defensive design- Marko Deguzman

defensive design- Marko Deguzman

1. ensure the code is easy and well maintained

   • they will do this by aniticipating how the user might misuse the program
     • reduce the number of errors thre are in the code

2. authentication can help protect your programs as the make sure the person accessing

3. there are two ways to preventing users from entering something you dont want in your code:

   • input sanitation - removing any unwanteed characters before passing data through the program
   • input validation - checking if data meets certain criteria before passing it into the program e.g. checking if the email address contains @ or . com
   • Sanitation and validation are often done using:
     • White lists - a list if all data that a program should accept
     • Black list - a list of data that a program shouldnt accept

4. testing

   • when writing a program, you should test the program to identify errors within it. these are
     • Logic errors - when the compiler or interpreter is able to run the program, but the program does something does something unexpected
     • syntax errors- when the compiler or interpreter doesn't understand something you've typed because it doesn't follow the rules or grammar
       • these are diagnosed by the compilers and interpreters
   • there are different types of testing, these include -
     • final testing - the program goes through the development cycle once and all the required features of the program are added at the same time.
     • iterative testing - the program will go through the development a few times.
   • a test plan will outline what you're going to test and how you're going to test it, you could use multiple types of data -
     • normal data - things that is likely to be inputted into the program
     • extreme (Boundary) data - values at the limit of what a program should be able to handle
     • erroneous data - inputs that the program shouldn't accept

5. Translators

   • Translators are needed in any computer to process any computer language into machine code
     • types of code include :
       • High level language - one instruction of high level code represents many instructions in of machine code. This code is universal, working on many machines. However this must be translate into low level language
       • Low Level language - one instruction represents one machine code. This is only usually written for one type of machine or processor. This is more memory efficient and is faster
     • Types of translators include:
       • compiler - translates all of the source code and creates one executable file. only needed once. returns a list of errors once compiling is completed. However compiling takes a long time
       • Interpreter - translates and runs the source code one instruction at a time but doesn't create an executable file. needed everytime when you want to run the program. will find the first error and then stop