wiki:BluePrint/Synchronisation

Version 17 (modified by Fran Boon, 16 years ago) ( diff )

This works well, but has some needed enhancements

Blueprint for Synchronisation

We need to be able to support synchronising data between instances:

All tables have UUID fields: DeveloperGuidelinesDatabaseSynchronization

We can Export the tables - CSV is best-supported within Web2Py currently
"complete database backup/restore with db.export_to_csv_file(..),db.import_from_csv_file(...),
reimporting optionally fixes references without need for uuid"

This can be done using appadmin, but we have started work on a user-friendly way of dumping all relevant tables:

  • controllers/default.py
  • views/default/export_data.html
  • views/default/import_data.html

This works well, but has some needed enhancements:

  • Define how to deal with duplicates (currently, if a UUID is duplicated then the CSV file Updates the record, if a UUID isn't present then it is Created)
  • Download all
  • Download all for a Module

Need clear list of which tables to include:

  • not lookup lists which are the same across sites
    • e.g. OpenStreetMap/Google Layers (but WMS/SOS Layers Yes. Shapefiles Layers Yes if uploads copied across as well)
  • not site-specific stuff such as system_config, gis_keys, etc

Create an index manually to make the search by uuid faster.

other related threads:

There is a simple 1-table example appliance which has the ability to do syncs via XML-RPC:

In Sahana2 the record ids are UUIDs built from each instance's 'base_uuid'

There is a sync_instance table: 

CREATE TABLE sync_instance (
    base_uuid VARCHAR(4) NOT NULL, -- Instance id
    owner VARCHAR(100), -- Instance owner's name
    contact TEXT, -- Contact details of the instance owner
    url VARCHAR(100) DEFAULT NULL, -- Server url if exists
    last_update TIMESTAMP NOT NULL, -- Last Time sync with the instance
    sync_count INT DEFAULT 0, -- Number of times synchronized
    PRIMARY KEY(base_uuid)
);
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