INT-4004: Improve MessageStore Docs

JIRA: https://jira.spring.io/browse/INT-4004

spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/JdbcMessageStore.java

@@ -69,12 +69,14 @@ import org.springframework.util.StringUtils;
  * Implementation of {@link MessageStore} using a relational database via JDBC. SQL scripts to create the necessary
  * tables are packaged as <code>org/springframework/integration/jdbc/schema-*.sql</code>, where <code>*</code> is the
  * target database type.
- *
- * Notice: Starting with Spring Integration 3.0, this class will move to package:
- * <code>org.springframework.integration.jdbc.store</code>.
- *
+ * <p>
+ * Notice: Starting with Spring Integration 5.0, this class will move to package:
+ * {@code org.springframework.integration.jdbc.store}.
+ * <p>
  * If you intend backing a {@link MessageChannel} using a JDBC-based Message Store,
  * please consider using the channel-specific {@link JdbcChannelMessageStore} instead.
+ * This implementation is intended for correlation components (e.g. {@code <aggregator>}),
+ * {@code <delayer>} and similar.
  *
  * @author Dave Syer
  * @author Oleg Zhurakousky

spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/store/JdbcChannelMessageStore.java

@@ -85,10 +85,11 @@ import org.springframework.util.StringUtils;
  * As such, the {@link JdbcChannelMessageStore} uses database specific SQL queries.
  * </p>
  * <p>
- * Contrary to the {@link JdbcMessageStore}, this implementation uses one single
- * database table only. The SQL scripts to create the necessary table are packaged
- * under <code>org/springframework/integration/jdbc/messagestore/channel/schema-*.sql</code>,
- * where <code>*</code> denotes the target database type.
+ * Contrary to the {@link JdbcMessageStore}, this implementation uses a single database table,
+ * optimized to operate like a queue.
+ * The SQL scripts for creating the table are packaged
+ * under {@code org/springframework/integration/jdbc/messagestore/channel/schema-*.sql},
+ * where {@code *} denotes the target database type.
  * </p>
  *
  * @author Gunnar Hillert

src/reference/asciidoc/message-store.adoc

@@ -10,7 +10,7 @@ RDBMS).
 
 Spring Integration provides support for the _Message Store_ pattern by a) defining a `org.springframework.integration.store.MessageStore` strategy interface, b) providing several implementations of this interface, and c) exposing a `message-store` attribute on all components that have the capability to buffer messages so that you can inject any instance that implements the `MessageStore` interface.
 
-Details on how to configure a specific _Message Store_ implementation and/or how to inject a `MessageStore` implementation into a specific buffering component are described throughout the manual (see the specific component, such as _QueueChannel_, _Aggregator_, _Resequencer_ etc.), but here are a couple of samples to give you an idea:
+Details on how to configure a specific _Message Store_ implementation and/or how to inject a `MessageStore` implementation into a specific buffering component are described throughout the manual (see the specific component, such as <<channel-configuration-queuechannel,_QueueChannel_>>, <<aggregator,_Aggregator_>>, <<delayer,_Delayer_>> etc.), but here are a couple of samples to give you an idea:
 
 QueueChannel
 [source,xml]
@@ -62,7 +62,7 @@ For more information, refer to the <<header-enricher>>.
 
 _Spring Integration 4.0_ introduced two new interfaces `ChannelMessageStore` - to implement operations specific for `QueueChannel` s, `PriorityCapableChannelMessageStore` - to mark `MessageStore` implementation to be used for `PriorityChannel` s and to provide _priority_ order for persisted Messages.
 The real behaviour depends on implementation.
-The Framework provides these implementations, which can be used as a persistent `MessageStore` for `PriorityChannel`:
+The Framework provides these implementations, which can be used as a persistent `MessageStore` for `QueueChannel` and `PriorityChannel`:
 
 * <<redis-cms>>
 * <<mongodb-priority-channel-message-store>>