Mgt 20600: Mgt 20600: IT Management & ApplicationsIT Management & Applications

Networks (cont.)Networks (cont.)DatabasesDatabases

ThursdayThursday

October 13, 2005October 13, 2005

RemindersReminders ReadingReading

– For todayFor today Fundamentals text, Chapter Three, Organizing Data and Information chapterFundamentals text, Chapter Three, Organizing Data and Information chapter

– For the Thursday after breakFor the Thursday after break Fundamentals text, Chapter 6, Information and Decision Support SystemsFundamentals text, Chapter 6, Information and Decision Support Systems

HomeworkHomework– Database/DSS homework will be posted tomorrowDatabase/DSS homework will be posted tomorrow– Due October 28Due October 28th:th: Friday after fall break Friday after fall break

ExamsExams– Medians of 58.6 (Section 3) and 59.5 (Section 4)Medians of 58.6 (Section 3) and 59.5 (Section 4)

Nice work for many of you!Nice work for many of you! If you didn’t do as well as you like, still many hundreds of points to go in the If you didn’t do as well as you like, still many hundreds of points to go in the

coursecourse SuggestionsSuggestions

– Always do reading ahead of time, not just before examAlways do reading ahead of time, not just before exam– Always come to classAlways come to class– Take the homeworks seriously and review them before the examsTake the homeworks seriously and review them before the exams– Come and see me and Christine for help with exam reviewCome and see me and Christine for help with exam review

Next week: Fall break!Next week: Fall break!

Telecommunications and Telecommunications and NetworksNetworks

Elements of a Telecommunications SystemElements of a Telecommunications System

Transmission MediaTransmission Media

Wired Transmission Media TypesWired Transmission Media Types

Wired Media TypesWired Media Types

Wireless Transmission Wireless Transmission Media TypesMedia Types

Radio WavesRadio Waves– BluetoothBluetooth

Short distances onlyShort distances only Relatively slow transmission speedRelatively slow transmission speed Developed for inter-device communicationsDeveloped for inter-device communications

– Wi-FiWi-Fi Standard supports up to 54MbpsStandard supports up to 54Mbps Supports longer distances than bluetoothSupports longer distances than bluetooth

InfraredInfrared– Signals sent as light wavesSignals sent as light waves– Short distanceShort distance– Unobstructed line of sightUnobstructed line of sight

MicrowaveMicrowave– High frequency radio signalHigh frequency radio signal– Capable of high-speed transmissionCapable of high-speed transmission– Unobstructed line of sightUnobstructed line of sight– Susceptible to interferenceSusceptible to interference

CellularCellular

NetworksNetworks

Computer network: Computer network: the the communications media, devices, and communications media, devices, and software needed to connect two or software needed to connect two or more computer systems or devicesmore computer systems or devices

Network nodes:Network nodes: the computers and the computers and devices on the networksdevices on the networks

Network TypesNetwork Types

Personal area network (PAN)Personal area network (PAN) Local area network (LAN)Local area network (LAN) Metropolitan area network (MAN)Metropolitan area network (MAN) Wide area network (WAN)Wide area network (WAN) International networkInternational network

Network TypesNetwork Types

A Typical LANA Typical LAN

Network TypesNetwork Types

A Wide Area NetworkA Wide Area Network

Is the interneta wide areanetwork?

Communications Software and Communications Software and ProtocolsProtocols

Communications software:Communications software: software software that provides a number of important that provides a number of important functions in a network, such as error functions in a network, such as error checking and data securitychecking and data security– Network operating system (NOS) Network operating system (NOS) – Network management softwareNetwork management software– Communications protocol: Communications protocol: a standard set of a standard set of

rules that controls a telecommunications rules that controls a telecommunications connectionconnection

Example, TCP/IP protocol that underlies the InternetExample, TCP/IP protocol that underlies the Internet

The InternetThe Internet

Internet: Internet: a collection of a collection of interconnected networks, all freely interconnected networks, all freely exchanging informationexchanging information

ARPANETARPANET– The ancestor of the InternetThe ancestor of the Internet– A project started by the U.S. Department A project started by the U.S. Department

of Defense (DoD) in 1969of Defense (DoD) in 1969

How the Internet WorksHow the Internet Works Data is passed in chunks called packetsData is passed in chunks called packets

– Internet Protocol (IP)Internet Protocol (IP) Communications standard that enables traffic to be Communications standard that enables traffic to be

routed from one network to another as neededrouted from one network to another as needed Every computer attached to internet has an IP Every computer attached to internet has an IP

addressaddress– Transmission Control Protocol (TCP)Transmission Control Protocol (TCP)

Widely used transport-layer protocol that is used in Widely used transport-layer protocol that is used in combination with IP by most Internet applicationscombination with IP by most Internet applications

In charge of communication session between two In charge of communication session between two computerscomputers

– Uniform Resource Locator (URL)Uniform Resource Locator (URL) Assigned addresses for web servers and the web Assigned addresses for web servers and the web

pages they providepages they provide

How the Internet WorksHow the Internet Works

Routing Messages over the InternetRouting Messages over the Internet

Accessing the InternetAccessing the Internet

Several Ways to Access the InternetSeveral Ways to Access the Internet

Internet Service ProvidersInternet Service Providers

Internet service provider (ISP):Internet service provider (ISP): any company that provides any company that provides individuals or organizations with individuals or organizations with access to the Internetaccess to the Internet– Most charge a monthly feeMost charge a monthly fee– Many ISPs and online services offer Many ISPs and online services offer

broadband Internet access through broadband Internet access through digital subscriber lines (DSLs), cable, or digital subscriber lines (DSLs), cable, or satellite transmissionsatellite transmission

Applications that run over the Applications that run over the InternetInternet

World Wide WebWorld Wide Web Instant MessagingInstant Messaging EmailEmail File Transfer ProtocolFile Transfer Protocol TelnetTelnet All of these areAll of these are

– Software applicationsSoftware applications– Designed for the internetDesigned for the internet– All assume your computer understands TCP/IPAll assume your computer understands TCP/IP

The World Wide WebThe World Wide Web

Hypertext Transfer Protocol Hypertext Transfer Protocol (HTTP): (HTTP): Protocol that web servers Protocol that web servers and browsers use to send requests and browsers use to send requests and informationand information

Hypertext Markup Language Hypertext Markup Language (HTML): (HTML): the standard page the standard page description language for Web pagesdescription language for Web pages

Intranets and ExtranetsIntranets and Extranets

IntranetIntranet– Internal corporate network built using Internal corporate network built using

Internet and World Wide Web standards Internet and World Wide Web standards and productsand products

– Used by employees to gain access to Used by employees to gain access to corporate informationcorporate information

– Slashes the need for paperSlashes the need for paper

Intranets and ExtranetsIntranets and Extranets

ExtranetExtranet– A network based on Web technologies A network based on Web technologies

that links selected resources of a that links selected resources of a company’s intranet with its customers, company’s intranet with its customers, suppliers, or other business partnerssuppliers, or other business partners

Virtual private network (VPN)Virtual private network (VPN)– Secure connection between two points Secure connection between two points

across the Internetacross the Internet– Intranets and extranets often run over Intranets and extranets often run over

VPN’sVPN’s

Internet IssuesInternet Issues

PrivacyPrivacy– Spyware:Spyware: hidden files and information hidden files and information

trackers that install themselves secretly trackers that install themselves secretly when you visit some Internet siteswhen you visit some Internet sites

– Cookie:Cookie: a text file that an Internet a text file that an Internet company can place on the hard disk of a company can place on the hard disk of a computer systemcomputer system

Net IssuesNet Issues

SecuritySecurity– Cryptography:Cryptography: converting a message into a converting a message into a

secret code and changing the encoded message secret code and changing the encoded message back to regular textback to regular text

– Digital signature:Digital signature: encryption technique used encryption technique used to verify the identity of a message sender for to verify the identity of a message sender for processing online financial transactionsprocessing online financial transactions

– Firewall:Firewall: a device that sits between an internal a device that sits between an internal network and the Internet, limiting access into network and the Internet, limiting access into and out of a network based on access policiesand out of a network based on access policies

Net IssuesNet Issues

DatabasesDatabases

A well-designed and well-managed A well-designed and well-managed database is an extremely valuable tool in database is an extremely valuable tool in supporting decision makingsupporting decision making

Databases are key corporate assetsDatabases are key corporate assets Databases are the foundation for Databases are the foundation for

sophisticated analyses that provide sophisticated analyses that provide business intelligencebusiness intelligence– What new products to designWhat new products to design– How to market to particular customer groupsHow to market to particular customer groups– Which customer groups are the most profitableWhich customer groups are the most profitable

Traditional Approach Traditional Approach to Data Managementto Data Management

Traditional approach: separate data files are created for each application

Results in data redundancy (duplication)

Data redundancy conflicts with data integrity

Database Approach Database Approach to Data Managementto Data Management

Database approach: pool of related data is shared by multiple applications

Significant advantages over traditional approach

Advantages of Database ApproachAdvantages of Database Approach

Improved strategic use of dataImproved strategic use of data Reduced data redundancyReduced data redundancy Improved data integrityImproved data integrity Easier modification and updatingEasier modification and updating Data and program independenceData and program independence Better access to data and informationBetter access to data and information Standardization of data accessStandardization of data access A framework for program developmentA framework for program development Better overall protection of the dataBetter overall protection of the data Shared data and information resourcesShared data and information resources

Disadvantages of the Disadvantages of the Database ApproachDatabase Approach

More complexityMore complexity More difficult to recover from a More difficult to recover from a

failurefailure More expensiveMore expensive

DatabasesDatabases

Databases must containDatabases must contain– Accurate informationAccurate information– Right kinds of informationRight kinds of information– Current informationCurrent information– Information from all organizational Information from all organizational

functionsfunctions

Database DataDatabase Data

Data regardingData regarding– Important entitiesImportant entities

CustomersCustomers SuppliersSuppliers TransactionsTransactions

– Each entity will have a number of attributes Each entity will have a number of attributes about which you want to collect and store about which you want to collect and store informationinformation

Customer addressCustomer address Customer phone numberCustomer phone number Customer account numberCustomer account number

Entities, Attributes, KeysEntities, Attributes, Keys

Entity: a generalized class of people, places, or things (objects) for which data is collected, stored, and maintained (Table and records)Attribute: a characteristic of an entity (fields)Data item: a value of an attribute (fields)Key: field(s) that identify a recordPrimary key: field(s) that uniquely identify a record

Hierarchy of DataHierarchy of Data

Field: name, number, or characters that describe an aspect of a business object or activityRecord: a collection of related data fieldsFile: a collection of related recordsDatabase: a collection of integrated and related files

Data Modeling and the Data Modeling and the Relational Database ModelRelational Database Model

When building a database, consider:When building a database, consider:– Content: What data should be collected, Content: What data should be collected,

at what cost?at what cost?– Access:Access: What data should be provided to What data should be provided to

which users, and when?which users, and when?– Logical structure:Logical structure: How should data be How should data be

arranged to make sense to a given user?arranged to make sense to a given user?– Physical organization:Physical organization: Where should Where should

data be physically located?data be physically located?

Data ModelingData Modeling

Building a database requires two Building a database requires two types of designtypes of design– Logical designLogical design

Shows an abstract model of how data should Shows an abstract model of how data should be structured and arranged to meet an be structured and arranged to meet an organization’s information needsorganization’s information needs

– Physical designPhysical designFine-tunes the logical database design for Fine-tunes the logical database design for

performance and cost considerationsperformance and cost considerations

Data ModelingData Modeling

Data model: Data model: a diagram of data a diagram of data entities and their relationshipsentities and their relationships

Entity-relationship (ER) Entity-relationship (ER) diagrams: diagrams: data models that use data models that use basic graphical symbols to show the basic graphical symbols to show the organization of and relationships organization of and relationships between databetween data

Data ModelingData Modeling

An Entity-Relationship (ER) Diagram for a Customer Order DatabaseAn Entity-Relationship (ER) Diagram for a Customer Order Database

The Relational Database ModelThe Relational Database Model

Relational model: Relational model: all data elements are all data elements are placed in two-dimensional tables placed in two-dimensional tables (relations), which are the logical (relations), which are the logical equivalent of filesequivalent of files

In the relational model:In the relational model:– Each table represents a data entityEach table represents a data entity– Each row of a table represents a specific Each row of a table represents a specific

instance of a data entityinstance of a data entity– Columns of the table represent attributesColumns of the table represent attributes

The Relational Database ModelThe Relational Database Model

A Relational Database ModelA Relational Database Model