Defensive Design

Defensive Design

1. How do you know when your defensive design isn't good enough?

   • When it Crashes
   • When it behaves in an unintended fashion
   • When Data Security has been compromised.

2. Input that Defensive Designs need

   • A username / password entry
   • Contact Details
   • Current Date
   • Input (Eg. Search Box)
   • Building up a shopping cart
   • Entering Data into a database

3. Defensive design is the practice of anticipating every possible way that an end-user could misuse a system or device. During the defensive design process, methods are put in place to eliminate misuse. If this is not completely possible then it will aim to minimise the negative consequences.

   • The first port of call in defensive design is to decide on what kind of user interface to code for. There is a fine balancing act with giving the user access to all the information and abilities that they might need, while at the same time imposing limits on the things that they commonly get wrong.
     • A hard-coded menu is difficult if not impossible for the user to get wrong, but at times more flexibility is required. A good compromise is to accept information through graphical widgets, rather than input text.

4. How to check is the data is valid.

   • Checking and limiting the Length of the data
   • Checking the Range of the data
   • Checking the Type of the data
   • Checking the Format of the data

5. If the validation rule breaks. How would you inform the user

   • Inform the user of the problem and allow them to re-enter the data
   • Modify the input to fit the rules. For example - cut off (truncate) the excess characters if it is too long, or pad it out if it is too short.