Flow is a collection of steps, which can be reusable. For example, we can create a flow that contain some common steps across the jobs.
For example, you can create a flow that read all the subscribers of a job and send an email that some Job X is started to all the subscribers. Since this is a common step, we can create a flow and reuse it in multiple jobs.
How to create a flow?
Using FlowBuilder, you can create a flow.
@Bean
public Flow sendNotification() {
FlowBuilder<Flow> flowBuilder = new FlowBuilder<Flow>("notification");
flowBuilder.start(readSubscribers()).next(sendEmail()).end();
return flowBuilder.build();
}
Once you define a flow, you can use it anywhere in the job steps. For example, I used this flow as starting step.
@Bean
public Job job(Flow sendNotification) {
return jobBuilderFactory.get("My-Job").start(sendNotification).next(step1()).next(step2()).next(step3()).end().build();
}
Find the below working application.
Step 1: Create new maven project ‘flow-demo’.
Step 2: Update pom.xml with maven dependencies.
pom.xml
<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>
<groupId>com.sample.app</groupId>
<artifactId>flow-demo</artifactId>
<version>1</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.springframework.batch/spring-batch-core -->
<dependency>
<groupId>org.springframework.batch</groupId>
<artifactId>spring-batch-core</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
</dependencies>
</project>
Step 3: Create new package ‘com.sample.app.configuration’ and define EmailFlowConfiguration.
EmailFlowConfiguration.java
package com.sample.app.configuration;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.StepContribution;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.job.builder.FlowBuilder;
import org.springframework.batch.core.job.flow.Flow;
import org.springframework.batch.core.scope.context.ChunkContext;
import org.springframework.batch.repeat.RepeatStatus;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@EnableBatchProcessing
public class EmailFlowConfiguration {
@Autowired
private StepBuilderFactory stepBuilderFactory;
@Bean
public Step readSubscribers() {
return this.stepBuilderFactory.get("Read-subscribers")
.tasklet((StepContribution contribution, ChunkContext chunkContext) -> {
System.out.println("Flow Step 1: Reading all the subscribers for this job");
return RepeatStatus.FINISHED;
}).build();
}
@Bean
public Step sendEmail() {
return this.stepBuilderFactory.get("Send-Email")
.tasklet((StepContribution contribution, ChunkContext chunkContext) -> {
System.out.println("Flow Step 2: Sending email to all subscribers");
return RepeatStatus.FINISHED;
}).build();
}
@Bean
public Flow sendNotification() {
FlowBuilder<Flow> flowBuilder = new FlowBuilder<Flow>("notification");
flowBuilder.start(readSubscribers()).next(sendEmail()).end();
return flowBuilder.build();
}
}
Step 4: Define JobConfiguration.
JobConfiguration.java
package com.sample.app.configuration;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.StepContribution;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.job.flow.Flow;
import org.springframework.batch.core.scope.context.ChunkContext;
import org.springframework.batch.repeat.RepeatStatus;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@EnableBatchProcessing
public class JobConfiguration {
@Autowired
private JobBuilderFactory jobBuilderFactory;
@Autowired
private StepBuilderFactory stepBuilderFactory;
@Bean
public Step step1() {
return this.stepBuilderFactory.get("My-Step1")
.tasklet((StepContribution contribution, ChunkContext chunkContext) -> {
System.out.println("Step1: Finished Execution");
return RepeatStatus.FINISHED;
}).build();
}
@Bean
public Step step2() {
return this.stepBuilderFactory.get("My-Step2")
.tasklet((StepContribution contribution, ChunkContext chunkContext) -> {
System.out.println("Step2: Finished Execution");
return RepeatStatus.FINISHED;
}).build();
}
@Bean
public Step step3() {
return this.stepBuilderFactory.get("My-Step3")
.tasklet((StepContribution contribution, ChunkContext chunkContext) -> {
System.out.println("Step3: Finished Execution");
return RepeatStatus.FINISHED;
}).build();
}
@Bean
public Job job(Flow sendNotification) {
return jobBuilderFactory.get("My-Job").start(sendNotification).next(step1()).next(step2()).next(step3()).end().build();
}
}
Step 5: Define main application class.
App.java
package com.sample.app;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@EnableBatchProcessing
@SpringBootApplication
public class App {
public static void main(String[] args) {
SpringApplication.run(App.class, args);
}
}
Step 6: Create application.properties file under src/main/resources folder.
application.properties
logging.level.root=ERROR logging.level.org.hibernate=ERROR ## H2 specific properties spring.h2.console.enabled=true spring.h2.console.path=/h2 spring.datasource.url=jdbc:h2:file:~/db/myOrg.db;DB_CLOSE_ON_EXIT=FALSE;DB_CLOSE_DELAY=-1; spring.datasource.username=krishna spring.datasource.password=password123 spring.datasource.driverClassName=org.h2.Driver ## JPA specific properties # Creates the schema, destroying previous data. spring.jpa.hibernate.ddl-auto=create spring.jpa.database-platform=org.hibernate.dialect.H2Dialect spring.jpa.show-sql=false spring.jpa.properties.hibernate.format_sql=false ## Database connection pooling properties # Number of ms to wait before throwing an exception if no connection is available. spring.datasource.max-wait=10000 # Maximum number of active connections that can be allocated from this pool at the same time. spring.datasource.tomcat.max-active=10 spring.datasource.tomcat.max-idle=5 spring.datasource.tomcat.min-idle=3
Total project structure looks like below.
Run App.java, you will see below messages in console.
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.1.6.RELEASE) Flow Step 1: Reading all the subscribers for this job Flow Step 2: Sending email to all subscribers Step1: Finished Execution Step2: Finished Execution Step3: Finished Execution
You can download complete working application from this link.
https://github.com/harikrishna553/springboot/tree/master/batch/flow-demo
No comments:
Post a Comment