| 1 | <html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Apache Tomcat Configuration Reference - The Cluster Membership object</title><meta value="Filip Hanik" name="author"><meta value="fhanik@apache.org" name="email"></head><body vlink="#525D76" alink="#525D76" link="#525D76" text="#000000" bgcolor="#ffffff"><table cellspacing="0" width="100%" border="0"><!--PAGE HEADER--><tr><td><!--PROJECT LOGO--><a href="http://tomcat.apache.org/"><img border="0" alt=" |
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| 2 | The Apache Tomcat Servlet/JSP Container |
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| 3 | " align="right" src="../../images/tomcat.gif"></a></td><td><font face="arial,helvetica,sanserif"><h1>Apache Tomcat 6.0</h1></font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img border="0" alt="Apache Logo" align="right" src="../../images/asf-logo.gif"></a></td></tr></table><table cellspacing="4" width="100%" border="0"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr size="1" noshade></td></tr><tr><!--RIGHT SIDE MAIN BODY--><td align="left" valign="top" width="80%"><table cellspacing="4" width="100%" border="0"><tr><td valign="top" align="left"><h1>Apache Tomcat Configuration Reference</h1><h2>The Cluster Membership object</h2></td><td nowrap="true" valign="top" align="right"><img border="0" hspace="0" vspace="0" height="1" width="1" src="../../images/void.gif"></td></tr></table><table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#525D76"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Introduction"><strong>Introduction</strong></a></font></td></tr><tr><td><blockquote> |
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| 4 | <p> |
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| 5 | The membership component in the Apache Tribes <a href="cluster-channel.html">Channel</a> is responsible |
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| 6 | for dynamic discovery of other members(nodes) in the cluster. |
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| 7 | </p> |
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| 8 | </blockquote></td></tr></table><table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#525D76"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Default Implementation"><strong>Default Implementation</strong></a></font></td></tr><tr><td><blockquote> |
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| 9 | <p> |
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| 10 | The default implementation of the cluster group notification is built on top of multicast heartbeats |
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| 11 | sent using UDP packets to a multicast IP address. |
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| 12 | Cluster members are grouped together by using the same multicast address/port combination. |
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| 13 | Each member sends out a heartbeat with a given interval (<code>frequency</code>), and this |
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| 14 | heartbeat is used for dynamic discovery. |
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| 15 | In a similar fashion, if a heartbeat has not been received in a timeframe specified by <code>dropTime</code> |
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| 16 | ms. a member is considered suspect and the channel and any membership listener will be notified. |
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| 17 | </p> |
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| 18 | </blockquote></td></tr></table><table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#525D76"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Attributes"><strong>Attributes</strong></a></font></td></tr><tr><td><blockquote> |
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| 19 | |
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| 20 | <table cellpadding="2" cellspacing="0" border="0"><tr><td bgcolor="#828DA6"><font face="arial,helvetica.sanserif" color="#ffffff"><a name="Multicast Attributes"><strong>Multicast Attributes</strong></a></font></td></tr><tr><td><blockquote> |
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| 21 | |
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| 22 | <table cellpadding="5" border="1"><tr><th bgcolor="#023264" width="15%"><font color="#ffffff">Attribute</font></th><th bgcolor="#023264" width="85%"><font color="#ffffff">Description</font></th></tr><tr><td valign="center" align="left"><strong><code>className</code></strong></td><td valign="center" align="left"> |
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| 23 | <p> |
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| 24 | The default value is <code>org.apache.catalina.tribes.membership.McastService</code> |
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| 25 | and is currently the only implementation. |
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| 26 | This implementation uses multicast heartbeats for member discovery. |
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| 27 | </p> |
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| 28 | </td></tr><tr><td valign="center" align="left"><code>address</code></td><td valign="center" align="left"> |
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| 29 | <p> |
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| 30 | The multicast address that the membership will broadcast its presence and listen |
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| 31 | for other heartbeats on. The default value is <code>228.0.0.4</code> |
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| 32 | Make sure your network is enabled for multicast traffic.<br> |
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| 33 | The multicast address, in conjunction with the <code>port</code> is what |
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| 34 | creates a cluster group. To divide up your farm into several different group, or to |
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| 35 | split up QA from production, change the <code>port</code> or the <code>address</code> |
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| 36 | <br>Previously known as mcastAddr. |
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| 37 | </p> |
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| 38 | </td></tr><tr><td valign="center" align="left"><code>port</code></td><td valign="center" align="left"> |
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| 39 | <p> |
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| 40 | The multicast port, the default value is <code>45564</code><br> |
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| 41 | The multicast port, in conjunction with the <code>address</code> is what |
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| 42 | creates a cluster group. To divide up your farm into several different group, or to |
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| 43 | split up QA from production, change the <code>port</code> or the <code>address</code> |
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| 44 | </p> |
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| 45 | </td></tr><tr><td valign="center" align="left"><code>frequency</code></td><td valign="center" align="left"> |
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| 46 | <p> |
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| 47 | The frequency in milliseconds in which heartbeats are sent out. The default value is <code>500</code> ms.<br> |
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| 48 | In most cases the default value is sufficient. Changing this value, simply changes the interval in between heartbeats. |
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| 49 | </p> |
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| 50 | </td></tr><tr><td valign="center" align="left"><code>dropTime</code></td><td valign="center" align="left"> |
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| 51 | <p> |
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| 52 | The membership component will time out members and notify the Channel if a member fails to send a heartbeat within |
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| 53 | a give time. The default value is <code>3000</code> ms. This means, that if a heartbeat is not received from a |
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| 54 | member in that timeframe, the membership component will notify the cluster of this.<br> |
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| 55 | On a high latency network you may wish to increase this value, to protect against false positives.<br> |
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| 56 | Apache Tribes also provides a <a href="cluster-interceptor.html#tcpfailuredetector"><code>TcpFailureDetector</code></a> that will |
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| 57 | verify a timeout using a TCP connection when a heartbeat timeout has occurred. This protects against false positives. |
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| 58 | </p> |
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| 59 | </td></tr><tr><td valign="center" align="left"><code>bind</code></td><td valign="center" align="left"> |
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| 60 | <p> |
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| 61 | Use this attribute if you wish to bind your multicast traffic to a specific network interface. |
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| 62 | By default, or when this attribute is unset, it tries to bind to <code>0.0.0.0</code> and sometimes on multihomed hosts |
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| 63 | this becomes a problem. |
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| 64 | </p> |
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| 65 | </td></tr><tr><td valign="center" align="left"><code>ttl</code></td><td valign="center" align="left"> |
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| 66 | <p> |
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| 67 | The time-to-live setting for the multicast heartbeats. |
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| 68 | This setting should be a value between 0 and 255. The default value is VM implementation specific. |
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| 69 | </p> |
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| 70 | </td></tr><tr><td valign="center" align="left"><code>domain</code></td><td valign="center" align="left"> |
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| 71 | <p> |
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| 72 | Apache Tribes has the ability to logically group members into domains, by using this domain attribute. |
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| 73 | The <code>org.apache.catalina.tribes.Member.getDomain()</code> method returns the value specified here. |
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| 74 | </p> |
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| 75 | </td></tr><tr><td valign="center" align="left"><code>soTimeout</code></td><td valign="center" align="left"> |
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| 76 | <p> |
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| 77 | The sending and receiving of heartbeats is done on a single thread, hence to avoid blocking this thread forever, |
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| 78 | you can control the <code>SO_TIMEOUT</code> value on this socket.<br> |
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| 79 | If a value smaller or equal to 0 is presented, the code will default this value to frequency |
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| 80 | </p> |
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| 81 | </td></tr></table> |
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| 82 | |
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| 83 | |
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| 84 | </blockquote></td></tr></table> |
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| 85 | |
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| 86 | |
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| 87 | </blockquote></td></tr></table></td></tr><!--FOOTER SEPARATOR--><tr><td colspan="2"><hr size="1" noshade></td></tr><!--PAGE FOOTER--><tr><td colspan="2"><div align="center"><font size="-1" color="#525D76"><em> |
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| 88 | Copyright © 1999-2008, Apache Software Foundation |
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| 89 | </em></font></div></td></tr></table></body></html> |
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