INT-3339: Add priority to the JdbcChannelMS
JIRA: https://jira.spring.io/browse/INT-3339 INT-3339: Improve `priority` logic INT-3339: Add `MESSAGE_SEQUENCE` stuff INT-3339: Docs INT-3339: Polishing and PR comments INT-3339 Polishing Fix Oracle Test Case. Doc polishing.
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Artem Bilan
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Gary Russell
Gary Russell
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3f40c40641
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64a7a7e021
@@ -566,15 +566,16 @@ payload to an Integer.
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<code>message-store</code> attribute as shown in the next example.
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<programlisting language="xml"><![CDATA[<int:channel id="dbBackedChannel">
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<int:queue message-store="messageStore"/>
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<int:queue message-store="channelStore"/>
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</int:channel>
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<int-jdbc:message-store id="messageStore" data-source="someDataSource"/>]]></programlisting>
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<bean id="channelStore" class="o.s.i.jdbc.store.JdbcChannelMessageStore">
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<property name="dataSource" ref="dataSource"/>
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<property name="channelMessageStoreQueryProvider" ref="queryProvider"/>
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</bean>]]></programlisting>
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The above example also shows that <classname>JdbcMessageStore</classname> can be configured with the namespace support
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provided by the Spring Integration JDBC module. All you need to do is inject any <classname>javax.sql.DataSource</classname>
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instance. The Spring Integration JDBC module also provides schema DDL for most popular databases. These schemas are located in
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the <emphasis>org.springframework.integration.jdbc</emphasis> package of that module (spring-integration-jdbc).
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The Spring Integration JDBC module also provides schema DDL for a number of popular databases. These schemas are located in
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the <emphasis>org.springframework.integration.jdbc.store.channel</emphasis> package of that module (spring-integration-jdbc).
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<important>
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One important feature is that with any transactional persistent store (e.g., JdbcChannelMessageStore), as long as the poller has a transaction configured,
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@@ -662,9 +663,12 @@ payload to an Integer.
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<para>
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Since <emphasis>version 4.0</emphasis>, the <code>priority-channel</code> child element supports
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the <code>message-store</code> option (<code>comparator</code> is not allowed in that case).
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The message store must be a <interfacename>ChannelPriorityMessageStore</interfacename> and, in this
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The message store must be a <interfacename>PriorityCapableChannelMessageStore</interfacename> and, in this
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case, the namespace parser will declare a <classname>QueueChannel</classname> instead of
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a <classname>PriorityChannel</classname>. See <xref linkend="channel-configuration-queuechannel"/>.
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a <classname>PriorityChannel</classname>. Implementations of the
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<classname>PriorityCapableChannelMessageStore</classname> are currently provided for <code>Redis</code>
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and <code>JDBC</code>.
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See <xref linkend="channel-configuration-queuechannel"/>.
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</para>
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</section>
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<section id="channel-configuration-rendezvouschannel">
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@@ -420,16 +420,12 @@
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<section id="jdbc-message-store-channels">
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<title>Backing Message Channels</title>
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<para>
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If you intent backing <emphasis>Message Channels</emphasis> using JDBC,
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If you intend backing <emphasis>Message Channels</emphasis> using JDBC,
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it is recommended to use the provided <classname>JdbcChannelMessageStore</classname>
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implementation instead. It can only be used in conjuntion
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implementation instead. It can only be used in conjunction
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with <emphasis>Message Channels</emphasis>.
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</para>
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<note>
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The provided <classname>JdbcChannelMessageStore</classname>
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implementation is available since <emphasis>Spring Integration 2.2.</emphasis>.
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</note>
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<para><emphasis>Supported Database</emphasis></para>
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<para><emphasis role="bold">Supported Databases</emphasis></para>
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<para>
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The <classname>JdbcChannelMessageStore</classname> uses database specific
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SQL queries to retrieve messages from the database. Therefore, users must
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@@ -451,19 +447,27 @@
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the <classname>AbstractChannelMessageStoreQueryProvider</classname>
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class and provide your own custom queries.
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</para>
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<para>
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Since <emphasis>version 4.0</emphasis>, the <code>MESSAGE_SEQUENCE</code> column has been
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added to the table to ensure first-in-first-out (FIFO) queueing even when messages are
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stored in the same millisecond.
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</para>
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<important>
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<para>
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Generally it is not recommened to use a relational database for the
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Generally it is not recommended to use a relational database for the
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purpose of queuing. Instead, if possible, consider using either JMS or
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AMQP, for which message store implementation are provided as well. For
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AMQP backed channels instead. For
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further reference please see the following resources:
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</para>
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<itemizedlist>
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<listitem><ulink url="https://www.engineyard.com/blog/2011/5-subtle-ways-youre-using-mysql-as-a-queue-and-why-itll-bite-you/">5 subtle ways you’re using MySQL as a queue, and why it’ll bite you</ulink></listitem>
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<listitem><ulink url="http://mikehadlow.blogspot.com/2012/04/database-as-queue-anti-pattern.html">The Database As Queue Anti-Pattern</ulink></listitem>
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<listitem><ulink url=
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"https://www.engineyard.com/blog/2011/5-subtle-ways-youre-using-mysql-as-a-queue-and-why-itll-bite-you/"
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>5 subtle ways you’re using MySQL as a queue, and why it’ll bite you</ulink>.</listitem>
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<listitem><ulink url="http://mikehadlow.blogspot.com/2012/04/database-as-queue-anti-pattern.html"
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>The Database As Queue Anti-Pattern</ulink>.</listitem>
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</itemizedlist>
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</important>
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<para><emphasis>Concurrent Polling</emphasis></para>
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<para><emphasis role="bold">Concurrent Polling</emphasis></para>
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<para>
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When polling a <emphasis>Message Channel</emphasis>, you have the option
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to configure the associated <classname>Poller</classname> with a
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@@ -520,7 +524,46 @@
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<int:channel id="outputChannel" />
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…]]></programlisting>
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<para>
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<emphasis role="bold">Priority Channel</emphasis>
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<para>
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Starting with <emphasis>version 4.0</emphasis>, the <classname>JdbcChannelMessageStore</classname>
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implements <interfacename>PriorityCapableChannelMessageStore</interfacename> and provides the
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<code>priorityEnabled</code> option allowing it to be used as a <code>message-store</code>
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reference for <code>priority-queue</code>s. For this purpose, the <code>INT_CHANNEL_MESSAGE</code>
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has a <code>MESSAGE_PRIORITY</code> column to store the value of <code>PRIORITY</code> Message header.
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In addition, a new <code>MESSAGE_SEQUENCE</code> column is also provided to achieve a robust first-in-first-out
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(FIFO) polling mechanism, even when multiple messages are stored with the same priority
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in the same millisecond. Messages are polled (selected) from the database with
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<code>order by MESSAGE_PRIORITY DESC NULLS LAST, CREATED_DATE, MESSAGE_SEQUENCE</code>.
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</para>
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<note>
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<para>
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It's not recommended to use the same <classname>JdbcChannelMessageStore</classname> bean
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for priority and non-priority queue channel, because <code>priorityEnabled</code> option applies to the
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entire store and proper FIFO queue semantics will not be retained for the queue channel.
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However the same <code>INT_CHANNEL_MESSAGE</code> table, and even <code>region</code>, can be used for both
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<classname>JdbcChannelMessageStore</classname> types. To configure that scenario, simply
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extend one message store bean from the other:
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</para>
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</note>
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<programlisting language="xml"><![CDATA[<bean id="channelStore" class="o.s.i.jdbc.store.JdbcChannelMessageStore">
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<property name="dataSource" ref="dataSource"/>
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<property name="channelMessageStoreQueryProvider" ref="queryProvider"/>
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</bean>
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<int:channel id="queueChannel">
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<int:queue message-store="store"/>
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</int:channel>
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<bean id="priorityStore" parent="channelStore">
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<property name="priorityEnabled" value="true"/>
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</bean>
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<int:channel id="priorityChannel">
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<int:priority-queue message-store="priorityStore"/>
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</int:channel>]]></programlisting>
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</para>
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</section>
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<section>
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<title>Initializing the Database</title>
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@@ -262,5 +262,14 @@
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<xref linkend="sftp-inbound"/>.
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</para>
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</section>
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<section id="4.0-jdbc-cs">
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<title>JdbcChannelMessageStore and PriorityChannel</title>
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<para>
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The <classname>JdbcChannelMessageStore</classname> now implements
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<interfacename>PriorityCapableChannelMessageStore</interfacename>, allowing it to be used as
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a <code>message-store</code> reference for <code>priority-queue</code>s.
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For more information, see <xref linkend="jdbc-message-store-channels"/>.
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</para>
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</section>
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</section>
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</chapter>
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