Review

Secondary Memory DevicesInformation is movedbetween main memoryand secondary memoryas needed

CentralProcessing

Unit

MainMemory

Floppy Disk

Hard Disk

Secondary memorydevices providelong-term storage

Hard disksFloppy disksZIP disksWritable CDsWritable DVDsTapes

A Computer Specification

• Consider the following specification for a personal computer:

– 2.8 GHz Pentium 4 Processor– 512 MB RAM– 80 GB Hard Disk– 48x CD-RW / DVD-ROM Combo Drive – 17” Video Display with 1280 x 1024 resolution– 56 Kb/s Modem

• What does it all mean?

Software Categories

• Operating System– controls all machine activities– provides the user interface to the computer– manages resources such as the CPU and memory– Windows XP, Unix, Linux, Mac OS

• Application program– generic term for any other kind of software– word processors, missile control systems, games

• Most operating systems and application programs have a graphical user interface (GUI)

Memory

Main memory is divided into many memory locations (or cells)

927892799280928192829283928492859286

Each memory cell has a numeric address, which uniquely identifies it

Remember this?

Storage Capacity• Every memory device has a storage capacity, indicating the number of bytes it can hold

• Capacities are expressed in various units:

-Character, Field, Record, File

KB 210 = 1024

MB 220 (over 1 million)

GB 230 (over 1 billion)

TB 240 (over 1 trillion)

Unit Symbol Number of Bytes

kilobyte

megabyte

gigabyte

terabyte

Bit Combinations

• Each combination can represent a particular item

• There are 2N combinations of N bits

• Therefore, N bits are needed to represent 2N unique items

21 = 2 items

22 = 4 items

23 = 8 items

24 = 16 items

25 = 32 items

1 bit ?

2 bits ?

3 bits ?

4 bits ?

5 bits ?

How manyitems can be

represented by

The Central Processing Unit (CPU)

• A CPU is on a chip called a microprocessor

• It continuously follows the fetch-decode-execute cycle:

fetch

Retrieve an instruction from main memory

decode

Determine what theinstruction is

execute

Carry out theinstruction

The Central Processing Unit

• The CPU contains:

Arithmetic / Logic Unit

Registers

Control Unit

Small storage areas

Performs calculations and makes decisions

Coordinates processing steps

• The Internet was created by the Advanced Research Projects Agency (ARPA) and the U.S. Department of Defense for scientific and military communications.

• The Internet is a network of interconnected networks. Even if part of its infrastructure was destroyed, data could flow through the remaining networks.

• The Internet uses high-speed data lines, called backbones, to carry data. Smaller networks connect to the backbone, enabling any user on any network to exchange data with any other user.

• ARPANET, NSFnet, Internet• Internetworking: the process of connecting separate

networks

The Internet: Then and Now

• Every computer and network on the Internet uses the same protocols (rules and procedures) to control timing and data format.

• The protocol used by the Internet is the Transmission Control Protocol/Internet Protocol, or TCP/IP.

• No matter what type of computer system you connect to the Internet, if it uses TCP/IP, it can exchange data with any other type of computer.

How the Internet Works - TCP/IP

• Most computers don't connect directly to the Internet. Instead, they connect to a smaller network that is connected to the Internet backbone.

• The Internet includes thousands of host computers (servers), which provide data and services as requested by client systems.

• When you use the Internet, your PC (a client) requests data from a host system. The request and data are broken into packets and travel across multiple networks before being reassembled at their

destination.

How the Internet Works - Routing Traffic Across the Internet

• In order to communicate across the Internet, a computer must have a unique address.

• Every computer on the Internet has a unique numeric identifier, called an Internet Protocol (IP) address.

• Each IP address has four parts – each part a number between 0 and 255. An IP address might

look like this: 205.46.117.104.

How the Internet Works - Addressing Schemes

Protocol LayerComments

Application Protocols LayerProtocols specific to applications such as WWW, e-mail, FTP, etc.

Transmission Control Protocol Layer

TCP directs packets to a specific application on a computer using a port number.

Internet Protocol Layer

IP directs packets to a specific computer using an IP address.

Hardware Layer Converts binary packet data to network signals and back.(E.g. ethernet network card, modem for phone lines, etc.)

• In addition to an IP address, most Internet hosts or servers have a Domain Name System (DNS) address, which uses words.

• A domain name identifies the type of institution that owns the computer. An Internet server owned by IBM might have the domain name ibm.com.

• Some enterprises have multiple servers, and identify them with subdomains, such as products.ibm.com.

How the Internet Works - Domains and Subdomains

• The World Wide Web is a part of the Internet, which supports hypertext documents, allowing users to view and navigate different types of data.

• A Web page is a document encoded with hypertext markup language (HTML) tags.

• HTML allows designers to link content together via hyperlinks.

• Every Web page has an address, a Uniform Resource Locator (URL).

Major Features of the Internet -The World Wide Web

• File transfer protocol (FTP) is the Internet tool used to copy files from one computer to another.

• Using a special FTP program or a Web browser, you can log into an FTP host computer over the

Internet and copy files onto your computer.

• FTP is handy for finding and copying software files, articles, and other types of data. Universities and software companies use FTP servers to provide visitors

with access to data.

Major Features of the Internet - File Transfer Protocol (FTP)

• Telnet is a specialized service that lets you use one computer to access the contents of another computer – a Telnet host.

• A Telnet program creates a "window" into the host so you can access files, issue commands, and exchange data.

• Telnet is widely used by libraries, to allow visitors to look up information, find articles, and so on.

Major Features of the Internet - Telnet

The Knowledge Management System Cycle

Create knowledge . Knowledge is created as people determine new ways of doing thing or develop know-how. Sometimes external knowledge is brought in.Capture knowledge. New knowledge must be identified as valuable and be represented in a reasonable way.Refine knowledge. New knowledge must be placed in context so that it is actionable . This is where human insight (tacit qualities) must be captured along with explicit facts.Store knowledge. Useful knowledge must then be stored in a repository so that others in the organization can access it. Manage knowledge. Like a library, the knowledge must be kept current. It must be reviewed to verify that it is relevant and accurate.Disseminate knowledge. Knowledge must be made available in a useful format to anyone in the organization who needs it, anywhere and any time.

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Properties of a DMSDocument Management Web Technologies

Manage large amounts of material Deliver multiple mediaProvide consistent and predictablestructure

Provide user interface and navigation

Enable hyper-linkingEnsure currencyFacilitate non-technical authors withtemplates

Facilitate non-technical authors withWYSIWYG tools

Support roles, responsibilities andaccess controlEnable workflowPublish multiple viewsEnable version controlProvide document lockingEnable recording of attributes Enable attribute searching using meta-tagsStable, well-defined functionality Continuously evolving

Components of a DMS

• Metadata• Integration• Capture• Indexing• Storage• Retrieval• Distribution• Security• Workflow • Collaboration• Versioning

DefinitionsDefinitions• A document is an artifact resulting from the

transformation of a set of ideas by people following a set of processes.

• An electronic document has the following characteristics (Sprague, 1995):– holds information of multiple media: text, graphics,

audio, video– contains multiple structures: headers, footers, TOC,

sections, paragraphs, tables– is dynamic: can be updated on the fly– may depend on other documents

DefinitionsDefinitions

– Process: Decision making process, design process, etc.– Input: Thoughts, ideas, issues, concerns– Output: Documents (memos, news, design documents, white

papers, marketing literature, contracts, manuals)– People: Executives, Designers, Lawyers, Scientists

Process

Technology

Input Output

People

Change

Technologyenables change

in process

BenefitsBenefits• Document Management Systems (DMS) enable:

– Generation of revenue producing products• For publishing industry, documents are a direct source of revenue

– Organizational Communication• Concepts, ideas, decisions are shared in the form of electronic

documents to increase efficiency and effectiveness– Business Process Re-engineering

• Current business processes designed around paper documents; electronic documents help to reduce cycle time

– Organizational Memory• Both hard data and soft/tacit knowledge stored as documents

providing access to history, design/decision rationale, expertise, best practices, etc.

BenefitsBenefits

• Reduce time to create, review, approve and publish mission critical documents

• Increase accessibility to information; retrieval using business characteristics and full-text searches

• Ensure currency

• Provide access and version control

• Enable enterprise-wide collaboration; reduce email

• Facilitate workflows (sequential and parallel)

• Maintain audit trail

• Increase re-use of components (produce multiple documents from same components)

• Publish electronic & paper documents simultaneously

DM ComponentsDM ComponentsApplications

Attributes and

Content

Create/Capture Store/

Organize

Control/Access/Version

Transmit/RouteReview/

Annotate

Retrieve/Synthesize

Assemble/Publish/Print

Retain/Archive

Document Management Functions

Core Components

Organizational Communication

BPR

RevenueGeneration

OrgMemory

What Firewall Software Does

A firewall is simply a program or hardware device that filters the information coming through the Internet connection into your private network or computer system. If an incoming packet of information is flagged by the filters, it is not allowed through.

How Firewalls Work• Firewalls use one or more of three methods to control traffic flowing in and

out of the network:

• Packet filtering - Packets (small chunks of data) are analyzed against a set of filters. Packets that make it through the filters are sent to the requesting system and all others are discarded.

• Proxy service - Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.

• Stateful inspection - A newer method that doesn't examine the contents of each packet but instead compares certain key parts of the packet to a database of trusted information. Information traveling from inside the firewall to the outside is monitored for specific defining characteristics, then incoming information is compared to these characteristics. If the comparison yields a reasonable match, the information is allowed through. Otherwise it is discarded.

Firewall filters• Firewall Configuration: Firewalls are customizable. This means that you can add or remove

filters based on several conditions. Some of these are:

• IP addresses - A typical IP address looks like this: 216.27.61.137. For example, if a certain IP address outside the company is reading too many files from a server, the firewall can block all traffic to or from that IP address.

• Domain names -. A company might block all access to certain domain names, or allow access only to specific domain names.

• Protocols - The protocol is the pre-defined way that someone who wants to use a service talks with that service. The http in the Web's protocol. Some common protocols that you can set firewall filters for include (next slide):

• Ports - Any server machine makes its services available to the Internet using numberedports, one for each service that is available on the server. For example, if a server machine is running a Web (HTTP) server and an FTP server, the Web server would typically be available on port 80, and the FTP server would be available on port 21. A company might block port 21 access on all machines but one inside the company.

• Specific words and phrases - This can be anything. The firewall will sniff (search through) each packet of information for an exact match of the text listed in the filter.

Types And Sources Of Network Threats

• Denial-of-Service

• Unauthorized Access

• Confidentiality Breaches

• Destructive Behavior

Common Protocols

• IP (Internet Protocol) - the main delivery system for information over the Internet

• TCP (Transmission Control Protocol) - used to break apart and rebuild information that travels over the Internet

• HTTP (Hyper Text Transfer Protocol) - used for Web pages

• FTP (File Transfer Protocol) - used to download and upload files

• SMTP (Simple Mail Transport Protocol) - used to send text-based information (e-mail)

• Telnet - used to perform commands on a remote compute