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From conflue...@apache.org
Subject [CONF] Apache Camel > Camel 3.0 - Roadmap
Date Fri, 09 Mar 2012 08:58:00 GMT
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    <h2><a href="https://cwiki.apache.org/confluence/display/CAMEL/Camel+3.0+-+Roadmap">Camel
3.0 - Roadmap</a></h2>
    <h4>Page <b>edited</b> by             <a href="https://cwiki.apache.org/confluence/display/~davsclaus">Claus
Ibsen</a>
    </h4>
        <br/>
                         <h4>Changes (1)</h4>
                                 
    
<div id="page-diffs">
                    <table class="diff" cellpadding="0" cellspacing="0">
    
            <tr><td class="diff-snipped" >...<br></td></tr>
            <tr><td class="diff-unchanged" > <br>We could move {{ThreadPoolProfile}}
from {{org.apache.camel.spi}} to {{org.apache.camel}} and have it in the root package.  <br></td></tr>
            <tr><td class="diff-added-lines" style="background-color: #dfd;">
<br>h4. Tighten up onException <br> <br>We should consider tighten up the
onException DSL a bit, for example to make it more clear that if you have processing steps
in there, they only occur after the message has been exhausted. So maybe we need to have a
onExhausted to make this clear <br> <br>{code} <br>onException(IOException.class).maximumRedeliveries(3)
<br>  .onExhausted().handled(true).to(&quot;log:ignoreMe&quot;); <br>{code}
<br> <br>So in this example its only after the 3 failed redeliveries, then its
exhausted, and then we handle the message and route it to a log where we ignore the message.
<br> <br>Also currently you can do this: <br>{code} <br>onException(IOException.class).maximumRedeliveries(3)
<br>  .handled(true); <br>{code} <br> <br>Which will handle the message
and after this let the error handler deal with the message. See [CAMEL-5059|https://issues.apache.org/jira/browse/CAMEL-5069].
<br>We should in this case use a NoopProcessor so the message is handled, but the regular
error handler does not react. Then its consistent. <br>However we have not changed this
in Camel 2.x to keep backwards compatibility. <br> <br>Likewise there has been
ideas to move onRedeliverRef to &lt;redeliveryPolicy&gt; as currently its to be configured
outside the policy. <br>It may make more sense to move onRedeliverRef to the policy
to keep it together.  <br></td></tr>
    
            </table>
    </div>                            <h4>Full Content</h4>
                    <div class="notificationGreySide">
        <h2><a name="Camel3.0-Roadmap-Camel3.0roadmap"></a>Camel 3.0 roadmap</h2>

<p>This is a roadmap which details the overall and major goals for Camel 3.0. Fell free
to discuss this at the Camel <a href="/confluence/display/CAMEL/Mailing+Lists" title="Mailing
Lists">Mailing Lists</a> if you have ideas or feedback.</p>

<p>The Camel PMC conducted a <a href="/confluence/download/attachments/23333649/camel-survey-2010.pdf?version=1&amp;modificationDate=1291051405000">survey
in Oct 2010</a> to get a better understanding of how Camel is used and what the priorities
for Camel 3.0 should be.</p>

<div class='panelMacro'><table class='warningMacro'><colgroup><col width='24'><col></colgroup><tr><td
valign='top'><img src="/confluence/images/icons/emoticons/forbidden.gif" width="16"
height="16" align="absmiddle" alt="" border="0"></td><td><b>Nothing is
committed/confirmed</b><br />The items listed on this wiki page is just <b>ideas</b>
for the roadmap. Anything is subject for change.<br/>
Speak up if you want to ensure a feature is on the roadmap, or if you have new ideas etc.

<p>When development of Camel 3.0 starts we will update status here which items have
been implemented in the source code, and which have been discarded/deferred etc.</p></td></tr></table></div>

<h3><a name="Camel3.0-Roadmap-ClearerArchitectureofCamelCore"></a>Clearer
Architecture of Camel Core</h3>

<p>Goals:</p>
<ul>
	<li>The camel components should know as little as possible about camel core</li>
	<li>The classes needed to setup camel should be separate from the things needed at
run time</li>
</ul>


<p>So why should this be important? Currently components depend on camel-core as a whole
and there are no further rules which classes the components should use and which classes should
be private to core. Even classes from the impl package are needed. So this means that any
refactoring we do in camel core could affect all components. As camel is growing steadily
this can become quite problematic.</p>

<p>Split camel-core into three parts:</p>

<p>api, builder, impl</p>

<p>These should be structured in a way that these big building blocks do not have cyclic
dependencies. Any other cycles can be ignored in this step.</p>

<p>Allowed depdencies ( "-&gt;" means may use, may depend on):</p>

<ul>
	<li>* -&gt; api</li>
	<li>end user config code -&gt; builder</li>
	<li>builder -&gt; impl</li>
</ul>


<h4><a name="Camel3.0-Roadmap-Definescopeandrulesforcamelcorepackages"></a>Define
scope and rules for camel-core packages</h4>

<p>In extension to the previous paragraph each camel package should have a clear scope
that defines what to put in the package and what not. There should be rules that define what
dependencies are allowed for classes in a package. The minimum goal is to guarantee that by
following the rules dependency cycles can not happen. Additionally the rules should minimize
dependencies between packages to achieve loose coupling between packages and high coherence
inside a package.</p>

<h4><a name="Camel3.0-Roadmap-Routingengineoptimization"></a>Routing engine
optimization</h4>

<p>The internal routing engine should be optimized. See more details at <a href="/confluence/display/CAMEL/Camel+2.x+Speed+optimizations"
title="Camel 2.x Speed optimizations">Camel 2.x Speed optimizations</a>.</p>

<h3><a name="Camel3.0-Roadmap-Moreflexibleroutesatruntime"></a>More flexible
routes at runtime</h3>

<p>When routes is added in Camel 2.x architecture, global cross cutting concerns such
as error handlers, interceptors, onCompletion etc. is applied when the route is added. We
need to separate this and have those applied during routing. The <tt>Channel</tt>
needs to do this and therefore it must be more dynamic than its currently is. And we need
to enlist the various global cross cutting concerns by their xxxDefintions in the CamelContext,
so we can access them at any time. This allows end users also much more easily to add/remove
interceptors, error handlers and whatnot at runtime. And it makes it much easier to add routes
generated from JAXB or other sources, as we don't need to prepare or anyhow <em>mold</em>
the <tt>RouteDefinition</tt> given. See ticket <a href="https://issues.apache.org/activemq/browse/CAMEL-3024"
class="external-link" rel="nofollow">CAMEL-3024</a> for some details. </p>

<h4><a name="Camel3.0-Roadmap-RouteinitializationlogicforJavaDSLandXMLDSLs"></a>Route
initialization logic for Java DSL and XML DSLs</h4>

<p>The Java DSL does its route initialization slightly a bit different than the XML
DSLs, due the nature of it, and the fact the fluent builders can do additional logic, which
the JAXB model of XML DSLs does not. We should align the initialization logic so Java DSL
and XML DSLs does the same thing. They setup the pure model at first. So the configure method
in the RouteBuilder should setup the model as the XML DSL would do. Then the prepare route
logic which follows could be the same in all cases. This would also allow us to ensure when
people use multiple RouteBuilder classes in Java DSL, then context scoped onException, interceptors
is applied for all RouteBuilders.</p>

<h4><a name="Camel3.0-Roadmap-AddOnException%2CInterceptor%2Cetc.toJAXBmodelforaCamelContextDefinition"></a>Add
OnException, Interceptor, etc. to JAXB model for a CamelContextDefinition</h4>

<p>Configuring context scoped onException, interceptors etc. is woven into the RouteDefinition
as part of the route initialization logic. When we have a dynamic routing engine (see above)
that can at runtime support this without the need for woven into the routes. Then we should
also ensure the context scoped onException, interceptors etc. is available in a CamelContextDefinition.
This ensures the models is always 100% kept as it was provided, and we can fully export the
model to XML and other languages (having a supported render).</p>

<h4><a name="Camel3.0-Roadmap-Tightenuproutedefinitions"></a>Tighten up
route definitions</h4>

<p>Currently cross cutting concerns such as error handlers, interceptors, onCompletion
etc. can be define anywhere in the route. We should tighten this up and only allow this to
be configured in the start of the route. This also ensures when end users use code assistance
in their route development, the IDE will not popup a big list which includes these cross cutting
concerns. See also next note. (ProcessorDefinition will therefore be trimmed)</p>

<h4><a name="Camel3.0-Roadmap-Supportforasynchronoustransactions"></a>Support
for asynchronous transactions</h4>

<p>When using the asynchronous routing engine it would be desirable of transactional
context could be propagated to the new threads.<br/>
This requires the TX manager supports suspend/resume on the TX. G.Nodet have worked a bit
on this. See <a href="https://issues.apache.org/activemq/browse/CAMEL-2902" class="external-link"
rel="nofollow">CAMEL-2902</a>. Also see <a href="https://issues.apache.org/activemq/browse/CAMEL-2729"
class="external-link" rel="nofollow">CAMEL-2729</a>.</p>

<p>With the <a href="/confluence/display/CAMEL/Asynchronous+Routing+Engine" title="Asynchronous
Routing Engine">Asynchronous Routing Engine</a> it would be great if we could support
asynchronous transaction as well. See <a href="https://issues.apache.org/activemq/browse/CAMEL-2729"
class="external-link" rel="nofollow">CAMEL-2729</a> and <a href="https://issues.apache.org/activemq/browse/CAMEL-2902"
class="external-link" rel="nofollow">CAMEL-2902</a></p>

<h4><a name="Camel3.0-Roadmap-Remove@deprecated"></a>Remove @deprecated</h4>

<p>@deprecated features, methods, etc. is to be removed.</p>

<h4><a name="Camel3.0-Roadmap-Streamcaching"></a>Stream caching</h4>

<p>We could add support for using <a href="/confluence/display/CAMEL/HawtDB" title="HawtDB">HawtDB</a>
as the persistent store for streams which overflow to disk store.</p>

<h4><a name="Camel3.0-Roadmap-EIP"></a>EIP</h4>

<p>The <a href="/confluence/display/CAMEL/Resequencer" title="Resequencer">Resequencer</a>
EIP currently doesn't support persistence, we could introduce this and let it leverage <a
href="/confluence/display/CAMEL/HawtDB" title="HawtDB">HawtDB</a> such as we did
with the <a href="/confluence/display/CAMEL/Aggregator2" title="Aggregator2">Aggregator2</a>
EIP.</p>

<h4><a name="Camel3.0-Roadmap-ScheduleinDSL"></a>Schedule in DSL</h4>

<p>We could consider adding DSL syntax sugar for scheduling routes. For example currently
you have to use <a href="/confluence/display/CAMEL/Quartz" title="Quartz">Quartz</a>
or a <tt>ScheduledPollingConsumer</tt> which has the <tt>delay</tt>
option. We could add DSL which has something like:</p>

<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
schedule().every(5).minute().pollFrom(<span class="code-quote">"xxx"</span>).to(<span
class="code-quote">"yyyy"</span>)
</pre>
</div></div>

<p>The hard part is to come up with a good DSL syntax. We can look at <a href="/confluence/display/CAMEL/BAM"
title="BAM">BAM</a> and see what we got there as well.</p>

<p>The DSL should support both cron and non cron based, eg <a href="/confluence/display/CAMEL/Quartz"
title="Quartz">Quartz</a>, <a href="/confluence/display/CAMEL/Spring" title="Spring">Spring</a>
(spring 3 has cron) and regular JDK timers.</p>

<h4><a name="Camel3.0-Roadmap-Fixrouteswithmultipleinputs"></a>Fix routes
with multiple inputs</h4>

<p>The current implementation of routes with multiple inputs is to clone the route,
which means you essentially got 2+ routes if a route has multiple inputs. However routes with
multiple inputs is seldom used. The correct implementation is to only create one route but
have multiple input consumers. This change will require a bit of change in current code as
it relies on the <em>only 1 input consumer</em> on the route.</p>

<h3><a name="Camel3.0-Roadmap-UptodateScalaDSL"></a>Up-to-date Scala DSL</h3>

<p>The Scala DSL is slightly out of date as we have improved the DSL a bit here and
there. We should check the gap and ensure the Scala is up-to-date.</p>

<h4><a name="Camel3.0-Roadmap-AdvancedScalasupport"></a>Advanced Scala support</h4>

<p>A proposal for advanced Scala support is <a href="https://github.com/krasserm/scalaz-camel/wiki"
class="external-link" rel="nofollow">scalaz-camel</a> which is an alternative to
Camel's existing Scala DSL.</p>

<h4><a name="Camel3.0-Roadmap-MoreEIPsas@annotations"></a>More EIPs as @annotations</h4>

<p>Currently its only the <a href="/confluence/display/CAMEL/Routing+Slip" title="Routing
Slip">Routing Slip</a>, <a href="/confluence/display/CAMEL/Recipient+List" title="Recipient
List">Recipient List</a> and <a href="/confluence/display/CAMEL/Dynamic+Router"
title="Dynamic Router">Dynamic Router</a> which are avail as @annotation as well.
We could add more <a href="/confluence/display/CAMEL/EIP" title="EIP">EIP</a>s
as annotations such as <a href="/confluence/display/CAMEL/Splitter" title="Splitter">Splitter</a>.<br/>
And also maybe annotations for <tt>AggregationStrategy</tt> to make this less
Camel API dependent, so you can use a plain POJO for that.</p>

<h4><a name="Camel3.0-Roadmap-Unifiedstatistics"></a>Unified statistics</h4>

<p>Currently the performance statistics is only avail when using JMX. We should allow
those stats to be enabled regardless if JMX is enabled or not. Then we can use those stats
from the web console. This also allows to expose those stats in the cloud where JMX is often
not possible to be used.</p>

<p>In the <tt>camel-jpa</tt> component we could offer JPA annotated entities
with the performance status (just as we do for the tracer). Then end user can more easily
use that if they want the stats to be persisted in a database using <a href="/confluence/display/CAMEL/JPA"
title="JPA">JPA</a>.</p>

<h4><a name="Camel3.0-Roadmap-SEDA%2FVMcomponentstoleverageasyncroutingengine"></a>SEDA/VM
components to leverage async routing engine</h4>

<p>This allows to use non blocking request-reply over <a href="/confluence/display/CAMEL/SEDA"
title="SEDA">SEDA</a> and <a href="/confluence/display/CAMEL/VM" title="VM">VM</a>.
The reason why we havent converted in 2.4 is it causes a bigger API breakage. </p>

<h4><a name="Camel3.0-Roadmap-camelosgitest"></a>camel-osgi-test</h4>

<p>When testing your Camel apps with OSGi you may use PaxExam for that. We should create
a test kit for osgi, like we have camel-test for regular junit testing. The test kit should
make it easy for end users to have their apps tested with OSGi. We already have pieces in
the <tt>tests/camel-itest-osgi</tt>. We just need to clean and shape it up so
its ready for end users as well. And of course add documentation as well.<br/>
And then we should use it in <tt>camel-itest-osgi</tt> of course.</p>

<h4><a name="Camel3.0-Roadmap-REST"></a>REST</h4>
<p>We already have REST support with <a href="/confluence/display/CAMEL/CXFRS" title="CXFRS">CXFRS</a>
and <a href="/confluence/display/CAMEL/Restlet" title="Restlet">Restlet</a> but
it can be better. We should make sure those components is dead easy to use and you can invoke
REST services in one line of code etc. And we should make more examples and tidy up the <a
href="/confluence/display/CAMEL/CXFRS" title="CXFRS">CXFRS</a> documentation.</p>

<h4><a name="Camel3.0-Roadmap-Moreloadtests"></a>More load tests</h4>
<p>More load tests for frequently used Camel components (jetty, jms ...) and camel-core.</p>
<ul>
	<li>Ensure correct behaviour under load</li>
	<li>Source for performance numbers (throughput etc).</li>
	<li>Detection of memory leaks</li>
	<li>Detection of performance decreases after refactorings</li>
	<li>...</li>
</ul>


<h4><a name="Camel3.0-Roadmap-Fasterunittests"></a>Faster unit tests</h4>

<p>Decreasing the total time for our complete build from more than 2 hours at present.
This means in fact we have to decrease the time of our unit tests.</p>

<h4><a name="Camel3.0-Roadmap-OSGienhancements"></a>OSGi enhancements</h4>
<ul>
	<li>create a single type converter registry available as OSGi service to all bundles
serving as a single registry to lookup converters or to add/remove converters from custom
bundles</li>
</ul>


<h4><a name="Camel3.0-Roadmap-Easiercommit%2Frollbackforcomponentdevelopers"></a>Easier
commit/rollback for component developers</h4>

<p>Maybe expose some interface having commit / rollback methods to make it easier for
component developers to implement custom logic. Currently they may not know about <a href="/confluence/display/CAMEL/OnCompletion"
title="OnCompletion">OnCompletion</a> and how to use <tt>UnitOfWork</tt>
on Exchange to do this today.</p>

<h4><a name="Camel3.0-Roadmap-Unifyuri%2Fref"></a>Unify uri/ref</h4>

<p>Instead of having both uri and ref for endpoints, we should unify this and only use
uri. If people want to use ref, then they can do that using "ref:xx" as an uri. This would
simplify code as we dont have to check for either one.</p>

<h4><a name="Camel3.0-Roadmap-LessSpringdependencies"></a>Less Spring dependencies</h4>
<p><b>DONE in Camel 2.9</b></p>

<p>In camel-core we use the Spring JMX annotations to more easily enlist our MBeans.
We should move that logic to camel-spring. And introduce a Camel specific annotations to replace
those. For example ActiveMQ does that. This allows us to use camel-core with JMX without any
spring JARs at all. End users can still use the Spring JMX annotations in their custom code
/ components. They just need camel-spring on the classpath.</p>

<p>Likewise we should move the ResourceEndpoint from camel-spring to camel-core. This
ensures that resource loading on classpath works with Camel as we can leverage the ClassResolver.
For example OSGi blueprint does not work with the Spring ResourceEndpoint. Also this ensures
the components that uses ResourceEndpoint will no longer be dependent on Spring.</p>

<p>Then we are down to have Spring JAR dependency in: camel-jms and camel-mail.</p>

<h4><a name="Camel3.0-Roadmap-IntroduceCamelJMXannotations"></a>Introduce
Camel JMX annotations</h4>
<p><b>DONE in Camel 2.9</b></p>

<p>See above about less Spring dependency.</p>

<h4><a name="Camel3.0-Roadmap-RefactorUnitOfWork"></a>Refactor UnitOfWork</h4>

<p>The implementation of DefaultUnitOfWork seems to have transformed itself into a to
broad concern where unit of work is doing a bit more work than the transactional aspect that
ties to its name.<br/>
Maybe this implementation should be named ExchangeContext and we can introduce a simpler UnitOfWork
concept. This would also allow us to refactor the SubUnitOfWork into a general parent/child
unit of work concept.<br/>
However this requires API changes and thus is best kept for Camel 3.0</p>

<h4><a name="Camel3.0-Roadmap-ImprovementstoThreadPoolProfileforthreadmanagement"></a>Improvements
to ThreadPoolProfile for thread management</h4>

<p>We could move <tt>ThreadPoolProfile</tt> from <tt>org.apache.camel.spi</tt>
to <tt>org.apache.camel</tt> and have it in the root package. </p>

<h4><a name="Camel3.0-Roadmap-TightenuponException"></a>Tighten up onException</h4>

<p>We should consider tighten up the onException DSL a bit, for example to make it more
clear that if you have processing steps in there, they only occur after the message has been
exhausted. So maybe we need to have a onExhausted to make this clear</p>

<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
onException(IOException.class).maximumRedeliveries(3)
  .onExhausted().handled(<span class="code-keyword">true</span>).to(<span class="code-quote">"log:ignoreMe"</span>);
</pre>
</div></div>

<p>So in this example its only after the 3 failed redeliveries, then its exhausted,
and then we handle the message and route it to a log where we ignore the message.</p>

<p>Also currently you can do this:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
onException(IOException.class).maximumRedeliveries(3)
  .handled(<span class="code-keyword">true</span>);
</pre>
</div></div>

<p>Which will handle the message and after this let the error handler deal with the
message. See <a href="https://issues.apache.org/jira/browse/CAMEL-5069" class="external-link"
rel="nofollow">CAMEL-5059</a>.<br/>
We should in this case use a NoopProcessor so the message is handled, but the regular error
handler does not react. Then its consistent.<br/>
However we have not changed this in Camel 2.x to keep backwards compatibility.</p>

<p>Likewise there has been ideas to move onRedeliverRef to &lt;redeliveryPolicy&gt;
as currently its to be configured outside the policy.<br/>
It may make more sense to move onRedeliverRef to the policy to keep it together. </p>

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