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In a standard setup, the XperienCentral application is installed on a single servernode. It is also possible to install XperienCentral on more than one server node in order to create a distributed XperienCentral environment. The principle reasons for creating a clustered XperienCentral environment are:
- Performance: the capacity of the server node which generates pages for visitors of the website and that is used by the editors is insufficient to handle the generated loads.
- Security: For security reasons, the XperienCentral Edit server node is installed on a different server node than the ones that generate pages for the website visitors.
- Failover: To prevent the website from becoming unavailable when one server node goes offline, multiple servers nodes can be configured to ensure that the website keeps running.
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A distributed XperienCentral deployment can contain two or more read/write nodes, all of which have write access to the index and which contain local files for the website as well as several read-only nodes. In order to keep all the files on the servers nodes synchronized with each other, a file store mechanism (the File Distribution Service) is used. The File Distribution Service manages a central store for all files contained in the web roots of the websites in the clustered environment and monitors the creation/deletion of files on a read/write node and then distributes to or deletes the file on all the other nodes.
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- Database configuration
- Write access to the JCRindex
- The sharing of static content
- If you use the File Distribution Service to synchronize files between all the nodes in the cluster, set the maximum allowable file size in the Setup Tool.
Set up the read/write node in the cluster just like it is a standalone setup; there are two differences in setting up a read/write node in a clustered environment compared to setting up a standalone servernode:
- Modify clustering properties in the
settings.xmlfile in order to define the cluster. - Set up the synchronization of static files between the read/write and read-only nodes.
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- The database is already in place: actions related to creating the database do not need to be performed.
- You need to assign each node in the cluster a unique identifier and set the read/write properties in the
settings.xmlfile or - Add two Tomcat startup parameters to identify the server each node in the cluster (cluster ID) and to set the read/write properties.
- Check the firewall settings.
- Start all the servers nodes in the cluster.
Configure the settings.xml Files
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Complete the configuration of the node just like a standalone XperienCentral server node by issuing the following command from a Command prompt:
mvn –s settings.xml –P configure-jcr-repository
Clustering-specific Settings for all
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Nodes
Once the read/write node is running properly, use its settings.xml for the other read/write node (if you have a dual read/write node environment) as well as for all the read-only node(s). Two properties in the settings.xml of the read/write node have to be changed for the other read/write node (if you are setting up a dual read/write node cluster) as well as for the read-only node(s):
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Finish the configuration of the node just like a standalone XperienCentral server node by issuing the following command from a command line prompt:mvn –s settings.xml –P configure-jcr-repository
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Make Static Content Available to all
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Nodes
When an editor places an image on a page within XperienCentral, this image will initially be only available on the read/write node on which it was placed. Through the use of a file store mechanism (The File Distribution Service), XperienCentral synchronizes static content between all the read/write nodes and read-only nodes in the cluster.
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The Tomcat servlet container on every server node needs to know whether it should startup as a read/write node or a read-only node. This can be defined in the Java runtime options of Tomcat. To change the startup parameters of Tomcat, click the “Monitor Tomcat” icon in the system tray. After activating the Monitor, a pop-up appears. Switch to the [Java] tab.
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The setting max_allowed_packet should be set to a value higher than the largest file that exists or can exist in the web root directory. Additionally, the XperienCentral server node and the MySQL server node must be able to handle the largest file on the file system. Because MySQL stores the complete file in memory, you could encounter out of memory errors if this setting is set too low. For more information, see the MySQL documentation for the max_allowed_packet property.
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| From | To | Protocol | Description |
|---|---|---|---|
| read/write + read-only(s) | database | DB protocol | The connection between the read/write and read-only node(s) to the database server to make for performing queries. |
| read/write node | read-only node | XperienCentral File Distribution Service or file synchronization mechanism such as Robocopy or RsyncS. | To synchronize files between all nodes in the clustered environment. |
| Internet | read-only node | HTTP | To handle page requests from the frontend. |
| Intranet + VPN | read/write node | HTTP | Access to the editors' read/write node(s). |
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