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Learning Karaf Cellar

You're reading from   Learning Karaf Cellar Build and implement a complete clustering solution for the Apache Karaf OSGi container

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Product type Paperback
Published in Jul 2014
Publisher
ISBN-13 9781783984602
Length 124 pages
Edition 1st Edition
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Authors (2):
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Jean Baptiste Onofre Jean Baptiste Onofre
Author Profile Icon Jean Baptiste Onofre
Jean Baptiste Onofre
Jean-Baptiste Onofré Jean-Baptiste Onofré
Author Profile Icon Jean-Baptiste Onofré
Jean-Baptiste Onofré
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Toc

Distributed cluster resource states

Cellar uses Hazelcast to maintain and store the states of the different resources in the cluster (bundles, features, configuration, OBR, eventadmin, DOSGi, and so on). To do so, Cellar uses Hazelcast's distributed data structures. Thanks to this, the cluster data is distributed across all the nodes in the cluster. Each Cellar node stores a portion of the data (and eventually the replicas/backups).

For instance, in Cellar, you have the following three features installed:

  • Feature A
  • Feature B
  • Feature C

The statuses of the features are stored in a distributed map that looks similar to the following statuses:

  • Feature A: Installed
  • Feature B: Uninstalled
  • Feature C: Installed

The partition of the features' distributed map (in the cluster) can be as follows:

  • Feature A's status on node1
  • Feature B's status on node2
  • Feature C's status on node1

If a node goes down or leaves the cluster, Hazelcast redistributes the data (including the replica) on the remaining...

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