: Java, Spring Boot, PostgreSQL, Jackson, Spring RestClient, and a custom workflow execution engine. #Java #SpringBoot #WorkflowAutomation #N8nClone #WorkflowEngine #ExecutionEngine #NodeExecutor #TransformNode #HttpRequestNode #DelayNode #IfNode #Jackson #JsonNode #JSONParsing #PostgreSQL #WorkerRecovery #ExecutionLifecycle #RetryMechanism #DataTransformation #ConditionalBranching #RestClient #BackendDevelopment #JavaBackend #SpringBootProject #WorkflowExecution