Stuff to memorise… "A method tells an object to perform an action. A property allows us to read or change the settings of the object."

Architecture Planning and designing a successful system Use tried and tested techniques Easy to maintain Robust and long lasting

The DVD Swap Shop Written in VB.NET Suffers from much poor design Available for download from the module web site / blackboard We shall look at a quick demo of what the program does

Security Issues The standard login for the program is User Passwordpassword123 What happens if we use the following? User namehi' or '1'='1

SQL Injection Attacks SQL is a language designed for querying database It stands for Structured Query Language Most commonly abbreviated to SQL or Sequel (as in Sequel Server) We are going to use SQL later in this module and you will be learning it in a parallel module so it won’t do any harm to show you a little SQL now

Concatenation select * from Users where = '" + + "' and UserPassword = '“ + Password + "'" With the following account password123 This concatenates to … select * from Users where = and UserPassword = 'password123'

The Injection Attack select * from Users where = '" + + "' and UserPassword = '" + Password + "'" With the following “account” hi' or '1'='1 This concatenates to … select * from Users where = 'hi' or '1'='1' and UserPassword = 'hi' or '1'='1'

How it Works The single speech mark has terminated the string early Since 1 always equals 1 we return all of the records There are more than zero records so it logs the user in as the first account The first user on any system is often the administrator This is not a lesson on SQL injection attacks it does server to illustrate the vulnerabilities of poor architecture

Maintenance DVD Swap Shop built on Access Not the best choice for an internet application Change to another database e.g. SQL Server DVD.MDB becomes DVD.MDF

The Problem Web page 1 Database Name Web page 2 Database Name Web page 3 Database Name Web page 4 Database Name Data Connection Class Database 100 page site with ten references to the database per page = 1000 changes to the code!

Scalability How many of you have FaceBook or Twitter on your phone? How would we modify the DVD swap shop so there is a phone app that does the same? Re-design the pages However what do we do about the functionality?

Compare the Following Pages

Other Issues to Think About Dealing with International Markets Dealing with Different Computer Platforms

Dealing with International Markets

Amazon Search

Dealing with Different Computer Platforms Mobile Apps - Apple/Android/Windows PCs e.g. iOS / Windows/ Android Linux machines Servers running Apache / IIS What is the technology that makes it possible to support such a range of platforms?

Simple Three Layered Architecture Presentation (Interface) Data Layer Database Middle Tier Business Logic (Objects/Classes)

Benefits : Change Database Technology without Changing the Interface The interface has no knowledge of the structure of the database Middle tier handles communication of data Database technology may be changed with no impact on interface All functionality in the middle tier This means we may bolt on many different interfaces

Benefits : Attach Multiple Presentation Layers Presentation (Interface) Web browser Data Layer Database Middle Tier Business Logic (Objects/Classes) Presentation (Interface) Mobile phone app

Benefits : Code re-use and maintenance All important code is stored in the middle layer Any changes made here benefit all parts of the system using it Code only created once so easier to find an maintain

Overview of Finished Address Book

The Presentation Layer

The Middle Layer

The Data Layer