This page hosts the detailed specification for the [https://blueprints.launchpad.net/sahana3/+spec/synchronisation Blueprint for the Synchronisation].

We need to be able to support synchronising data between instances:
 * http://wiki.sahana.lk/doku.php?id=doc:sync:english

The UUIDs have already been configured: DeveloperGuidelinesDatabaseSynchronization

We need to extend this by Exporting the tables (CSV is best-supported within Web2Py currently)[[BR]]
"complete database backup/restore with db.export_to_csv_file(..),db.import_from_csv_file(...),[[BR]]
reimporting optionally fixes references without need for uuid"
 * http://groups.google.com/group/web2py/browse_thread/thread/c08d1b05ddda672c
 * http://groups.google.com/group/web2py/browse_thread/thread/be927ccf4d9745d2/637e45ccc2cf2583
 * http://groups.google.com/group/web2py/browse_thread/thread/55d923a51eca2c90

Initially this can be done using appadmin, but we want to make a user-friendly way of dumping all relevant tables. (Need clear list of which tables to include - e.g. not lookup lists which are the same across sites, not site-specific stuff such as system_config, gis_keys, etc)

Export tables as CSV (in Controller):
{{{
def export():
    s=StringIO.StringIO()
    db.export_to_csv_file(s)
    response.headers['Content-Type']='text/csv'
    return s.getvalue() 
}}}

Import tables at the other end:
{{{
def import_and_sync():
    form=FORM(INPUT(_type='file',_name='data'),INPUT(_type='submit'))
    if form.accepts(request.vars):
        db.import_from_csv_file(form.vars.data.file)
        # for every table
        for table in db.tables:
        # for every uuid, delete all but the most recent
            items=db(db[table].id>0).select(db[table].id,db[table].uuid,orderby=~db[table].modified_on,groupby=db[table].uuid)
            for item in items:
                db((db[table].uuid==item.uuid)&(db[table].id!=item.id)).delete()
    return dict(form=form) 
}}}

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

other related threads:
 * http://groups.google.com/group/web2py/browse_thread/thread/af3f7ad5271a10c6/c5e96141c13a29ad
 * http://groups.google.com/group/web2py/browse_thread/thread/7d639c98b5b8dcd2/c0fe17ccbdd12eb7

There is a simple 1-table example appliance which has the ability to do syncs via XML-RPC:
 * http://mdp.cti.depaul.edu/appliances/default/download/app.source.312926207134.txt


In S2 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)
);
}}}