ElasticJob-Lite and ElasticJob-Cloud provide a unified job interface, developers need to develop business jobs only once, and then they can be deployed to different environments according to different configurations and deployments.

ElasticJob has two kinds of job types: Class-based job and Type-based job. Class-based jobs require developers to weave business logic by implementing interfaces; Type-based jobs don’t need coding, just need to provide the corresponding configuration.

The method parameter shardingContext of the class-based job interface contains job configuration, slice and runtime information. Through methods such as getShardingTotalCount(), getShardingItem(), user can obtain the total number of shards, the serial number of the shards running on the job server, etc.

ElasticJob provides two class-based job types which are Simple and Dataflow; and also provides a type-based job which is Script. Users can extend job types by implementing the SPI interface.

Simple Job

It means simple implementation, without any encapsulation type. Need to implement SimpleJob interface. This interface only provides a single method for coverage, and this method will be executed periodically. It is similar to Quartz’s native interface, but provides functions such as elastic scaling and slice.

public class MyElasticJob implements SimpleJob {
    @Override
    public void execute(ShardingContext context) {
        switch (context.getShardingItem()) {
            case 0: 
                // do something by sharding item 0
                break;
            case 1: 
                // do something by sharding item 1
                break;
            case 2: 
                // do something by sharding item 2
                break;
            // case n: ...
        }
    }
}

Dataflow Job

For processing data flow, need to implement DataflowJob interface. This interface provides two methods for coverage, which are used to fetch (fetchData) and process (processData) data.

public class MyElasticJob implements DataflowJob<Foo> {
    @Override
    public List<Foo> fetchData(ShardingContext context) {
        switch (context.getShardingItem()) {
            case 0: 
                List<Foo> data = // get data from database by sharding item 0
                return data;
            case 1: 
                List<Foo> data = // get data from database by sharding item 1
                return data;
            case 2: 
                List<Foo> data = // get data from database by sharding item 2
                return data;
            // case n: ...
        }
    }
    @Override
    public void processData(ShardingContext shardingContext, List<Foo> data) {
        // process data
        // ...
    }
}

Streaming

Streaming can be enabled or disabled through the property streaming.process.

If streaming is enabled, the job will stop fetching data only when the return value of the fetchData method is null or the collection is empty, otherwise the job will continue to run; If streaming is disabled, the job will execute the fetchData and processData methods only once during each job execution, and then the job will be completed immediately.

If use the streaming job to process data, it is recommended to update its status after the processData method being executed, to avoid being fetched again by the method fetchData, so that the job never stops.

Script job

Support all types of scripts such as shell, python, perl. The script to be executed can be configured through the property script.command.line, without coding. The script path can contain parameters, after the parameters are passed, the job framework will automatically append the last parameter as the job runtime information.

The script example is as follows:

#!/bin/bash
echo sharding execution context is $*

When the job runs, it will output:

sharding execution context is {"jobName":"scriptElasticDemoJob","shardingTotalCount":10,"jobParameter":"","shardingItem":0,"shardingParameter":"A"}

HTTP job (Since 3.0.0-beta)

The http information to be requested can be configured through the properties of http.url, http.method, http.data, etc. Sharding information is transmitted in the form of Header, the key is shardingContext, and the value is in json format.

public class HttpJobMain {
    public static void main(String[] args) {
        new ScheduleJobBootstrap(regCenter, "HTTP", JobConfiguration.newBuilder("javaHttpJob", 1)
                .setProperty(HttpJobProperties.URI_KEY, "http://xxx.com/execute")
                .setProperty(HttpJobProperties.METHOD_KEY, "POST")
                .setProperty(HttpJobProperties.DATA_KEY, "source=ejob")
                .cron("0/5 * * * * ?").shardingItemParameters("0=Beijing").build()).schedule();
    }
}

@Controller
@Slf4j
public class HttpJobController {
    @RequestMapping(path = "/execute", method = RequestMethod.POST)
    public void execute(String source, @RequestHeader String shardingContext) {
        log.info("execute from source : {}, shardingContext : {}", source, shardingContext);
    }
}

When the job runs, it will output：

execute from source : ejob, shardingContext : {"jobName":"scriptElasticDemoJob","shardingTotalCount":3,"jobParameter":"","shardingItem":0,"shardingParameter":"Beijing"}