1. What is System Design?
In System design, we use the requirements we developed in system analysis to create a blueprint of the future system
Successful design builds on what we have learned in analysis and transforms that knowledge into a working system.
Design is still planning as the system need not be developed during this phase.

2. Design Strategies Custom development (build from scratch)
Purchase and customize
Outsource development

3. Custom Development PROS CONS Allows flexibility and creativity
Builds technical skills and functional knowledge in-house
Best ‘fit’
CONS
Requires significant time and effort
May exacerbate existing backlogs
May require missing skills
Often costs more
Often takes more time
Risk of project failure

4. Packaged Software Include small single-function tools
All-encompassing enterprise resource planning (ERP) systems
Rarely a perfect fit with business needs
May allow for customization
Manipulation of system parameters
Changing way features work
Synchronizing with other application interfaces

5. Outsourcing Hiring an external vendor, developer, or service provider
May reduce costs or add value
Risks include possibly
Losing confidential information
Losing control over future development
Losing control over future cost structure
Losing learning opportunities

6. Outsourcing Contracts
There are Three types:
Time and Arrangement:
Pay for what is needed to get job done. Flexible but risk of large bill at the end.
Fixed-price
Certainty regarding payment but very little flexibility in delivering IS support. ‘You get what you ask for.’
Value-added
Outsourcer shares in benefits gained from the system.

7. Selecting a Design Strategy
Consider each of the following:
Business need
In-house experience
Project skills
Project management
Time frame

8. Key Definitions
The architecture design consists of plans for the hardware, software, communications, security , and global support for the new application
The designers must decide if processing will occur in the server (server-based), at the personal computer (client-based), or in some combination of these (client-server based).

9. Key Definitions
The network model shows major components of the system, where they are located and how they will be connected to one another.
The hardware and software specifications describe these components in detail and aid those responsible for purchase and acquisition of these products.

10. Architectures Server based Client based Client-server based
thick versus thin client
cloud computing

11. Server-Based Computing (and, essentially, Thin-Client Computing)

12. Client-Based Computing

13. Client-Server-Based Computing

14. Client-Server Attributes
Typical Pros
Compatible with web-based system design
Scaleable
Work with multiple vendors/products
No central point of failure
Typical Cons/Limits
Complexity
New programming languages and techniques (stress for personnel)
More complex to update

15. Identifying Threats to the System
A threat is any potential adverse occurrence that can do harm to the application or its data
Threats come from internal as well as external sources
Categories of threats
Disruptions, destruction and disaster
Viruses fall into this category
Unauthorized access

16. Most Common Threats

17. Creating Controls
A control is something that mitigates or stops a threat
Controls include
redundancy
fault tolerant servers
disaster recovery plans
anti-virus software

18. Additional Controls Include
A security policy
‘Social Engineering’
Passwords and encryption
What you have
What you know
What you are
Firewalls
wired, wireless controls

19. Current Threats Malware Delivery Software Updates
Banner Ads (‘malvertising’)
Downloadable documents
Man-in-the-middle
Keyloggers

20. The threat of open WiFi ‘Sidejacking’
packet sniffers intercept traffic between two html parties and steal the session cookie
Firesheep is an application that supports this as an extension of the Firefox browser
requires Firefox browser use
cannot read https sessions
Faceniff is a similar application for Android phones and tablets

21. A Little Exercise…