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<?xml version="1.0" encoding="UTF-8"?>
<!--
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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limitations under the License.
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<!DOCTYPE document [
<!ENTITY project SYSTEM "project.xml">
]>
<document url="cluster-interceptor.html">
&project;
<properties>
<author email="fhanik@apache.org">Filip Hanik</author>
<title>The Channel Interceptor object</title>
</properties>
<body>
<section name="Table of Contents">
<toc/>
</section>
<section name="Introduction">
<p>
Apache Tribes supports an interceptor architecture to intercept both messages and membership notifications.
This architecture allows decoupling of logic and opens the way for some very kewl feature add ons.
</p>
</section>
<section name="Available Interceptors">
<ul>
<li><code>org.apache.catalina.tribes.group.interceptors.TcpFailureDetector</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.NonBlockingCoordinator</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.OrderInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.SimpleCoordinator</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.StaticMembershipInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.TwoPhaseCommitInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.DomainFilterInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.FragmentationInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.GzipInterceptor</code></li>
<li><code>org.apache.catalina.tribes.group.interceptors.TcpPingInterceptor</code></li>
</ul>
</section>
<section name="Static Membership">
<p>
In addition to dynamic discovery, Apache Tribes also supports static membership, with membership verification.
To achieve this add the <code>org.apache.catalina.tribes.group.interceptors.StaticMembershipInterceptor</code>
underneath the <code>org.apache.catalina.tribes.group.interceptors.TcpFailureDetector</code> interceptor.
Inside the <code>StaticMembershipInterceptor</code> you can add the static members you wish to have.
The <code>TcpFailureDetector</code> will do a health check on the static members,and also monitor them for crashes
so they will have the same level of notification mechanism as the members that are automatically discovered.</p>
<source><![CDATA[ <Interceptor className="org.apache.catalina.tribes.group.interceptors.StaticMembershipInterceptor">
<Member className="org.apache.catalina.tribes.membership.StaticMember"
port="5678"
securePort="-1"
host="tomcat01.mydomain.com"
domain="staging-cluster"
uniqueId="{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}"/>
</Interceptor>]]></source>
</section>
<section name="Attributes">
<subsection name="Common Attributes">
<attributes>
<attribute name="className" required="true">
Required, as there is no default
</attribute>
<attribute name="optionFlag" required="false">
If you want the interceptor to trigger on certain message depending on the message's option flag,
you can setup the interceptors flag here.
The default value is <code>0</code>, meaning this interceptor will trigger on all messages.
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.tribes.group.interceptors.DomainFilterInterceptor Attributes">
<attributes>
<attribute name="domain" required="true">
The logical cluster domain that this Interceptor accepts.
Two different type of values are possible:<br/>
1. Regular string values like "staging-domain" or "tomcat-cluster" will be converted into bytes
using ISO-8859-1 encoding.<br/>
2. byte array in string form, for example {216,123,12,3}<br/>
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor Attributes">
<attributes>
<attribute name="className" required="true">
Required, This dispatcher uses JDK 1.5 java.util.concurrent package
</attribute>
<attribute name="optionFlag" required="false">
The default and hard coded value is <code>8 (org.apache.catalina.tribes.Channel.SEND_OPTIONS_ASYNCHRONOUS)</code>.
The dispatcher will trigger on this value only, as it is predefined by Tribes.
The other attributes are inherited from its base class <code>org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor</code>.
</attribute>
<attribute name="maxThreads" required="false">
The maximum number of threads in this pool, default is 10.
</attribute>
<attribute name="maxSpareThreads" required="false">
The number of threads to keep in the pool, default is 2.
</attribute>
<attribute name="keepAliveTime" required="false">
Maximum number of milliseconds of until Idle thread terminates. Default value is 5000(5 seconds).
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor Attributes">
<attributes>
<attribute name="className" required="true">
Required, Same implementation as <code>MessageDispatch15Interceptor</code>, but with JDK 1.4 compliance.
</attribute>
<attribute name="optionFlag" required="false">
The default and hard coded value is <code>8 (org.apache.catalina.tribes.Channel.SEND_OPTIONS_ASYNCHRONOUS)</code>.
The dispatcher will trigger on this value only, as it is predefined by Tribes.
</attribute>
<attribute name="alwaysSend" required="false">
What behavior should be executed when the dispatch queue is full. If <code>true</code> (default), then the message is
is sent synchronously, if <code>false</code> an error is thrown.
</attribute>
<attribute name="maxQueueSize" required="false">
Size in bytes of the dispatch queue, the default value is <code> 1024*1024*64 (64MB)</code> sets the maximum queue size for the dispatch queue
if the queue fills up, one can trigger the behavior, if <code>alwaysSend</code> is set to true, the message will be sent synchronously
if the flag is false, an error is thrown
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector Attributes">
<attributes>
<attribute name="connectTimeout" required="false">
Specifies the timeout, in milliseconds, to use when attempting a TCP connection
to the suspect node. Default is 1000.
</attribute>
<attribute name="performSendTest" required="false">
If true is set, send a test message to the suspect node. Default is true.
</attribute>
<attribute name="performReadTest" required="false">
If true is set, read the response of the test message that sent. Default is false.
<strong>Note: </strong>if <code>performSendTest</code> is false, this attribute will have no effect.
</attribute>
<attribute name="readTestTimeout" required="false">
Specifies the timeout, in milliseconds, to use when performing a read test
to the suspicious node. Default is 5000.
</attribute>
<attribute name="removeSuspectsTimeout" required="false">
The maximum time(in seconds) for remove from removeSuspects. Member of
removeSuspects will be automatically removed after removeSuspectsTimeout.
If a negative value specified, the removeSuspects members never be
removed until disappeared really. If the attribute is not provided,
a default of 300 seconds (5 minutes) is used.
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.tribes.group.interceptors.TcpPingInterceptor Attributes">
<attributes>
<attribute name="interval" required="false">
If useThread == true, defines the interval of sending a ping message.
default is 1000 ms.
</attribute>
<attribute name="useThread" required="false">
Flag of whether to start a thread for sending a ping message.
If set to true, this interceptor will start a local thread for sending a ping message.
if set to false, channel heartbeat will send a ping message.
default is false.
</attribute>
</attributes>
</subsection>
<subsection name="org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor Attributes">
<attributes>
<attribute name="interval" required="false">
Defines the interval in number of messages when we are to report the throughput statistics.
The report is logged to the <code>org.apache.juli.logging.LogFactory.getLog(ThroughputInterceptor.class)</code>
logger under the <code>INFO</code> level.
Default value is to report every <code>10000</code> messages.
</attribute>
</attributes>
</subsection>
<subsection name="Nested element StaticMember Attributes">
<attributes>
<attribute name="className" required="true">
Only one implementation available:<code>org.apache.catalina.tribes.membership.StaticMember</code>
</attribute>
<attribute name="port" required="true">
The port that this static member listens to for cluster messages
</attribute>
<attribute name="securePort" required="false">
The secure port this static member listens to for encrypted cluster messages
default value is <code>-1</code>, this value means the member is not listening on a secure port
</attribute>
<attribute name="host" required="true">
The host (or network interface) that this static member listens for cluster messages.
Three different type of values are possible:<br/>
1. IP address in the form of "216.123.1.23"<br/>
2. Hostnames like "tomcat01.mydomain.com" or "tomcat01" as long as they resolve correctly<br/>
3. byte array in string form, for example {216,123,12,3}<br/>
</attribute>
<attribute name="domain" required="true">
The logical cluster domain for this this static member listens for cluster messages.
Two different type of values are possible:<br/>
1. Regular string values like "staging-domain" or "tomcat-cluster" will be converted into bytes
using ISO-8859-1 encoding.
2. byte array in string form, for example {216,123,12,3}<br/>
</attribute>
<attribute name="uniqueId" required="true">
A universally uniqueId for this static member.
The values must be 16 bytes in the following form:<br/>
1. byte array in string form, for example {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}<br/>
</attribute>
</attributes>
</subsection>
<!--TODO Document all the interceptors-->
</section>
</body>
</document>
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