asmhatre
b4a623b889
Separate write/read DataSources, a JPA command side, and two interchangeable projection listeners (sync and @Async) demonstrating the real latency-versus- freshness trade-off CQRS forces. Includes a reflection-based proof that the query side has no dependency on the write side, and a real failure/fix transcript for the -parameters compiler flag this standalone reactor doesn't inherit from spring-boot-starter-parent.
52 lines
2.6 KiB
Java
52 lines
2.6 KiB
Java
package com.ankurm.cqrsdemo;
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import com.ankurm.cqrsdemo.command.OrderCommandController.LineRequest;
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import com.ankurm.cqrsdemo.command.OrderCommandController.PlaceOrderRequest;
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import com.ankurm.cqrsdemo.command.OrderCommandController.PlaceOrderResponse;
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import com.ankurm.cqrsdemo.query.OrderSummary;
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import org.junit.jupiter.api.Test;
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import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate;
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import org.springframework.boot.resttestclient.TestRestTemplate;
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import org.springframework.boot.test.context.SpringBootTest;
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import org.springframework.http.ResponseEntity;
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import java.util.List;
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import static org.assertj.core.api.Assertions.assertThat;
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/**
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* Default profile: no {@code async-projection}, so {@link com.ankurm.cqrsdemo.read.SyncOrderSummaryProjection}
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* is active. The projection's simulated write delay (300ms, see {@code application.properties})
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* runs on the same thread that is about to answer the command's HTTP request, so it shows up
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* directly in how long {@code POST /orders} takes -- and because of that, the read model is
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* already correct the instant the command returns, with no waiting required.
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*/
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@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
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@AutoConfigureTestRestTemplate
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class SyncProfileLatencyTest {
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@org.springframework.beans.factory.annotation.Autowired
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private TestRestTemplate rest;
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@Test
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void placingAnOrderTakesAtLeastTheSimulatedProjectionDelayAndTheReadModelIsImmediatelyConsistent() {
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PlaceOrderRequest request = new PlaceOrderRequest("Priya",
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List.of(new LineRequest("USB-C-CABLE", 2, 1299), new LineRequest("USB-C-HUB", 1, 4999)));
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long start = System.currentTimeMillis();
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ResponseEntity<PlaceOrderResponse> placed = rest.postForEntity("/orders", request, PlaceOrderResponse.class);
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long elapsedMs = System.currentTimeMillis() - start;
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String orderId = placed.getBody().orderId();
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System.out.println("POST /orders (sync profile) took " + elapsedMs + " ms, orderId=" + orderId);
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assertThat(elapsedMs).isGreaterThanOrEqualTo(300L);
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ResponseEntity<OrderSummary> summary = rest.getForEntity("/order-summaries/" + orderId, OrderSummary.class);
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System.out.println("Immediately after POST returned, GET /order-summaries/" + orderId
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+ " -> status=" + summary.getStatusCode() + ", body=" + summary.getBody());
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assertThat(summary.getBody()).isNotNull();
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assertThat(summary.getBody().totalCents()).isEqualTo(2 * 1299 + 4999);
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assertThat(summary.getBody().status()).isEqualTo("PLACED");
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}
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}
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