Modified: websites/production/camel/content/zookeeper.html
==============================================================================
--- websites/production/camel/content/zookeeper.html (original)
+++ websites/production/camel/content/zookeeper.html Wed Mar 12 17:19:36 2014
@@ -86,103 +86,40 @@
<tbody>
<tr>
<td valign="top" width="100%">
-<div class="wiki-content maincontent"><h2
id="Zookeeper-ZooKeeper">ZooKeeper</h2>
-
-<p><strong>Available as of Camel 2.9</strong></p>
-
-<p>The ZooKeeper component allows interaction with a <a shape="rect"
class="external-link" href="http://hadoop.apache.org/zookeeper/";>ZooKeeper</a>
cluster and exposes the following features to Camel:</p>
-
-<ol><li>Creation of nodes in any of the ZooKeeper create modes.</li><li>Get
and Set the data contents of arbitrary cluster nodes.</li><li>Create and
retrieve the list the child nodes attached to a particular node.</li><li>A
Distributed <a shape="rect" href="routepolicy.html">RoutePolicy</a> that
leverages a Leader election coordinated by ZooKeeper to determine if exchanges
should get processed.</li></ol>
-
-
-<p>Maven users will need to add the following dependency to their
<code>pom.xml</code> for this component:</p>
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: xml; gutter: false"
type="syntaxhighlighter"><![CDATA[
-<dependency>
+<div class="wiki-content maincontent"><h2
id="Zookeeper-ZooKeeper">ZooKeeper</h2><p><strong>Available as of Camel
2.9</strong></p><p>The ZooKeeper component allows interaction with a <a
shape="rect" class="external-link"
href="http://hadoop.apache.org/zookeeper/";>ZooKeeper</a> cluster and exposes
the following features to Camel:</p><ol><li>Creation of nodes in any of the
ZooKeeper create modes.</li><li>Get and Set the data contents of arbitrary
cluster nodes.</li><li>Create and retrieve the list the child nodes attached to
a particular node.</li><li>A Distributed <a shape="rect"
href="routepolicy.html">RoutePolicy</a> that leverages a Leader election
coordinated by ZooKeeper to determine if exchanges should get
processed.</li></ol><p>Maven users will need to add the following dependency to
their <code>pom.xml</code> for this component:</p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: xml; gutter: false"
type="syntaxhighlighter"><![CDATA[<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-zookeeper</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>
]]></script>
-</div></div>
-
-<h3 id="Zookeeper-URIformat">URI format</h3>
-
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-zookeeper://zookeeper-server[:port][/path][?options]
+</div></div><h3 id="Zookeeper-URIformat">URI format</h3><div class="code panel
pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[zookeeper://zookeeper-server[:port][/path][?options]
]]></script>
-</div></div>
-
-<p>The path from the uri specifies the node in the ZooKeeper server (aka
znode) that will be the target of the endpoint.</p>
-
-<h3 id="Zookeeper-Options">Options</h3>
-<div class="confluenceTableSmall">
-<table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1"
class="confluenceTh"><p> Name </p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p> Default Value </p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p> Description </p></th></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>path</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> The node in the ZooKeeper server (aka znode)
</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>
<code>listChildren</code> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>false</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> Whether the children of the node should be
listed </p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>
<code>repeat</code> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>false</code> </p></td><td colspan="
1" rowspan="1" class="confluenceTd"><p> Should changes to the znode be
'watched' and repeatedly processed. </p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>backoff</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> <code>5000</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> The time interval to backoff
for after an error before retrying. </p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>timeout</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> <code>5000</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> The time interval to wait on
connection before timing out. </p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>create</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>false</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> Should the endpoint create the
node if it does not currently exi
st. </p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>
<code>createMode</code> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>EPHEMERAL</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> The create mode that should be used for
the newly created node (see below). </p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>listChildren</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> <code>false</code>
</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> Whether to
recursive get children of the zknode as well. </p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>sendEmptyMessageOnDelete</code>
</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> <code>true</code>
</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> <strong>Camel
2.10:</strong> Upon the delete of a znode, should an empty message be send to
the consumer </p></td></tr></tbody>
</table>
-</div>
-
-<h3 id="Zookeeper-Usecases">Use cases</h3>
-
-<h4 id="Zookeeper-Readingfromaznode.">Reading from a znode.</h4>
-
-<p>The following snippet will read the data from the znode
'/somepath/somenode/' provided that it already exists. The data retrieved
will<br clear="none">
-be placed into an exchange and passed onto the rest of the route.</p>
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-from("zookeeper://localhost:39913/somepath/somenode").to("mock:result");
+</div></div><p>The path from the uri specifies the node in the ZooKeeper
server (aka znode) that will be the target of the endpoint.</p><h3
id="Zookeeper-Options">Options</h3><div class="confluenceTableSmall">
+<table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1"
class="confluenceTh"><p> Name </p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p> Default Value </p></th><th colspan="1" rowspan="1"
class="confluenceTh"><p> Description </p></th></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>path</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> The node in the ZooKeeper server (aka znode)
</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>
<code>listChildren</code> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>false</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> Whether the children of the node should be
listed </p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>
<code>repeat</code> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>false</code> </p></td><td colspan="
1" rowspan="1" class="confluenceTd"><p> Should changes to the znode be
'watched' and repeatedly processed. </p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>backoff</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> <code>5000</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> The time interval to backoff
for after an error before retrying. </p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>timeout</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> <code>5000</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> The time interval to wait on
connection before timing out. </p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>create</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>false</code> </p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p> Should the endpoint create the
node if it does not currently exi
st. </p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>
<code>createMode</code> </p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p> <code>EPHEMERAL</code> </p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> The create mode that should be used for
the newly created node (see below). </p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p> <code>sendEmptyMessageOnDelete</code>
</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> <code>true</code>
</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> <strong>Camel
2.10:</strong> Upon the delete of a znode, should an empty message be send to
the consumer </p></td></tr></tbody></table>
+</div><h3 id="Zookeeper-Usecases">Use cases</h3><h4
id="Zookeeper-Readingfromaznode.">Reading from a znode.</h4><p>The following
snippet will read the data from the znode '/somepath/somenode/' provided that
it already exists. The data retrieved will<br clear="none"> be placed into an
exchange and passed onto the rest of the route.</p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[from("zookeeper://localhost:39913/somepath/somenode").to("mock:result");
]]></script>
-</div></div>
-
-<p>if the node does not yet exist then a flag can be supplied to have the
endpoint await its creation</p>
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-from("zookeeper://localhost:39913/somepath/somenode?awaitCreation=true").to("mock:result");
+</div></div><p>if the node does not yet exist then a flag can be supplied to
have the endpoint await its creation</p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[from("zookeeper://localhost:39913/somepath/somenode?awaitCreation=true").to("mock:result");
]]></script>
-</div></div>
-
-<h4 id="Zookeeper-Readingfromaznode-(additionalCamel2.10onwards)">Reading from
a znode - (additional Camel 2.10 onwards)</h4>
-
-<p>When data is read due to a WatchedEvent received from the ZooKeeper
ensemble, the CamelZookeeperEventType header holds ZooKeeper's <a shape="rect"
class="external-link"
href="http://zookeeper.apache.org/doc/current/api/org/apache/zookeeper/Watcher.Event.EventType.html";>EventType</a>
value from that WatchedEvent. If the data is read initially (not triggered by
a WatchedEvent) the CamelZookeeperEventType header will not be set.</p>
-
-
-<h4 id="Zookeeper-Writingtoaznode.">Writing to a znode.</h4>
-
-<p>The following snippet will write the payload of the exchange into the znode
at '/somepath/somenode/' provided that it already exists</p>
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-from("direct:write-to-znode").to("zookeeper://localhost:39913/somepath/somenode");
+</div></div><h4
id="Zookeeper-Readingfromaznode-(additionalCamel2.10onwards)">Reading from a
znode - (additional Camel 2.10 onwards)</h4><p>When data is read due to a
WatchedEvent received from the ZooKeeper ensemble, the CamelZookeeperEventType
header holds ZooKeeper's <a shape="rect" class="external-link"
href="http://zookeeper.apache.org/doc/current/api/org/apache/zookeeper/Watcher.Event.EventType.html";>EventType</a>
value from that WatchedEvent. If the data is read initially (not triggered by
a WatchedEvent) the CamelZookeeperEventType header will not be set.</p><h4
id="Zookeeper-Writingtoaznode.">Writing to a znode.</h4><p>The following
snippet will write the payload of the exchange into the znode at
'/somepath/somenode/' provided that it already exists</p><div class="code panel
pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[from("direct:write-to-znode").to("zookeeper://localhost:39913/somepath/somenode");
]]></script>
-</div></div>
-
-<p>For flexibility, the endpoint allows the target znode to be specified
dynamically as a message header. If a header keyed by the string
'CamelZooKeeperNode' is present then the value of the header will be used as
the path to the znode on the server. For instance using the same route
definition above, the following code snippet will write the data not to
'/somepath/somenode' but to the path from the header
'/somepath/someothernode'</p>
-
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-Exchange e = createExchangeWithBody(testPayload);
+</div></div><p>For flexibility, the endpoint allows the target znode to be
specified dynamically as a message header. If a header keyed by the string
'CamelZooKeeperNode' is present then the value of the header will be used as
the path to the znode on the server. For instance using the same route
definition above, the following code snippet will write the data not to
'/somepath/somenode' but to the path from the header
'/somepath/someothernode'</p><div class="code panel pdl" style="border-width:
1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[Exchange e =
createExchangeWithBody(testPayload);
template.sendBodyAndHeader("direct:write-to-znode", e,
"CamelZooKeeperNode", "/somepath/someothernode");
]]></script>
-</div></div>
-
-<p>To also create the node if it does not exist the 'create' option should be
used.</p>
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-from("direct:create-and-write-to-znode").to("zookeeper://localhost:39913/somepath/somenode?create=true");
+</div></div><p>To also create the node if it does not exist the 'create'
option should be used.</p><div class="code panel pdl" style="border-width:
1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[from("direct:create-and-write-to-znode").to("zookeeper://localhost:39913/somepath/somenode?create=true");
]]></script>
-</div></div>
-
-<p>Starting <strong>version 2.11</strong> it is also possible to
<strong>delete</strong> a node using the header 'CamelZookeeperOperation' by
setting it to 'DELETE'.</p>
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-from("direct:delete-znode").setHeader(ZooKeeperMessage.ZOOKEEPER_OPERATION,
constant("DELETE")).to("zookeeper://localhost:39913/somepath/somenode");
+</div></div><p>Starting <strong>version 2.11</strong> it is also possible to
<strong>delete</strong> a node using the header 'CamelZookeeperOperation' by
setting it to 'DELETE'.</p><div class="code panel pdl" style="border-width:
1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[from("direct:delete-znode").setHeader(ZooKeeperMessage.ZOOKEEPER_OPERATION,
constant("DELETE")).to("zookeeper://localhost:39913/somepath/somenode");
]]></script>
-</div></div>
-
-<p>or equivalently</p>
-
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: xml; gutter: false"
type="syntaxhighlighter"><![CDATA[
-<route>
+</div></div><p>or equivalently</p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: xml; gutter: false"
type="syntaxhighlighter"><![CDATA[<route>
<from uri="direct:delete-znode" />
<setHeader headerName="CamelZookeeperOperation">
<constant>DELETE</constant>
@@ -190,45 +127,18 @@ from("direct:delete-znode").se
<to uri="zookeeper://localhost:39913/somepath/somenode" />
</route>
]]></script>
-</div></div>
-
-<p>ZooKeeper nodes can have different types; they can be 'Ephemeral' or
'Persistent' and 'Sequenced' or 'Unsequenced'. For further information of each
type you can check <a shape="rect" class="external-link"
href="http://zookeeper.apache.org/doc/trunk/zookeeperProgrammers.html#Ephemeral+Nodes";>here</a>.
By default endpoints will create unsequenced, ephemeral nodes, but the type
can be easily manipulated via a uri config parameter or via a special message
header. The values expected for the create mode are simply the names from the
CreateMode enumeration</p>
-
-<ul
class="alternate"><li>PERSISTENT</li><li>PERSISTENT_SEQUENTIAL</li><li>EPHEMERAL</li><li>EPHEMERAL_SEQUENTIAL</li></ul>
-
-
-<p>For example to create a persistent znode via the URI config</p>
-
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-from("direct:create-and-write-to-persistent-znode").to("zookeeper://localhost:39913/somepath/somenode?create=true&createMode=PERSISTENT");
+</div></div><p>ZooKeeper nodes can have different types; they can be
'Ephemeral' or 'Persistent' and 'Sequenced' or 'Unsequenced'. For further
information of each type you can check <a shape="rect" class="external-link"
href="http://zookeeper.apache.org/doc/trunk/zookeeperProgrammers.html#Ephemeral+Nodes";>here</a>.
By default endpoints will create unsequenced, ephemeral nodes, but the type
can be easily manipulated via a uri config parameter or via a special message
header. The values expected for the create mode are simply the names from the
CreateMode enumeration</p><ul
class="alternate"><li>PERSISTENT</li><li>PERSISTENT_SEQUENTIAL</li><li>EPHEMERAL</li><li>EPHEMERAL_SEQUENTIAL</li></ul><p>For
example to create a persistent znode via the URI config</p><div class="code
panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[from("direct:create-and-write-to-persistent-znode").to("zookeeper://localhost:39913/somepath/somenode?create=true&createMode=PERSISTENT");
]]></script>
-</div></div>
-
-<p>or using the header 'CamelZookeeperCreateMode'</p>
-
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-Exchange e = createExchangeWithBody(testPayload);
+</div></div><p>or using the header 'CamelZookeeperCreateMode'</p><div
class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[Exchange e =
createExchangeWithBody(testPayload);
template.sendBodyAndHeader("direct:create-and-write-to-persistent-znode",
e, "CamelZooKeeperCreateMode", "PERSISTENT");
]]></script>
-</div></div>
-
-
-<h3 id="Zookeeper-ZooKeeperenabledRoutepolicy.">ZooKeeper enabled Route
policy.</h3>
-
-<p>ZooKeeper allows for very simple and effective leader election out of the
box; This component exploits this election capability in a <a shape="rect"
href="routepolicy.html">RoutePolicy</a> to control when and how routes are
enabled. This policy would typically be used in fail-over scenarios, to control
identical instances of a route across a cluster of Camel based servers. A very
common scenario is a simple 'Master-Slave' setup where there are multiple
instances of a route distributed across a cluster but only one of them, that of
the master, should be running at a time. If the master fails, a new master
should be elected from the available slaves and the route in this new master
should be started.</p>
-
-<p>The policy uses a common znode path across all instances of the RoutePolicy
that will be involved in the election. Each policy writes its id into this node
and zookeeper will order the writes in the order it received them. The policy
then reads the listing of the node to see what postion of its id; this postion
is used to determine if the route should be started or not. The policy is
configured at startup with the number of route instances that should be started
across the cluster and if its position in the list is less than this value then
its route will be started. For a Master-slave scenario, the route is configured
with 1 route instance and only the first entry in the listing will start its
route. All policies watch for updates to the listing and if the listing changes
they recalculate if their route should be started. For more info on Zookeeper's
Leader election capability see <a shape="rect" class="external-link"
href="http://zookeeper.apache.org/doc/trunk/recipes.html#sc_l
eaderElection">this page</a>.</p>
-
-<p>The following example uses the node '/someapplication/somepolicy' for the
election and is set up to start only the top '1' entries in the node listing
i.e. elect a master</p>
-<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
-<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[
-ZooKeeperRoutePolicy policy = new
ZooKeeperRoutePolicy("zookeeper:localhost:39913/someapp/somepolicy",
1);
+</div></div><h3 id="Zookeeper-ZooKeeperenabledRoutepolicy.">ZooKeeper enabled
Route policy.</h3><p>ZooKeeper allows for very simple and effective leader
election out of the box; This component exploits this election capability in a
<a shape="rect" href="routepolicy.html">RoutePolicy</a> to control when and how
routes are enabled. This policy would typically be used in fail-over scenarios,
to control identical instances of a route across a cluster of Camel based
servers. A very common scenario is a simple 'Master-Slave' setup where there
are multiple instances of a route distributed across a cluster but only one of
them, that of the master, should be running at a time. If the master fails, a
new master should be elected from the available slaves and the route in this
new master should be started.</p><p>The policy uses a common znode path across
all instances of the RoutePolicy that will be involved in the election. Each
policy writes its id into this node and zookeeper will order the
writes in the order it received them. The policy then reads the listing of
the node to see what postion of its id; this postion is used to determine if
the route should be started or not. The policy is configured at startup with
the number of route instances that should be started across the cluster and if
its position in the list is less than this value then its route will be
started. For a Master-slave scenario, the route is configured with 1 route
instance and only the first entry in the listing will start its route. All
policies watch for updates to the listing and if the listing changes they
recalculate if their route should be started. For more info on Zookeeper's
Leader election capability see <a shape="rect" class="external-link"
href="http://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection";>this
page</a>.</p><p>The following example uses the node
'/someapplication/somepolicy' for the election and is set up to start only the
top '1' entries in the node listing
i.e. elect a master</p><div class="code panel pdl" style="border-width:
1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false"
type="syntaxhighlighter"><![CDATA[ZooKeeperRoutePolicy policy = new
ZooKeeperRoutePolicy("zookeeper:localhost:39913/someapp/somepolicy",
1);
from("direct:policy-controlled").routePolicy(policy).to("mock:controlled");
]]></script>
-</div></div>
-<h3 id="Zookeeper-SeeAlso">See Also</h3>
+</div></div><p></p><h3 id="Zookeeper-SeeAlso">See Also</h3>
<ul><li><a shape="rect" href="configuring-camel.html">Configuring
Camel</a></li><li><a shape="rect"
href="component.html">Component</a></li><li><a shape="rect"
href="endpoint.html">Endpoint</a></li><li><a shape="rect"
href="getting-started.html">Getting Started</a></li></ul></div>
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