Chunk-oriented log aggregation with Spring Batch

Concept

This migrated snapshot demonstrates a chunk-oriented Spring Batch job that reads CSV log records, enriches each message, and writes records to H2.

Hypothesis

Spring Batch can isolate file parsing, processing, persistence, and job launch concerns while supporting synchronous and asynchronous HTTP-triggered execution.

Architecture

JobLauncherController creates unique job parameters and selects a launcher. BatchConfig wires a classpath CSV reader, a processor that prefixes messages with [Processed], and a JDBC writer in chunks of ten. H2 stores both Spring Batch metadata and imported log_data rows.

Quick path

Prerequisites: Java 21 and Maven 3.6 or newer.

mvn spring-boot:run
curl -X POST 'http://localhost:8080/api/jobs/import-logs?filePath=input1.csv&sync=true'

A successful synchronous request should return job metadata with a completed status. The H2 console is available at http://localhost:8080/h2-console with JDBC URL jdbc:h2:mem:logdb, user sa, and an empty password.

Commands and verification

mvn test
mvn package

Results on 2026-07-18: mvn test completed with BUILD SUCCESS and reported no tests to run; mvn package -DskipTests completed with BUILD SUCCESS. The generated target/ directory was removed after verification. Runtime HTTP verification was skipped because it requires starting the local server; the build exercises application compilation without external services.

Configuration

src/main/resources/application.properties configures an in-memory H2 database and port 8080. It contains no production credentials. Input files must be classpath resources because the reader uses ClassPathResource.

Tradeoffs and status

Status: migrated snapshot. The processor deliberately sleeps for 100 ms per item to make execution differences visible. The endpoint exposes arbitrary classpath resource selection and the H2 console, which are learning conveniences rather than production security choices.

The source api.http was not migrated because it targeted an unrelated health endpoint on port 3000; the accurate curl request above replaces it. Application behavior was not changed.

Agent boundaries

Preserve the batch-learning scope and simulated processing delay unless an experiment explicitly studies performance. Do not commit H2 database files, Maven target/, IDE request history, or generated responses.