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| |
| <document> |
| <properties> |
| <title>Lateral UDP Discovery</title> |
| <author email="asmuts@apache.org">Aaron Smuts</author> |
| </properties> |
| |
| <body> |
| <section name="Lateral UDP Discovery"> |
| <p> |
| Rather than list all the other lateral servers in the configuration |
| file, you can configure the TCP lateral to use UDP |
| discovery. In discovery mode, lateral TCP caches will broadcast |
| to a multicast address and port, letting all listeners know where they are. |
| </p> |
| <p> |
| On startup each lateral will issue a special message requesting a |
| broadcast from the other caches. Normal broadcasts occur every |
| 15 seconds. (This is to be made configurable.) Regions that don't |
| receive, are running in send only mode, don't broadcast anything but requests. |
| </p> |
| <p> |
| The normal broadcasts publish the address and port of the service. |
| This can be configured as <code>TcpListenerHost</code> and |
| <code>TcpListenerPort</code>, respectively. If the service address |
| is not set, the service tries to detect a suitable address using the |
| same interface as the one that is used for multicast. If the multicast |
| uses IPv6, a link-local IPv6 address is selected if one exists. |
| Otherwise, a site-local IPv4 address is chosen. If that attempt also |
| fails, the first address on any non-loopback interface is used. |
| </p> |
| <p> |
| When a lateral receives a discovery message it will try to add |
| the lateral to the nowait facade for the region. If it already exists |
| nothing happens. If a region is not configured to send laterally, nothing |
| happens, since it doesn't have a no wait. |
| </p> |
| <p> |
| This allows you to have the same configuration on every machine. |
| </p> |
| <subsection name="Configuration"> |
| <p> |
| The configuration is fairly straightforward and is done in the |
| auxiliary cache section of the <code>cache.ccf</code> |
| configuration file. In the example below, a TCP |
| Lateral Auxiliary Cache referenced by <code>LTCP</code> is created. It uses |
| UDP Discovery to locate other servers. It broadcasts to |
| multicast address <code>228.5.6.8</code> and port <code>6780</code>. |
| It listens to port <code>1110</code>. The UDP datagram time-to-live |
| is 4 hops. |
| </p> |
| <source><![CDATA[ |
| jcs.auxiliary.LTCP=org.apache.commons.jcs3.auxiliary.lateral.socket.tcp.LateralTCPCacheFactory |
| jcs.auxiliary.LTCP.attributes=org.apache.commons.jcs3.auxiliary.lateral.socket.tcp.TCPLateralCacheAttributes |
| jcs.auxiliary.LTCP.attributes.TcpListenerPort=1110 |
| jcs.auxiliary.LTCP.attributes.PutOnlyMode=true |
| jcs.auxiliary.LTCP.attributes.UdpDiscoveryAddr=228.5.6.8 |
| jcs.auxiliary.LTCP.attributes.UdpDiscoveryPort=6780 |
| jcs.auxiliary.LTCP.attributes.UdpDiscoveryEnabled=true |
| jcs.auxiliary.LTCP.attributes.UdpTTL=4 |
| ]]></source> |
| </subsection> |
| <subsection name="Multi-homed hosts"> |
| <p> |
| On machines that have several network interfaces, it might be |
| desirable to fix the interface that is used for multicast. |
| For this purpose, the network interface can be specified in the |
| configuration (see below). |
| </p> |
| <p> |
| If the network interface is not specified, JCS tries to detect a |
| suitable interface. The selected interface is logged on INFO level. |
| Search for the message "Using network interface" in your log file. |
| </p> |
| <source><![CDATA[ |
| jcs.auxiliary.LTCP=org.apache.commons.jcs3.auxiliary.lateral.socket.tcp.LateralTCPCacheFactory |
| jcs.auxiliary.LTCP.attributes=org.apache.commons.jcs3.auxiliary.lateral.socket.tcp.TCPLateralCacheAttributes |
| jcs.auxiliary.LTCP.attributes.TcpListenerPort=1110 |
| jcs.auxiliary.LTCP.attributes.PutOnlyMode=true |
| jcs.auxiliary.LTCP.attributes.UdpDiscoveryInterface=en0 |
| jcs.auxiliary.LTCP.attributes.UdpDiscoveryAddr=228.5.6.8 |
| jcs.auxiliary.LTCP.attributes.UdpDiscoveryPort=6780 |
| jcs.auxiliary.LTCP.attributes.UdpDiscoveryEnabled=true |
| jcs.auxiliary.LTCP.attributes.UdpTTL=4 |
| ]]></source> |
| </subsection> |
| </section> |
| </body> |
| </document> |
