Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved


Chapter 24 Cache OM and Cluster Configuration : Configuring the TIBCO BusinessEvents DataGrid Discover URL

Configuring the TIBCO BusinessEvents DataGrid Discover URL
When a cluster starts up, and also when new members join a cluster, a discovery process enables the members to discover each other. The discover URL specifies how an engine (node) listens for discovery requests from nodes attempting to join the cluster.
After the discovery is complete, the members communicate internally using a listen URL (explained in Configuring the TIBCO BusinessEvents DataGrid Listen URL).
Two types of discovery are available:
Configuration for both discovery methods is explained below.
If No Other Cluster Members are Started
If a newly started node does not discover any running cluster nodes, the behavior is different depending on the type of discovery used:
Multicast (PGM) Cluster Member Discovery
The discover URL for multicast discovery uses PGM (Pragmatic General Multicast) protocol.
The discovery property is be.engine.cluster.as.discover.url. For multicast discovery, the value is a URL with the following format:
tibpgm://destinationPort/network/
The default values equate to the following: //7888/;239.8.8.9/
Specify the parameters as follows.
The format is as follows: interface;multicast group address
The value for interface is unique to a node. It must also be the same in both the discovery and the listen URLs for a node. If there are multiple interfaces on one machine, specify the interface you want to use and do not rely on the default value.
The value for multicast group address must be the same on all machines in the cluster.
The default value for interface is the first available interface provided by the operating system hosts file for the machine.
Note  If the desired interface is not listed in the hosts file then PGM picks the first available interface in the file. (On most operating systems, this file is called the /etc/hosts file.) If the first interface is the loopback interface (127.0.0.1) then PGM fails to start. In this case you would see a stacktrace exception in the log file such as the following:
The default value for multicast group address is the multicast group address 239.8.8.9.
Unicast (Well-Known Address) Cluster Member Discovery
If you cannot or do not wish to use multicast discovery in your environment, then configure unicast discovery, also known as "well-known address" or WKA discovery. These "well-known addresses" enable a newly started node to discover existing membersUnicast discovery uses the TCP protocol.
The discovery property is be.engine.cluster.as.discover.url. For unicast discovery, the value is a semicolon-separated list comprising a sub-set of all the listen URLs (which are different for each PU), using this format:
tcp://ip:port[;ip:port]*/
One cluster node in the WKA list must be running at all times  At least one cluster node specified in the well-known address list must be running at all times, so that other new members can join the cluster (metaspace). If all nodes specified in the well-known address list stop, then other nodes that are still running continue to function, but they print warnings to the console and no new members can connect to this cluster.
For WKA discovery, make discover URL a cluster-level property and listen URL a PU-level property  The discover URL property (be.engine.cluster.as.discover.url) must be present and configured identically for all potential cluster members. Therefore add this property at the cluster level of the CDD file. The listen URL property (be.engine.cluster.as.listen.url) must be present and configured differently for each possible cluster member. Therefore add this property at the PU level.

Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved