Java validating data fatpeopledating com
Of course neither this method, nor N-Version programming can detect when all the versions are in error.
Also the decision algorithm could have bugs in it, so though in some ways I find this approach to safety critical systems reassuring, it is far from foolproof (of course I am not going to think about this the next time I step into an airliner).
The database level validation is necessary, but not sufficient for building effective and usable systems.
Of course, when you are updating data external to your organization (say placing an order over web service), then clearly the handling of errors raised by the web service must be handled in an application.
More significantly, if we want to build usable systems then we have to put validation in the user interface.
We tend to think of validation as something that constrains or inhibits the user; but used effectively it can help users to avoid making mistakes in the first place, and provide useful advice for correcting errors that occur.
We therefore need to look at what the implications of these discrepancies in the logic might be.
For the sake of illustration, we will assume a system with validation repeated in the user interface, the middleware and the database.
Database error messages are generally considered to be unfriendly by users and programmers, but this need not be the case.You just need to make a rule that the database is only allowed to be updated over particular routines in the middle ware.The problem with this argument is that you are now dependent upon a manual rule to enforce the validation.If we just rely on the database (or the middleware for that matter) to apply validation then the user won’t know that a problem has occurred until they send the data over the network.This is not just user unfriendly, but may have performance implications too.