This task documents the creation and use of a temporary runtime directory ".shoal"
Shoal relies on JXTA for it's group communication and organization, as result
JXTA utilizes a persistent store for each group (cluster) created for node
routes and other resources.
The directory is created at startup and contains hierarchical representation of
groups (clusters) created (joined). These directories contain a BTree store of
XML documents describing physical route, communication channels, and other
documents to facilitate cross network connectivity/deployment.
JXTA, in support of large size deployments, it utilize a persistent BTree store
with limited caching to achieve an optimized balanced between memory usage and
in-memory caching of frequently used resources. Note: When deploying a large
cluster, ensure sufficient disk space is available ~10-40KB per node.
Since Shoal defines a deterministic method to create identifiers for groups,
nodes, and communication channel, the persistent store is utilized during the
lifetime of an instance, and therefore the store is expunged during shutdown.
The ".shoal" directory should be treated as transient, and therefore, there is
no need to backup or replicate such data.