Chetan Mehrotra created OAK-3402:
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Summary: Multiplexing DocumentStore support in Oak layer
Key: OAK-3402
URL: https://issues.apache.org/jira/browse/OAK-3402
Project: Jackrabbit Oak
Issue Type: Story
Reporter: Chetan Mehrotra
Supporting multiplexing repository would have impact on various places in Oak
design. There are various sub components in Oak which maintain there own
storage built on top of NodeStore. For e.g. indexes are stored within
NodeStore, permissions are also stored within NodeStore. Adding multiplexing
support would impact such stores in following ways
The most basic application of multiplexing support is to support private and
shared storage. Under this an Oak application would have a private store and a
shared store. Content under certain paths would be stored under private repo
while all other content is stored under shared repo
# *Writing* - Any content written via JCR API passes through some
{{CommitHooks}}. These hooks are responsible for updating the indexes,
permission store etc. Now if any path say /foo/bar gets modified the commits
hooks would need to determine under which path in NodeStore should the derived
data (index entries, permission etc) should be stored. For simple case of
private and shared store where we have 2 sets of paths private and shared these
hooks would need to be aware of that and use different path in NodeStore to
store the derived content. Key point to note here that any such storage has to
differentiate wether the path from which the content is being derived is a
private path or shared path
# *Reading* - Reading requirement compliments the writing problem. While
performing any JCR operation Oak might need to invoke QueryIndex,
PermissionStore etc. These stores in turn would need to perform a read from
there storage area within NodeStore. For multiplexing support these components
would then need to be aware that there storage can exist in both shared and
private stores
h4. Terms Used
# _private repo_ (PR) - Set of paths which are considered private to the
application. Tentative example /lib,/apps
# _shared repo_ (SR) - Set of paths which are considered shared and different
versions of the application can perform read and write operations on them.
Tentative example /content, /etc/workflow/instances
# {{PathToStoreMapper}} - Responsible for mapping a path to store type. For now
it can just answer either PR or SR. But the concept can be generalized
Aim of this story is to prototype changes in Oak layer in a fork to asses the
impact on current implementation
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