Add builders to simplify remote partitioning setup

Resolves BATCH-2687

* use hard coded constants in docs
* change visibility of method `beanFactory` to public in builders

spring-batch-docs/asciidoc/spring-batch-integration.adoc

@@ -945,7 +945,7 @@ two beans that can be autowired in the application context:
 * `RemoteChunkingMasterStepBuilderFactory`: used to configure the master step
 * `RemoteChunkingWorkerBuilder`: used to configure the remote worker integration flow
 
-These APIs will take care of configuring a number of components as described in the following diagram:
+These APIs take care of configuring a number of components as described in the following diagram:
 
 .Remote Chunking Configuration
 image::{batch-asciidoc}images/remote-chunking-config.png[Remote Chunking Configuration, scaledwidth="80%"]
@@ -1261,3 +1261,92 @@ You must also ensure that the partition `handler` attribute maps to the `partiti
 
 You can find a complete example of a remote partitioning job
 link:$$https://github.com/spring-projects/spring-batch/tree/master/spring-batch-samples#remote-partitioning-sample$$[here].
+
+The `@EnableBatchIntegration` annotation that can be used to simplify a remote
+ partitioning setup. This annotation provides two beans useful for remote partitioning:
+
+* `RemotePartitioningMasterStepBuilderFactory`: used to configure the master step
+* `RemotePartitioningWorkerStepBuilderFactory`: used to configure the worker step
+
+These APIs take care of configuring a number of components as described in the following diagram:
+
+.Remote Partitioning Configuration (with job repository polling)
+image::{batch-asciidoc}images/remote-partitioning-polling-config.png[Remote Partitioning Configuration (with job repository polling), scaledwidth="80%"]
+
+.Remote Partitioning Configuration (with replies aggregation)
+image::{batch-asciidoc}images/remote-partitioning-aggregation-config.png[Remote Partitioning Configuration (with replies aggregation), scaledwidth="80%"]
+
+On the master side, the `RemotePartitioningMasterStepBuilderFactory` allows you to
+configure a master step by declaring:
+
+* the `Partitioner` used to partition data
+* the output channel ("Outgoing requests") to send requests to workers
+* the input channel ("Incoming replies") to receive replies from workers (when configuring replies aggregation)
+* the poll interval and timeout parameters (when configuring job repository polling)
+
+The `MessageChannelPartitionHandler` and the `MessagingTemplate` are not needed to be explicitly configured
+(Those can still be explicitly configured if required).
+
+On the worker side, the `RemotePartitioningWorkerStepBuilderFactory` allows you to configure a worker to:
+
+* listen to requests sent by the master on the input channel ("Incoming requests")
+* call the `handle` method of `StepExecutionRequestHandler` for each request
+* send replies on the output channel ("Outgoing replies") to the master
+
+There is no need to explicitly configure the `StepExecutionRequestHandler` (which can be explicitly configured if required).
+
+The following example shows how to use these APIs:
+
+[source, java]
+----
+@Configuration
+@EnableBatchProcessing
+@EnableBatchIntegration
+public class RemotePartitioningJobConfiguration {
+
+    @Configuration
+    public static class MasterConfiguration {
+
+        @Autowired
+        private RemotePartitioningMasterStepBuilderFactory masterStepBuilderFactory;
+
+        @Bean
+        public Step masterStep() {
+                 return this.masterStepBuilderFactory
+                    .get("masterStep")
+                    .partitioner("workerStep", partitioner())
+                    .gridSize(10)
+                    .outputChannel(outgoingRequestsToWorkers())
+                    .inputChannel(incomingRepliesFromWorkers())
+                    .build();
+        }
+
+        // Middleware beans setup omitted
+
+    }
+
+    @Configuration
+    public static class WorkerConfiguration {
+
+        @Autowired
+        private RemotePartitioningWorkerStepBuilderFactory workerStepBuilderFactory;
+
+        @Bean
+        public Step workerStep() {
+                 return this.workerStepBuilderFactory
+                    .get("workerStep")
+                    .inputChannel(incomingRequestsFromMaster())
+                    .outputChannel(outgoingRepliesToMaster())
+                    .chunk(100)
+                    .reader(itemReader())
+                    .processor(itemProcessor())
+                    .writer(itemWriter())
+                    .build();
+        }
+
+        // Middleware beans setup omitted
+
+    }
+
+}
+----

spring-batch-docs/asciidoc/whatsnew.adoc

@@ -9,7 +9,7 @@
 The Spring Batch 4.1 release adds the following features:
 
 * A new `@SpringBatchTest` annotation to simplify testing batch components
-* A new `@EnableBatchIntegration` annotation to simplify remote chunking configuration
+* A new `@EnableBatchIntegration` annotation to simplify remote chunking and partitioning configuration
 * A new `JsonItemReader` and `JsonFileItemWriter` to support the JSON format
 * Add support for validating items with the Bean Validation API
 
@@ -125,6 +125,55 @@ that uses these new APIs in the
 link:$$https://github.com/spring-projects/spring-batch/tree/master/spring-batch-samples#remote-chunking-sample$$[samples module]
 as well as more details in the <<spring-batch-integration.adoc#remote-chunking,Spring Batch Integration>> chapter.
 
+Just like the remote chunking configuration simplification, this version also
+introduces new APIs to simplify a remote partitioning setup:
+`RemotePartitioningMasterStepBuilder` and `RemotePartitioningWorkerStepBuilder`.
+Those can be autowired in your configuration class if the
+`@EnableBatchIntegration` is present as shown in the following example:
+
+[source, java]
+----
+@Configuration
+@EnableBatchProcessing
+@EnableBatchIntegration
+public class RemotePartitioningAppConfig {
+
+   @Autowired
+   private RemotePartitioningMasterStepBuilderFactory masterStepBuilderFactory;
+
+   @Autowired
+   private RemotePartitioningWorkerStepBuilderFactory workerStepBuilderFactory;
+
+   @Bean
+   public Step masterStep() {
+            return this.masterStepBuilderFactory
+               .get("masterStep")
+               .partitioner("workerStep", partitioner())
+               .gridSize(10)
+               .outputChannel(outgoingRequestsToWorkers())
+               .inputChannel(incomingRepliesFromWorkers())
+               .build();
+   }
+
+   @Bean
+   public Step workerStep() {
+            return this.workerStepBuilderFactory
+               .get("workerStep")
+               .inputChannel(incomingRequestsFromMaster())
+               .outputChannel(outgoingRepliesToMaster())
+               .chunk(100)
+               .reader(itemReader())
+               .processor(itemProcessor())
+               .writer(itemWriter())
+               .build();
+   }
+
+   // Middleware beans setup omitted
+}
+----
+
+You can find more details about these new APIs in the <<spring-batch-integration.adoc#remote-partitioning,Spring Batch Integration>> chapter.
+
 [[whatsNewJson]]
 === JSON support