Implementing CREATE operation

In the previous step, we defined service methods. In this step, we'll implement one of the service methods to create a blog post and again, try making a call to a service method. Also, we'll use Armeria's ServerExtension for testing.

What you need

You need to have the following files obtained from previous steps. You can always download the full version, instead of creating one yourself.

• Generated Java code
• BlogService.java
• Main.java
• BlogServiceTest.java

1. Implement server-side

Let's implement a service method createBlogPost() in the BlogService class.

1. Create an ID generator to issue temporary blog post IDs and a map to contain blogs posts.

BlogService.java

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

public final class BlogService extends BlogServiceGrpc.BlogServiceImplBase {
  private final AtomicInteger idGenerator = new AtomicInteger();
  private final Map<Integer, BlogPost> blogPosts = new ConcurrentHashMap<>();
}

2. Add a service method, createBlogPost():
   1. Create a BlogPost object with request parameters.
   2. Save the post information in the map.
   3. Return the information of the blog post created.

BlogService.java

import java.time.Instant;
import io.grpc.stub.StreamObserver;

final class BlogService extends BlogServiceGrpc.BlogServiceImplBase {
  @Override
  public void createBlogPost(CreateBlogPostRequest request, StreamObserver<BlogPost> responseObserver) {
    final int id = idGenerator.getAndIncrement(); // Generate post ID
    final Instant now = Instant.now();            // Get current time
    final BlogPost updated = BlogPost.newBuilder()
                     .setId(id)
                     .setTitle(request.getTitle())
                     .setContent(request.getContent())
                     .setModifiedAt(now.toEpochMilli())
                     .setCreatedAt(now.toEpochMilli())
                     .build();
    blogPosts.put(id, updated);
    responseObserver.onNext(updated);
    responseObserver.onCompleted();
  }
}

2. Register a ServerExtension

In the previous test code, we've connected directly to the server. This time, let's use Armeria's ServerExtension instead. This approach automatically handles set-up and tear-down of a server for testing. Now we don't have to invoke the main method to set up a server before running our tests.

1. In the BlogServiceTest class, remove the connect() method to eliminate dependency on the main method.

BlogServiceTest.java

public class BlogServiceTest {
  ...
  @Test
  void connect() {...} // Remove this method
}

2. Register a ServerExtension as follows. Note that the service instance is added to the configuration.

BlogServiceTest.java

import org.junit.jupiter.api.extension.RegisterExtension;
import com.linecorp.armeria.server.ServerBuilder;
import com.linecorp.armeria.server.grpc.GrpcService;
import com.linecorp.armeria.testing.junit5.server.ServerExtension;

public class BlogServiceTest {
  ...
  @RegisterExtension
  static final ServerExtension server = new ServerExtension() {
    @Override
    protected void configure(ServerBuilder sb) throws Exception {
      sb.service(GrpcService.builder()
                    // Add the service to the configuration
                    .addService(new BlogService())
                    .build());
    }
  };
}

3. Set up a client for testing

In the BlogServiceTest class, add a method as follows. This will set up a client before executing each test cases.

BlogServiceTest.java

import org.junit.jupiter.api.BeforeAll;

@BeforeAll
static void beforeAll() {
  client = GrpcClients.newClient(server.httpUri(),
                 BlogServiceBlockingStub.class);
}

4. Test creating a blog post

Let's test if we can create a blog post.

1. In the BlogServiceTest class, add a test method as follows.

BlogServiceTest.java

import static org.assertj.core.api.Assertions.assertThat;
import com.fasterxml.jackson.core.JsonProcessingException;

@Test
void createBlogPost() throws JsonProcessingException {
  final CreateBlogPostRequest request = CreateBlogPostRequest.newBuilder()
                   .setTitle("My first blog")
                   .setContent("Hello Armeria!")
                   .build();
  final BlogPost response = client.createBlogPost(request);
  assertThat(response.getTitle()).isEqualTo(request.getTitle());
  assertThat(response.getContent()).isEqualTo(request.getContent());
}

2. Run the test case on your IDE or using Gradle.

./gradlew test

The service worked as expected if you see the test case passed.

What's next

In this step, we've implemented a method for creating a blog post. We've also registered ServerExtension to our test.

Next, at Step 4. Implement READ, we'll implement a READ operation to read a single post and also multiple posts.