1. Introduction to Cyberspace
Joel crichlow, ph.d.

2. We will talk about:
A definition of Cyberspace
Cloud Computing
The Computer Network
Some Services
Key Design Issues
Software Architecture

3. What is Cyberspace?
The communication environment supported by computer networks.
Cloud

4. Cloud computing Pay-per-use service alias Pay-as-you-go model
Uses a multi-tenant architecture to deliver several categories of service
Software as a Service (SaaS)
Delivers a single application
Platform as a Service (PaaS)
Delivers development environments
Infrastructure as a Service (Iaas)
Delivers storage, virtual machines, etc

5. The Computer Network Hosts and Communications Subnet
WAN – Wide Area Network
LAN – Local Area Network
PSNs – Packet Switching Nodes
switches, hubs, bridges, gateways, routers
Computer network
(hidden) network
User’s computer

6. The Computer Network Protocols
Arpanet – Advanced Research Projects Agency Network
Internet
ISO/OSI – International Organization for Standardization/Open Systems Interconnection
TCP/IP – Transmission Control Protocol/Internet Protocol
Computer network
(hidden) network
User’s computer

7. Protocols

8. Services Email and Messaging WWW DNS – Domain Name System
SMTP – Simple Mail Transfer Protocol
TCP/IP – Transmission Control Protocol/Internet Protocol
WWW
HTML – HyperText Markup Language
HTTP – HyperText Transfer Protocol
XML – eXtensible Markup Language

9. Domain Naming system

10. Html web display

11. Html file

12. Services Social Networking
Facebook, Twitter, LinkedIn
Short Message Service (SMS)
Open source software
LAMP web application software stack
Linux, Apache, MySQL and PHP
In-house development
HipHop, Thrift and Cassandra
Memcached: a distributed memory caching system

13. Services
Social networking

14. Services Multimedia Transfer Distributed Computation
MPEG – Motion Picture Experts Group
MP3 - MPEG Audio Layer 3
Distributed Computation

15. Services Distributed Transaction Processing network Transaction trans
manager
Replica
network
trans
Data
database

16. Services E-Commerce Request 1 2 3 4 5 payer payee Acquiring
institution
Issuing
Flow of money
network
authorization
Payment order
notification
Request 1 2 3 4 5

17. Services Distributed Real-Time Processing Sensor Dev ice Comp Actuator
Network

18. Issues Naming Sharing Availability and reliability Replication
Globally unique, Domains, Location
Sharing
Authentication, Access rights
Scheduling, Coordinating, Synchronizing
Resolving conflicts
Availability and reliability
Up-time, Responsive, Correct
Replication
Copies made and stored at separate sites
Load sharing, Improved throughput, Improved availability

19. Issues Privacy and Security Communication
Passwords, Access Control Lists, Capabilities
Encryption, Memory Protection
Intrusion blockers
Communication
Protocols aplenty
Concurrency and Synchronization
Race Conditions
Critical Regions
Locks

20. Issues Time and Coordination Fault Tolerance and Recovery
What is the time?
Ordering of events
Fault Tolerance and Recovery
Redundant elements
Logging schemes
Back-ups
Time-outs
Retransmissions

21. Issues Scalability User-System Interface
Cannot assume a static configuration
Plan for growth
How about reduction?
User-System Interface
Look and Feel

22. Software architecture Process Groups
Process – The executing program
Messages must be delivered to all the processes
Activities of the processes must be synchronized
Group Membership
Membership List
Join
Leave

23. Software Architecture Client-Server
For example:
A database
Shared
resource
Server
Workstations
Client
Network
Client
Client
Client

24. Software architecture P2P: peer-to-peer
Symmetrical Arrangement
peer
peer
client
client
client
client
client
Server
Server
network
For example: File sharing

25. We covered:
A definition of Cyberspace
Cloud Computing
The Computer Network
Some Services
Key Design Issues
Software Architecture