Building Microservices with Spring Boot and Apache Thrift. Part 2. Swifty services

时间：2021-12-11 15:37:38

http://bsideup.blogspot.com/2015/04/spring-boot-thrift-part2.html

In previous article I showed you how to use pure Apache Thrift to create protocols for your services. This time I will explain how to use Facebook Swift (not the best name for project BTW :)) to get rid of Thrift IDL files for server code.

Few words about Swift. Swift - Java annotation-based generator for Apache Thrift. It's priceless when you develop your APIs in Java and want to expose them to the other world using Apache Thrift.

Protocol

Lets recreate our previous example ( https://github.com/bsideup/spring-boot-thrift ) with it. Start with simple build.gradle file:

  apply plugin: 'java'
  apply plugin: 'spring-boot'
   
  buildscript {
  repositories {
  jcenter()
  }
   
  dependencies {
  classpath("org.springframework.boot:spring-boot-gradle-plugin:1.2.1.RELEASE")
  }
  }
   
  repositories {
  jcenter()
  }
   
  sourceCompatibility = 1.8
  targetCompatibility = 1.8
   
  dependencies {
   
  compile "org.projectlombok:lombok:1.16.2"
   
  compile("org.springframework.boot:spring-boot-starter-web")
   
  compile 'com.facebook.swift:swift-annotations:0.14.1'
  compile 'com.facebook.swift:swift-service:0.14.1'
  compile 'com.facebook.swift:swift-codec:0.14.1'
   
  compile 'com.facebook.nifty:nifty-core:0.14.1'
   
  compile 'org.apache.thrift:libthrift:0.9.1'
   
  testCompile "org.springframework.boot:spring-boot-starter-test"
  }
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Nothing special, Spring Boot with few Facebook Swift libraries.

Next we need to add Swift protocol classes:

  package com.example.calculator.protocol;
   
  import com.facebook.swift.service.ThriftMethod;
  import com.facebook.swift.service.ThriftService;
  import com.google.common.util.concurrent.ListenableFuture;
   
  @ThriftService
  public interface TCalculatorService {
   
  @ThriftMethod
  int calculate(int num1, int num2, TOperation op) throws TDivisionByZeroException;
  }

Exception is simple Swift struct which extend Exception (See Ma no TException)

  package com.example.calculator.protocol;
   
  import com.facebook.swift.codec.ThriftStruct;
   
  @ThriftStruct
  public final class TDivisionByZeroException extends Exception {
  }

Enums are handled with Swift, so we don't need to annotate them (but we can)

  package com.example.calculator.protocol;
   
  public enum TOperation {
  ADD,
  SUBTRACT,
  MULTIPLY,
  DIVIDE
  }
view rawTOperation.java hosted with ❤ by GitHub

Next - application main class for Spring Boot:

  package com.example.calculator;
   
  import com.example.calculator.protocol.TCalculatorService;
  import com.facebook.nifty.processor.NiftyProcessorAdapters;
  import com.facebook.swift.codec.ThriftCodecManager;
  import com.facebook.swift.service.ThriftEventHandler;
  import com.facebook.swift.service.ThriftServiceProcessor;
  import org.apache.thrift.protocol.*;
  import org.apache.thrift.server.TServlet;
  import org.springframework.boot.SpringApplication;
  import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
  import org.springframework.context.annotation.*;
   
  import javax.servlet.Servlet;
  import java.util.Arrays;
   
  @Configuration
  @EnableAutoConfiguration
  @ComponentScan
  public class CalculatorApplication {
  public static void main(String[] args) {
  SpringApplication.run(CalculatorApplication.class, args);
  }
   
  @Bean
  TProtocolFactory tProtocolFactory() {
  return new TBinaryProtocol.Factory();
  }
   
  @Bean
  ThriftCodecManager thriftCodecManager() {
  return new ThriftCodecManager();
  }
   
  @Bean
  Servlet thrift(ThriftCodecManager thriftCodecManager, TProtocolFactory protocolFactory, TCalculatorService exampleService) {
  ThriftServiceProcessor processor = new ThriftServiceProcessor(thriftCodecManager, Arrays.<ThriftEventHandler>asList(), exampleService);
   
  return new TServlet(
  NiftyProcessorAdapters.processorToTProcessor(processor),
  protocolFactory,
  protocolFactory
  );
  }
  }

Test

Now we're ready to write some tests:

  package com.example.calculator;
   
  import com.example.calculator.protocol.TCalculatorService;
  import com.example.calculator.protocol.TDivisionByZeroException;
  import com.example.calculator.protocol.TOperation;
  import com.facebook.nifty.client.HttpClientConnector;
  import com.facebook.swift.codec.ThriftCodecManager;
  import com.facebook.swift.service.ThriftClientManager;
  import org.apache.thrift.protocol.TProtocolFactory;
  import org.junit.Before;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.boot.test.IntegrationTest;
  import org.springframework.boot.test.SpringApplicationConfiguration;
  import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
  import org.springframework.test.context.web.WebAppConfiguration;
   
  import java.net.URI;
   
  import static org.junit.Assert.*;
   
  @RunWith(SpringJUnit4ClassRunner.class)
  @SpringApplicationConfiguration(classes = CalculatorApplication.class)
  @WebAppConfiguration
  @IntegrationTest("server.port:0")
  public class CalculatorApplicationTest {
   
  @Autowired
  TProtocolFactory protocolFactory;
   
  @Autowired
  ThriftCodecManager thriftCodecManager;
   
  @Value("${local.server.port}")
  protected int port;
   
  protected TCalculatorService client;
   
  @Before
  public void setUp() throws Exception {
  HttpClientConnector connector = new HttpClientConnector(URI.create("http://localhost:" + port + "/thrift/"));
   
  ThriftClientManager clientManager = new ThriftClientManager(thriftCodecManager);
  client = clientManager.createClient(connector, TCalculatorService.class).get();
  }
   
  @Test
  public void testAdd() throws Exception {
  assertEquals(5, client.calculate(2, 3, TOperation.ADD));
  }
   
  @Test
  public void testSubtract() throws Exception {
  assertEquals(3, client.calculate(5, 2, TOperation.SUBTRACT));
  }
   
  @Test
  public void testMultiply() throws Exception {
  assertEquals(10, client.calculate(5, 2, TOperation.MULTIPLY));
  }
   
  @Test
  public void testDivide() throws Exception {
  assertEquals(2, client.calculate(10, 5, TOperation.DIVIDE));
  }
   
  @Test(expected = TDivisionByZeroException.class)
  public void testDivisionByZero() throws Exception {
  client.calculate(10, 0, TOperation.DIVIDE);
  }
  }

As you can see, only difference here (compared to Thrift version) is setUp method.
Diff with Thrift version

Implementation

We still have no Swift service implementation. Implementation of handler looks almost the same asprevious:

  package com.example.calculator.handler;
   
  import com.example.calculator.protocol.TCalculatorService;
  import com.example.calculator.protocol.TDivisionByZeroException;
  import com.example.calculator.protocol.TOperation;
  import org.springframework.stereotype.Component;
   
  import com.example.calculator.service.CalculatorService;
  import org.springframework.beans.factory.annotation.Autowired;
   
  @Component
  public class CalculatorServiceHandler implements TCalculatorService {
   
  @Autowired
  CalculatorService calculatorService;
   
  @Override
  public int calculate(int num1, int num2, TOperation op) throws TDivisionByZeroException {
  switch(op) {
  case ADD:
  return calculatorService.add(num1, num2);
  case SUBTRACT:
  return calculatorService.subtract(num1, num2);
  case MULTIPLY:
  return calculatorService.multiply(num1, num2);
  case DIVIDE:
  try {
  return calculatorService.divide(num1, num2);
  } catch(IllegalArgumentException e) {
  throw new TDivisionByZeroException();
  }
  default:
  throw new IllegalArgumentException("Unknown operation " + op);
  }
  }
  }

Diff with Thrift version

Now if you will run tests you should see all tests green.

Building Microservices with Spring Boot and Apache Thrift. Part 2. Swifty services

Thrift integration

But hey, how about other non-Java consumers of service? Don't worry, Swift comes with a tool for generating *.thrift files from annotated Java classes:https://github.com/facebook/swift/tree/master/swift2thrift-generator-cli

Example output for our service will be:

  namespace java.swift com.example.calculator.protocol
  namespace java com.example.calculator.protocol
  namespace py com.example.calculator.protocol
  namespace as3 com.example.calculator.protocol
   
   
  enum TOperation {
  ADD, SUBTRACT, MULTIPLY, DIVIDE
  }
   
  exception TDivisionByZeroException {
  }
   
  service TCalculatorService {
  i32 calculate(1: i32 arg0, 2: i32 arg1, 3: TOperation arg2) throws (1: TDivisionByZeroException ex1);
  }
view rawcalculator.thrift hosted with ❤ by GitHub

Conclusion

Full source files for this example can be found at GitHub: https://github.com/bsideup/spring-boot-swift

Next time I will show you how to write Async Thrift services using Swift with minimal changes. Stay tuned!

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