introduction to cyberspace joel crichlow, ph.d.. we will talk about: a definition of cyberspace ...
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Introduction to Cyberspace
Joel Crichlow, Ph.D.
We will talk about: A definition of Cyberspace Cloud Computing The Computer Network Some Services Key Design Issues Software Architecture
What is Cyberspace? The communication environment supported by computer networks.
Cloud
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
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
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
Protocols
Services
Email and Messaging◦ 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
Domain Naming system
Html web display
Dr. Joel Crichlow
Office Address: Computer Science, Robinson Hall Rowan University Glassboro , NJ 08028 Office: (856) 256-4500 ext 3278 Fax: (856) 256-4741 Email: [email protected]
Qualifications, Awards and Attachments | Employment History | Research | Publications | More
Html file<HEADER> <TITLE>Joel Crichlow</TITLE></HEADER> <BODY> <p> <H1>Dr. Joel Crichlow</H1> <P> <HR><HR> Office Address: <BR> <DL><DD> <EM>Computer Science, Robinson Hall</EM> <br> <EM><a href="http://www.rowan.edu">Rowan University</a></EM> <BR> <EM>Glassboro , <A HREF="http://dir.yahoo.com/Regional/U_S__States/New_Jersey/" >NJ</A> 08028</EM> <BR> Office: <EM>(856) 256-4500 ext 3278</EM> <BR> Fax: <EM>(856) 256-4741</EM> <BR> Email: <EM>[email protected]</EM> </DL> <P> <a href="http://elvis.rowan.edu/~crichlow/Qualifications.htm">Qualifications, Awards and Attachments</a> | <a href="http://elvis.row an.edu/~crichlow/Employment.htm">Employment History</a> | <a href="http://elvis.rowan.edu/~crichlow/Research.htm">Research</a> | <a href="http://elvis.rowan.edu/~crichlow/Publications.htm">Publications</a> | <a href="http://elvis.rowan.edu/~crichlow/more.htm">More </a>
ServicesSocial 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
ServicesSocial networking
Users/Browsers/
Web Clients
Web Servers
Distributed Database
Services Multimedia Transfer
◦ MPEG – Motion Picture Experts Group◦ MP3 - MPEG Audio Layer 3
Distributed Computation
Distributed applications
DCM middleware
Host OS and network service
Distributed applications
DCM middleware
Host OS and network service
Services Distributed Transaction Processing
Transaction
manager
Replica
manager
Transaction
manager
Replica
manager
network
trans trans
Data
manager
Data
manager
database database
Services E-Commerce
payer payee
Acquiring
institution
Issuing
institution
Flow of money
network authorization
Payment order
notification
Request
1
2
3
4
5
Services Distributed Real-Time Processing
Dev ice
Comp
Sensor Actuator
Device
Comp
Sensor Actuator
Device
Comp
Network
Issues
Naming◦ 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
Issues Privacy and Security
◦ Passwords, Access Control Lists, Capabilities◦ Encryption, Memory Protection◦ Intrusion blockers
Communication◦ Protocols aplenty
Concurrency and Synchronization◦ Race Conditions◦ Critical Regions◦ Locks
Issues Time and Coordination
◦ What is the time?◦ Ordering of events
Fault Tolerance and Recovery◦ Redundant elements◦ Logging schemes◦ Back-ups◦ Time-outs◦ Retransmissions
IssuesScalability
◦ Cannot assume a static configuration◦ Plan for growth◦ How about reduction?
User-System Interface◦ Look and Feel
Software architectureProcess 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
Software ArchitectureClient-Server
NetworkClient
ServerClient
Client
Client
Shared
resourceWorkstations
For example:A database
Software architectureP2P: peer-to-peer
client client
Server
client client
Server
client
network
peerpeer
Symmetrical Arrangement
For example: File sharing
We covered: A definition of Cyberspace Cloud Computing The Computer Network Some Services Key Design Issues Software Architecture