The most interesting talk at the recent Oracle Spatial SIG was the one about the second phase of the Ordnance Survey's project magnesium This is the second phase of a research project looking at interoperability technologies, and as you can see from the presentation was based around using an OGC Transactional Web Feature Service (WFS-T), to receive regular COU updates from O.S. and to apply these to a central database.

This is a really cool idea, but it got me wondering whether this is something you'd really want to do in this way or if WFS-T is the best thing for this. The idea seemed to be that you could subscribe to a service and then recieve periodic updates of COU.

If I was an O.S. customer i think I'd like to see this done in two slightly different ways.

If I was wanting regular updates, say weekly or daily, rather than subscribe to a push service, i'd want a pull service where i could set my systems up to go and grab the update at a time of my convenience from the O.S. servers, by downloading it and then applying it automatically to my central data store. I wouldn't necessarily need a wfs service here, its actually something much a simpler, a url to the update file and a log-on to the server.  It could utilise RSS to let me know when the updates were ready. The update file could be exactly the same as i receive now from O.S. by mail or ftp. Back when map manager was first released, it had a greyed out tool that said something like "download COU", i don't think its still there, as there was never the back end service to support it.

The second option which would utilise WFS-T would be for real-time updates. I'd like to subscribe to a service that would push individual feature updates to me as and when they happened, I'd publish a WFS-T then O.S. would push all changes as they happened. This would reduce the data size of individual transactions, but would place a much higher burden on me having my systems and service in place 24/7

The final issue is whether or not I'd really want the service to update my database automatically, or whether I'd want to QC the updates first, or make decisions about what it would mean for my Data. I think on the whole I'd probably like to apply the changes to a versioned database and then decide whether to post them to the master.

There's a whole bunch of things that need to be in place before any of this could become reality, I'd want to know who was sending me updates, and that they had not been tampered with, or gone missing. O.S. would want to know that it was really me receiving them and that i was entitled to them. There would need to be in place suitable authentication, encryption and rights management for the data. All of this is possible at the moment but its probably a big undertaking to get this in-place anytime soon.

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