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INT-1451, INT-588 removed coomment based tx dependencies from the PollerParser, updated documentation with more details on Poller refactoring and other TX stuff to address 588

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Oleg Zhurakousky
2010-09-28 15:57:22 -04:00
parent 9d6d433408
commit d59b40ace7
2 changed files with 43 additions and 3 deletions
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43
src/docbkx/transactions.xml
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@@ -92,7 +92,15 @@
</para>
<para>
Spring Integration provides several hooks to accomplish this.
Spring Integration provides transactional support for Pollers. Pollers are a special case comoponents becouse
we can call receive() within that poller task against a resource that is itself transactional thus including <emphasis>receive()</emphasis>
call in the the boundaries of the Transaction allowing it to be rolled back in case of a task failure. If we were to add the same support
for channels, the added transactions would affect all downstream components starting with that <emphasis>send()</emphasis> call. That is
providing a rather wide scope for transaction demarcation without any strong reason especially when Spring already provides several way to
address transactional needs of any component downstream. However the <emphasis>receive()</emphasis> method being included in a transaction
boundary is the "strong reason" for pollers. 
</para>
<section id="transaction-poller">
@@ -116,6 +124,39 @@
With the above configuration all Message flows initiated by this poller will be transactional. For more information and details on
Poller's transactional configuration please refer to section - <emphasis>21.1.1. Polling and Transactions</emphasis>.
</para>
<para>
There times when besides transaction several more cross cutting concerns needs to be addressed when running Poller. To help with that,
Poller element defines <emphasis>&lt;advice-chain&gt; </emphasis> sub-element which allows you to define a custom chain of Advices
to be applied on the Poller. (see section 4.4 for more details)
In Spring Integration 2.0 Poller went through the major  refactoring effort and is now using proxy mechanism to address transactional
concerns as well as other cross cutting concerns, one of the significant changes evolving from this effort is that we
made <emphasis>&lt;transactional&gt;</emphasis> and <emphasis>&lt;advice-chain&gt;</emphasis> elements mutually exclusive.
The rational behind this is; If you need more then one advice, and one of them is Transaction advice, then you can simply
include it in the <emphasis>&lt;advice-chain&gt;</emphasis> with the same convenience as before but with much more control
since you now have an option to position any advice in the desired order. 
<programlisting language="xml"><![CDATA[<poller max-messages-per-poll="1" fixed-rate="10000">
<advice-chain>
<ref bean="txAdvise"/>
<ref bean="someAotherAdviceBean" />
<beans:bean class="foo.bar.SampleAdvice"/>
</advice-chain>
</poller>
<tx:advice id="txAdvice" transaction-manager="txManager">
<tx:attributes>
<tx:method name="get*" read-only="true"/>
<tx:method name="*"/>
</tx:attributes>
</tx:advice>
]]></programlisting>
As yo can see from the example above, we have provided a very basic XML-based configuration of Spring Transaction advice  - "txAdvice" and
included it within the <emphasis>&lt;advice-chain&gt;</emphasis> defined by the Poller.
And if you only need to address transactional concerns of the Poller, then you can still use <emphasis>&lt;transactional&gt;</emphasis> element
as a convinience.
</para>
</section>
</section>
<section id="transaction-boundaries">