Introduction to Cyberspace Joel Crichlow Ph D Contents

Introduction to Cyberspace Joel Crichlow, Ph. D.

Contents q q q 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 (Saa. S) ◦ Delivers a single application Platform as a Service (Paa. S) ◦ 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 – Hyper. Text Markup Language ◦ HTTP – Hyper. Text Transfer Protocol ◦ XML – e. Xtensible Markup Language

Domain Naming system

Html web display

Html file

Services Social Networking Facebook, Twitter, Linked. In Short Message Service (SMS) Open source software LAMP web application software stack ◦ Linux, Apache, My. SQL and PHP In-house development ◦ Hip. Hop, Thrift and Cassandra Memcached: a distributed memory caching system

Services Social networking

Services Multimedia Transfer ◦ MPEG – Motion Picture Experts Group ◦ MP 3 - MPEG Audio Layer 3

Services Distributed Computation

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

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

Services Distributed Real-Time Processing Device Actuator Dev ice Sensor Actuator Sensor 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

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

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

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

Software architecture P 2 P: peer-to-peer Symmetrical Arrangement peer client client Server network For example: File sharing Server

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