Learn how to improve resilience and reliability of the OpenText AppWorks Gateway by deploying the Gateway in a cluster.
You can deploy and configure additional AppWorks Gateway servers to use an existing AppWorks Gateway database. Any application, service, or component that is installed on one node in the cluster is automatically installed on all of the other nodes. All settings changes are also propagated to all of the nodes. You do not need to perform any manual steps on any other node or restart the Apache Tomcat service. However, you must restart the Apache Tomcat service if you change any of the following settings in the AppWorks Gateway:
On the Notifications page, changes to the Back-channel Stale Connection Cleanup Period (s) will only take effect when the current period elapses or when the Apache Tomcat servers are restarted.
On the General Settings page, changes to the Session Token Cleanup Interval (s) and the Session Token Timeout (s) will only take effect once the current interval elapses or when the Apache Tomcat servers are restarted.
On the Temp File Settings page, changes to the Temporary Directory Path should be done when the servers are off-line, because some services may lose temporary data. Changing the Temporary Directory Path may leave old temporary files in the former location. The Temporary Directory Path location must exist on disk before changing the path in the AppWorks Gateway. The location on disk must be the same on all nodes in the cluster. The default location is
C:\Program Files\Apache Software Foundation\Tomcat 8.0\tmp.
Note: The location of the Temporary Directory Path must be exclusive to each node in the cluster. It must not be physically accessible or shared by any other node in the cluster.
On the Temp File Settings page, changes to the Temporary File Cleanup Interval (s) will only take effect when the current interval elapses or when the Apache Tomcat servers are restarted.
Note: In most cases, you should not change these settings.
Clients that are connected to one node can also switch to another node and continue functioning.
All nodes must be on the same subnet. They must also be mutually accessible using the User Datagram Protocol (UDP) and through the Transmission Control Procotol (TCP) on port 4000. UDP is used for cluster node discovery and TCP on port 4000 is used for intra-cluster communication.
To deploy AppWorks Gateway in a cluster:
Install and configure Apache Tomcat on each node. For details, see Chapter 1 - Installing the OpenText AppWorks Gateway.
Stop the Apache Tomcat service on each node.
Extract the contents of the
otag-gateway-16.4.zip file to the root of the Apache Tomcat folder on each node. For example,
C:\Program Files\Apache Software Foundation\Tomcat 8.0.
On each node, copy the
<Tomcat_Home>/conf/opentext.properties file from the original node to the
<Tomcat_Home>/conf folder on each of the other nodes.
Optional To override the automatically chosen multicast address and port, type
-Dotag.cluster.mcast.port=<port> at the bottom of the Java Options list in the Java tab of the Apache Tomcat configuration dialog box.
Note: Alternatively, you can override the mulitcast address and port by editing the setenv.sh file, as follows:
export CATALINA_OPTS="$CATALINA_OPTS -Dotag.cluster.mcast.address=<IP_address>"
export CATALINA_OPTS="$CATALINA_OPTS -Dotag.cluster.mcast.port=<port>"
Optional To overwrite the automatically chosen Network Interface on which to broadcast cluster messages, type
-Dotag.cluster.bind.address=<IP_address> at the bottom of the Java Options list.
If the given address is malformed or not found on the host, it is ignored and an error message is delivered to the
gateway.log file. The error message is accompanied by a list of Network Interfaces and bound addresses. Also, an admin alert is sent to the AppWorks Gateway UI, when installed and configured, which the administrator can read when logged in.
Configure a load-balancer in front of the OpenText AppWorks Gateway nodes. When complete, sign in to the OpenText AppWorks Gateway, click Settings, and edit the OTAG Server URL to point to the load-balancer's address.
Note: Repeat this procedure at any time to add nodes to the cluster. They must also be added to the load-balancer.
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