Visualization Of Changing Data

Hello,
I'm working on a distributed application which requires data from a central database to be shown to various users. In particular users should be able to open "views" on the database, specifying the data they are interested in, and being shown the result.

This can be easily accomplished modeling the view specifications as SQL select queries, sending those queries to the server, and visualizing the result. This approach is very flexible, supported, fast and definitely the way we would like to implement it.

The problem is that we have an additional requirement.
In general the data the users might be interested in is not static, and when that data changes, those changes should be propagated to the client views.

There are lots of solutions and technologies aimed to solve very similar problems, but no one seems to support this scenario well.

1. You can re-run the queries every x time (polling)... but this is hardly an option when you have hundreds of client-views that require data to be updated in real-time (so "x time" should be, say, 1 second).

2. You can use query notification... but the documentation explicitily says it doesn't scale well and shouldn't be used with a large number of clients (which is exactly what is needed in this case).

3. You can use replication services... but this technology doesn't really seem to be created to support this scenario.

4. You can use notification services... but even this technology seems to be focused on different scenarios. I haven't looked at it extensively anyway.

5. You can use DML triggers to track data changes... but you still don't have the publish-subscribe mechanism to register client views and the mechanism to know which client views are affected by the changes.

6. You can implement a business logic tier that relates modification requests to client views... and basically do everything from scratch without using existing services.

What are your opinions?


Thank you,

Lorenzo Castelli