spring-projects#361 - Add example for MongoDB 4.0 transactions.

README.md

@@ -31,6 +31,7 @@ We have separate folders for the samples of individual modules:
 * `reactive` - Example project to show reactive template and repository support.
 * `security` - Example project showing usage of Spring Security with MongoDB.
 * `text-search` - Example project showing usage of MongoDB text search feature.
+* `transactions` - Example project for synchronous and reactive MongoDB 4.0 transaction support.
 
 ## Spring Data REST
 

mongodb/pom.xml

@@ -27,6 +27,7 @@
 		<module>reactive</module>
 		<module>security</module>
 		<module>text-search</module>
+		<module>transactions</module>
 	</modules>
 
 	<dependencies>

mongodb/transactions/README.md

@@ -0,0 +1,79 @@
+# Spring Data MongoDB - Transaction Sample
+
+This project contains samples for upcoming MongoDB 4.0 transactions.
+
+## Running the Sample
+
+The sample uses multiple embedded MongoDB processes in a [MongoDB replica set](https://docs.mongodb.com/manual/replication/).
+It contains test for both the synchronous and the reactive transaction support in the `sync` / `reactive` packages.   
+
+You may run the examples directly from your IDE or use maven on the command line.
+
+**INFO:** The operations to download the required MongoDB binaries and spin up the cluster can take some time. Please 
+be patient. 
+
+## Sync Transactions
+
+`MongoTransactionManager` is the gateway to the well known Spring transaction support. It lets applications use 
+[the managed transaction features of Spring](http://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference/html/transaction.html).
+The `MongoTransactionManager` binds a `ClientSession` to the thread. `MongoTemplate` detects the session and operates
+on these resources which are associated with the transaction accordingly. `MongoTemplate` can also participate in 
+other, ongoing transactions.
+
+```java
+@Configuration
+static class Config extends AbstractMongoConfiguration {
+
+	@Bean
+	MongoTransactionManager transactionManager(MongoDbFactory dbFactory) {
+		return new MongoTransactionManager(dbFactory);
+	}
+
+	// ...
+}
+
+@Component
+public class TransitionService {
+
+    @Transactional
+    public void run(Integer id) {
+
+    	Process process = lookup(id);
+
+    	if (!State.CREATED.equals(process.getState())) {
+    		return;
+    	}
+
+    	start(process);
+    	verify(process);
+    	finish(process);
+    }
+}
+```
+
+## Reactive transactions
+
+`ReactiveMongoTemplate` offers dedicated methods for operating within a transaction without having to worry about the
+commit/abort actions depending on the operations outcome. There's currently no session or transaction integration 
+with reactive repositories - we apologize for that!
+
+**NOTE:** Please note that you cannot preform meta operations, like collection creation within a transaction.
+
+```java
+@Component
+public class RactiveTransitionService {
+
+    public Mono<Integer> run(Integer id) {
+
+		return template.inTransaction().execute(action -> {
+
+			return lookup(id) //
+			        .filter(State.CREATED::equals)
+			        .flatMap(process -> start(action, process))
+			        .flatMap(this::verify)
+			        .flatMap(process -> finish(action, process));
+
+		}).next().map(Process::getId);
+	}
+}
+```

mongodb/transactions/pom.xml

@@ -0,0 +1,72 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.springframework.data.examples</groupId>
+        <artifactId>spring-data-mongodb-examples</artifactId>
+        <version>2.0.0.BUILD-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>spring-data-mongodb-transactions</artifactId>
+    <name>Spring Data MongoDB - Transactions</name>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.mongodb</groupId>
+                    <artifactId>mongodb-driver</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.data</groupId>
+            <artifactId>spring-data-mongodb</artifactId>
+            <version>2.1.0.BUILD-SNAPSHOT</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.data</groupId>
+            <artifactId>spring-data-commons</artifactId>
+            <version>2.1.0.BUILD-SNAPSHOT</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mongodb</groupId>
+            <artifactId>mongo-java-driver</artifactId>
+            <version>3.8.0-beta2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mongodb</groupId>
+            <artifactId>mongodb-driver-async</artifactId>
+            <version>3.8.0-beta2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mongodb</groupId>
+            <artifactId>mongodb-driver-reactivestreams</artifactId>
+            <version>1.9.0-beta1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>io.projectreactor</groupId>
+            <artifactId>reactor-core</artifactId>
+            <version>3.1.7.RELEASE</version>
+        </dependency>
+
+        <dependency>
+            <groupId>io.projectreactor</groupId>
+            <artifactId>reactor-test</artifactId>
+            <version>3.1.7.RELEASE</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+</project>

mongodb/transactions/src/main/java/example/springdata/mongodb/Process.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.springdata.mongodb;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+@Data
+@AllArgsConstructor
+@Document("processes")
+public class Process {
+
+	@Id Integer id;
+	State state;
+	int transitionCount;
+
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/State.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.springdata.mongodb;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+public enum State {
+
+	CREATED, ACTIVE, DONE
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/reactive/ReactiveProcessRepository.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.springdata.mongodb.reactive;
+
+import example.springdata.mongodb.Process;
+
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+public interface ReactiveProcessRepository extends ReactiveCrudRepository<Process, Integer> {
+
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/reactive/ReactiveTransitionService.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.springdata.mongodb.reactive;
+
+import example.springdata.mongodb.Process;
+import example.springdata.mongodb.State;
+import lombok.RequiredArgsConstructor;
+import reactor.core.publisher.Mono;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.springframework.data.mongodb.core.ReactiveMongoOperations;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.Update;
+import org.springframework.stereotype.Service;
+import org.springframework.util.Assert;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+@Service
+@RequiredArgsConstructor
+public class ReactiveTransitionService {
+
+	final ReactiveProcessRepository repository;
+	final ReactiveMongoTemplate template;
+
+	final AtomicInteger counter = new AtomicInteger(0);
+
+	public Mono<Process> newProcess() {
+		return repository.save(new Process(counter.incrementAndGet(), State.CREATED, 0));
+	}
+
+	public Mono<Integer> run(Integer id) {
+
+		return template.inTransaction().execute(action -> {
+
+			return lookup(id) //
+					.flatMap(process -> start(action, process)) //
+					.flatMap(this::verify) //
+					.flatMap(process -> finish(action, process));
+
+		}).next().map(Process::getId);
+	}
+
+	private Mono<Process> finish(ReactiveMongoOperations operations, Process process) {
+
+		return operations.update(Process.class).matching(Query.query(Criteria.where("id").is(process.getId())))
+				.apply(Update.update("state", State.DONE).inc("transitionCount", 1)).first() //
+				.then(Mono.just(process));
+	}
+
+	Mono<Process> start(ReactiveMongoOperations operations, Process process) {
+
+		return operations.update(Process.class).matching(Query.query(Criteria.where("id").is(process.getId())))
+				.apply(Update.update("state", State.ACTIVE).inc("transitionCount", 1)).first() //
+				.then(Mono.just(process));
+	}
+
+	Mono<Process> lookup(Integer id) {
+		return repository.findById(id);
+	}
+
+	Mono<Process> verify(Process process) {
+
+		Assert.state(process.getId() % 3 != 0, "We're sorry but we needed to drop that one");
+		return Mono.just(process);
+	}
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/sync/ProcessRepository.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.springdata.mongodb.sync;
+
+import example.springdata.mongodb.Process;
+
+import org.springframework.data.repository.CrudRepository;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+interface ProcessRepository extends CrudRepository<Process, Integer> {
+
+}