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Soledad common package
======================
This package contains Soledad bits used by both server and client.
Couch U1DB Backend
------------------
U1DB backends rely on some atomic operations that modify documents contents
and metadata (conflicts, transaction ids and indexes). The only atomic
operation in Couch is a document put, so every u1db atomic operation has to be
mapped to a couch document put.
The atomic operations in the U1DB SQLite reference backend implementation may
be identified by the use of a context manager to access the underlying
database. A listing of the methods involved in each atomic operation are
depiced below. The top-level elements correpond to the atomic operations that
have to be mapped, and items on deeper levels of the list have to be
implemented in a way that all changes will be pushed with just one operation.
* _set_replica_uid
* put_doc:
* _get_doc
* _put_and_update_indexes
* insert/update the document
* insert into transaction log
* delete_doc
* _get_doc
* _put_and_update_indexes
* get_doc_conflicts
* _get_conflicts
* _set_replica_gen_and_trans_id
* _do_set_replica_gen_and_trans_id
* _put_doc_if_newer
* _get_doc
* _validate_source (**)
* _get_replica_gen_and_trans_id
* cases:
* is newer:
* _prune_conflicts (**)
* _has_conflicts
* _delete_conflicts
* _put_and_update_indexes
* same content as:
* _put_and_update_indexes
* conflicted:
* _force_doc_sync_conflict
* _prune_conflicts
* _add_conflict
* _put_and_update_indexes
* _do_set_replica_gen_and_trans_id
* resolve_doc
* _get_doc
* cases:
* doc is superseded
* _put_and_update_indexes
* else
* _add_conflict
* _delete_conflicts
* delete_index
* create_index
Couch views and update functions are used in order to achieve atomicity on the
Couch backend. Transactions are stored in the `u1db_transactions` field of the
couch document. Document's content and conflicted versions are stored as couch
document attachments with names, respectivelly, `u1db_content` and
`u1db_conflicts`.
A map of methods and couch query URI can be found on the `./ddocs/README.txt`
document.
Notes:
* Currently, the couch backend does not implement indexing, so what is
depicted as `_put_and_update_indexes` above will be found as `_put_doc` in
the backend.
* Conflict updates are part of document put using couch update functions,
and as such are part of the same atomic operation as document put.
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