We currently have a centralised web app and database (running on glassfish and oracle) which is accessed from multiple stations distributed about the country.
At the stations there is data entered into and read from the system (through the browser).
When the (external) connection goes down between the station and the centralized web app we would like for the stations to continue to function – store and present data, then when the connection returns the data is pushed back into the central server maintaining database integrity.
Given that we would be willing to change our app server or database if it was worth it, how is this best handled, is there any out of the box solution for this?
Install the servers at the individual locations, replicate what you want to share across them “routinely”, and leave all of the other centralized, but non-vital tasks (like, say, reporting) on the central system.
There is not “out of the box” solution. You system is centralized for whatever reason it’s centralized. You’re asking for it to be decentralized. By doing so you need to reconsider why it’s centralized in the first place, and what dependencies there are because of that centralization (such as each site having instant access to data at all of the other sites).
Address those issues of what you can do without, for how long, and how to share it, and then you can set up autonomous sites. The magnitude and complexity of this process is dependent upon you application and the services it supplies to the remote users.