Title: In the beginning there was darkness, and me also' And I said, Let there be light'
1In the beginning there was darkness, and me
also. And I said, Let there be light.
http//www.imdb.com/title/tt0048960/
- Bomb Number 20 in Dark Star (1974)
2Computer Science 101Lecture 22
http//www.theodora.com/html_colors.html
- Spring Semester 2008
- Friday, March 7
- Week 8/16
- Albert H. Carlson
3Announcements
- Due March 7 Midterm Essay
- The second set of layouts are due on March 14
- Bring your FLASH drive to lab
- Bring your Castro Book on HTML to lab. Also,
study the assigned reading to this point so you
are familiar with it. - Next week is Spring Break
4Linking in HTML
- E-mail (getting the e-mail tool to e-mail back to
you) - ltA HREF"mailtocarl3007_at_uidaho.edu"gtClick Here
To Write Melt/Agt - To other Pages
- ltA HREF"http//www.htmlgoodies.com"gtClick Here
For HTMLlt/Agt - To spots on the same Page
- ltA HREFtop"gtReturn to toplt/Agt
- ltA NAME"purchasing"gt
- Note that the anchor does NOT contain a
5Using Other Pages as Examples
- One of the best ways to see how things are done
is to see what other people did on their pages - Go to the Browser toolbar
- Select View
- Then select Source from the pull down menu
6Good Tutorials
- Try some of these sites for examples of the kinds
of things that can be done, and how to do them - www.htmlgoodies.com
- http//www.hitmill.com/html/primer.html
- http//www.fiu.edu/learnhtml.html
7The Example
81 row, 4 cols
The Page
TITLE
3 rows, 1 col
Marquee
TEXT
TEXT
PICTURE
L I N K S (NAV MENU)
5 rows, 1 col
TEXT
3 rows, 1 col
PICTURE
TEXT
PICTURE
PICTURE
3 rows, 1 col
TEXT
TEXT
PICTURE
Contact Info
CONTACT INFO
9The Example
- Lets start with the title block
- We are going to add a couple of things in the
title - I want a BIG Title and a marquee that comes
across in tecnicolor
10The Example
- Start with the heading
- Use the H1 size
- Next we add the marquee what do we want it to
say? - Once again, notice that we are embedding commands
for the marquee
11The Example
- So far we have put in the pictures
- Now we need to fill in the rest of the details
- Lets start with the title block
- We are going to add a couple of things in the
title - I want a BIG Title and a marquee that comes
across in technicolor
12The Example
- Now, lets add some links to the bottom of the
page - This is the contact info that describes who and
what I am - We will link to
- U of I (of course) www.uidaho.edu
- My CS instructor page www2.cs.uidaho.edu/acarlson
- SAR www.sar.org
13Finishing the Example
- Now that we have a first page, it is time to link
the other pages together in order to form the
total package - Lets make three other pages that we will link
into - Practice1.html
- Practice2.html
- Practice3.html
14End of the Example
- Where we want to go now is to create three very
simple pages for one reason - Show linking the pages between each other
- A page that you link to that does not link to
other pages is called a sink page - Each of these will have a different background
color and link to each of the other pages, as
well as the index page
15Other HTML Tags - Lists
- ul vs ol
- ol uses numbers
- ul uses one of
- Disc
- Square
- Circle
- Both use ltligt to put an item on the list
- Be sure to remember the header!
16Linking in HTML
- E-mail (getting the e-mail tool to e-mail back to
you) - ltA HREF"mailtocarl3007_at_uidaho.edu"gtClick Here
To Write Melt/Agt - To other Pages
- ltA HREF"http//www.htmlgoodies.com"gtClick Here
For HTMLlt/Agt - To spots on the same Page
- ltA HREFtop"gtReturn to toplt/Agt
- ltA NAME"purchasing"gt
- Note that the anchor does NOT contain a
17Cascading Style Sheets
- An addition to HTML
- Found only in the Head of the HTML page
- Have the form tag property value
- H1 color FF0000
- This command makes all text red when it a H1
command is processed - Can have more than one property for a tag
- Tell the browser what to do whenever a tag is
found and processed.
18CSS
- Almost all tags can be done this way
- Some tags CANNOT be modified
- Title
- Meta tags
- HTML
- Head
- The point of CSS is that they can control a great
deal of things without having to redefine it each
and every time
19CSS
- An example working on the background
- First, what is required to get a CSS started?
- ltstyle typetext/cssgt
- lt/stylegt
- This command tells the browser that a cascading
style sheet is being used and defined
20CSS
- ltstyle type"text/css"gt
- body
- background-colorffff00
- background-imageurl(tinafish.jpg)
- background-repeat no-repeat
- color000000
- font-family 'times new roman', arial,
sans-serif - lt/stylegt
21CSS
- One of the really neat things is that you can use
both a background color and picture. - Here we are going to use the
- Background-color
- Background-image
- Background-position
22CSS
- Lets go and do an example, using a Cascading
Style sheet - There are OTHER things you can do with a CSS
- The Class
- Starts with a . and has a name
- Ex .red
- Can be used with either a command or a div
23CSS Classes
- Examples
- lth1 class redgt Title Blocklt/h1gt
- ltdiv class redgt
-
- lt/divgt
- Everything identified as using the class will
take the attributes and properties of the class
red
24CSS IDs
- Similar to the Class is the ID
- Uses a in the definition
- Can only be used ONE TIME in a page. Using it
more than once will result in errors - Example
- red h1colorred
- ltdiv id redgt
- .
- lt/divgt
25CSS
- Tutorials
- http//www.blooberry.com/indexdot/css/propindex/al
l.htm - http//www.devx.com/projectcool/Article/19813
- http//www.htmldog.com/reference/cssproperties/
- www.w3.org
- www.maxdesign.com.au
26Now That We Have a Page
- Well, Now you know how to create a web page that
can be put up on the internet. - How, exactly, are we going to get to that page
that is on a computer SOMEWHERE in the world? - The internet is the key and now we go on to
discuss networks, and the internet, in general
27Publishing Your Page
- Here at the U of I, we have reserved space for
each student - Each student has a public_html directory in their
H\ drive - This is common on Unix/Linix systems. All pages
MUST be in this directory. It allows the system
to look in a predefined place - Put all of your files here for your pages
28Ways to Get the Page Up
- Copy files to disc or thumb drive
- Go to a Compter Lab on Campus, copy from your
disc/drive to H\public_html - Or, use FTP and copy the programs across to the
same directory - Remember to copy ALL files, including pictures
and supporting files (music, etc) into that same
directory
29Page Problems
- The most common problems are
- Absolute vs. Relative Addressing
- Absolute addressing is in the form of
c\web\page2.html - Note it specifies the EXACT path to the page
- If the path changes AT ALL, this will be a broken
link - Relative addressing is of the form ..\page2.html
- It is relative to the PAGE BEING DISPLAYED
30Page Problems
- Next is BROKEN LINKS
- A link is broken if it cannot find the
file/picture/whatever it is looking for - Pictures are most often broken
- Remember to store the pictures along with the
file - Misspelling is also a favorite reason for broken
links
31Other Page Problems
- Bad color combinations
- Busy backgrounds
- Not watching the text color and making it fade,
disappear, or go psychedelic - Not linking between pages (a sink page)
- Not updating regularly (pages get boring)
- Incorrect or misleading meta tags
- No meta tags
32New Subject
- Now we have to discuss a new subject the
environment where the software runs
The Operating System (OS)
33Operating Systems
- System software is software that controls a
computer - Officially, the operating system (OS) is a set of
programs that coordinates all of the hardware
activities in a computer - It is transparent to the user. That is, you do
not have to actually direct itself - It is actually put on the hard disk
34Operating Systems
- The basic operating systems are
- Windows (pick your flavor IBM type)
- Mac OS (Apple)
- UNIX
- Linux
- History of OSs http//www.levenez.com/unix/histor
y.html - Windows is built on MS DOS
- Application Programs are written on the OS
35OS
- Each size machine has a different type of OS
- Even the same size machines can choose from a
number of OSs. Mac has its own in several
versions, so does Windows - Among the functions we have for an OS is to start
up a computer - Warm
- Cold
36OS Types
- Mainframe
- Server
- Laptop/Desktop
- Mobile
- Palm
- Custom
37Networks
- Need to get information from one computer to
another - Used to do it by typing it in one computer at a
time - Sneakernet
- Wanted to do this using existing networks
- Power
- Phone
38Modems
- Needed a way to translate data from computer to
electronic/voice signal - Uses this as a translator
- Then it has to translate back to electronic
signal again - Started at 110 baud
- Now can go upwards of GB/s
39More Networks
- They also have some sort of control
- This is called a protocol
- Protocols are basically instructions about how
something should work - There are various levels of protocols
http//www.freesoft.org/CIE/Topics/15.htm
40Network Topics
- Nodes
- Computer
- Gateway
- Hub
- Switch
- Router
- Other types of electronics connected to the
network
41Networks
- Types of Networks
- Bus Type (ethernet)
- Easy
- Cheap
- Multi-Drop
- Easy to break
42Another Network
- Ring
- Longer to get around
- Each link is point to point between nodes
- Harder to break
- More expensive
43The Star
- Star
- The Good
- Predictable Timing
- Faster than Ring
- Cut one wire, most
- still work
- The Bad
- More expensive
- Central node failure
44Yet Another
- Star Wired Ring
- Advantages of both star and ring
- Pretty fast
- Pretty reliable
45The Internet
- A relatively new invention
- Really is a NETWORK of NETWORKS Note that I
said this several times - Gateways can be a hub or a switch
- Switches have brains, hubs do not
46The Internet
- The internet is a NETWORK OF NETWORKS
- Most networks have nodes, media, and at least one
node that acts as a gateway - Gateways connect from one network to another
47History of the Internet
- How has the Internet grown?
48History of the Internet
- No oneccit is a public, cooperative,
andindependent network - Several organizations set standards
- Who controls the Internet?
49How the Internet Works
- Text version of Internet protocol (IP) address
- Number that uniquely identifies each computer or
device connected to Internet
50The World Wide Web
- Program that allows you to view Web pages
51The World Wide Web
Unique address for a Web page A web server
delivers the Web page to your computer
52TCP/IP Again
- It has an address called the IP address in
order to get packets to the right place - Addresses are of the form
- XXX.XXX.XXX.XXX
- XXX can be any number from 0 255
- The address is normally assigned by the network
you are on - Dynamic address allocation is called DHCP
53The World Wide Web
- Built-in connection to another related Web page
location
- What is a hyperlink (link)?
- Item found elsewhere on same Web page
- Different Web page at same Web site
- Web page at a different Web site
543. DNS Returns IP Address
2. Request for IP Address from DNS Server
1. Put URL into Browser
- Form Request for
- page on PC
5. Send Request to Web Site Server
6. Server Loads Page and sends it back to you
7. Browser loads page
8. View Page
55OK, Get Me www.x...
Who has www.x...
Me! 4ms
Ok, I Choose
Me! 4.5ms
Me! 8ms
www.x...
56The World Wide Web
- Program used to find Web sites and Web pages by
entering words or phrases called search text
57Good Search Engines
- Google
- Ask
- Dogpile
- CiteSeer (normally for science research)
- Lexis Nexis (LAS research)
- Google Scholar
58Ive Been Searching So Long
- Nesting using ()
- Binary Searches (Really more of a logical search)
- Uses the Binary Operators
- AND (Cat AND Siamese)
- OR (Cat OR Siamese)
- NOT (Cat NOT Siamese)
- Uses them in combination with key words
59The World Wide Web
- What graphics formats are used on the Web?
BMP
JPEG(pronounced JAY-peg)
PNG(pronounced ping)
GIF(pronounced JIFF)
PCX
TIFF
60The World Wide Web
- Appearance of motion created bydisplaying a
series of still imagesin sequence
61Not What it Seems
- Not all web information is created equal
- Authors can say anything they want, are normally
seen as anonymous, and use that privilege to say
what they want - What they say is not always true
- It is up to YOU to determine the validity of the
information you find
62Evaluating Internet Info
- Who is the author? Is the author an authority?
Credentials? Did the author identify him/herself
on the page? If it is a company, are they
respectable? - Does the author cite sources? If so, do they
appear to be reliable and from respected and
recognized publications?
63- Who is paying for the page? Do they have some
reason for bias? - Does the material SEEM one sided or biased?
- Does the page seem like it is set up to ARGUE, or
is it even toned? - Would the author benefit from selling something
on the page?
64- Does the information seem accurate? Is it
specific, does it make sweeping generalizations?
Are there lots of simple errors on the page? - Is the page up to date? When was the last update?
65Spam
- Spam is stuff you do not want to receive
- Comes mostly from Mass Mailers
- Usually Selling Stuff (Some come from political
parties) - Stopped by a Spam Filter
- Can be reported to your ISP
- Big fights right now about legality vs. free
speech
66But Does it Pay?
- The Web is fun, it gives us a lot of information,
but why is it still there? - The obvious answer is because, it makes money.
- So what is it that we call making money on the
Web? - E-commerce
67E-Commerce
- Been going on since the beginning of the web
- Roughly split between businesses doing business
for businesses and those selling right to the
customer - B2B is the abbreviation for business to
business
68- Businesses may have only an electronic presence
- Amazon
- Thinkgeek.com
- Others have BOTH traditional stores and sell on
the web. They are called click and brick - Traditional stores are called brick and mortar
69B2Bs
- B2Bs exist on a value added network or VAN
- Each business has a point of presence, or PoP
on the VAN - Information is sent back and forth using
Electronic Data Interchange, or EDi
70The Good, the Bad and the
- Electronic business is easy and convenient
- You can compare lots of sites and get the best
prices - There are pictures and pricing is usually easy to
find - However, .
71The Bad
- You have to know what you are looking for in
order to find it - The quality of the experience depends on the
interface and the programmer who made it - You never know who is listening in
- People tend to keep records of what you buy
72Common E-Businesses
- Online Banking
- Booking travel and travel related items cars,
hotels, tickets - Books
- Amazon
- Clothing
- Camera and electronics
- Dell
73Privacy and Security
- Computer Security Risk
- Anything that could cause loss of, or damage to
- Hardware
- Software
- Information
- Data
- Processing capabilities
74People in Security
- Hacker
- Used to be complementary
- Anyone who accesses a computer or network
illegally - Often claim to be making the system better by
exposing its problems - Cracker
- Hacker who is going to destroy or do damage
75People in Security
- Script Kiddie
- A cracker using other peoples software to do
damage - Do not have the talent of a cracker or hacker
- Generally looked down upon by the pros
- Corporate Spy
- Hired to break into some other companys records
in order to get an advantage over the company
being spied on
76People in Security
- The most dangerous of all hackers
- the employee
- Typically has one of a few motives
- Financial Gain
- Revenge
- Exploit a weakness just to see if they can
- Capable of doing GREAT harm to a system
77People in Security
- Cyberextortionist
- Threatens to damage, or damages, systems if not
paid - Sometimes uses the DOS or DDOS
- Cyberterrorist
- Pretty much the same thing as a
cyberextortionist, but does damage for political
reasons
78Types of Attacks
- System Failure
- Information Theft
- Unauthorized use and access
- Hardware Theft
- Software Theft (illegal copying)
- Internet and network attacks
79Internet and Network Attacks
- There are lots of possible attacks
- The internet is especially vulnerable because it
is so open - Sniffing
- Monitoring the traffic going by without doing
anything to the data - Just plain a type of listening
80Internet and Network Attacks
- Spoofing
- Pretending you are another, valid, user
- May involve conversations and answering data
- Often done with IP addressing
- Man in the Middle
- Lets say there are two people who want to talk
- We will call them A and B
81Internet and Network Attacks
- We do NOT want to keep A from talking to B
- Rather, we want in on the conversation
82Internet and Network Attacks
- What we do, as C is to start conversations with
BOTH A and B - We spoof that we are B when we talk to A
- Similarly, we spoof that we are A when we talk to
B
83Internet and Network Attacks
- The idea is to get information sent to us that A
wants sent to B, or vice versa, that they would
normally NOT want us to see - Malware
- Then we have the normal bad stuff we have talked
about before - Trojan Horses with payload
- Viruses
- Worms
- Etc.
84Attacks
- Just remember that
- Viruses affect ALL known OSs
- About 81,000 are presently known
- About 6 are added every DAY
- If you are on the network, you are vulnerable
- If you are getting any files that you do not
PERSONALLY write, you are vulnerable - Commercial software is also vulnerable
85Attacks
- The Denial of Service (DOS)
- The Distributed DOS (DDOS)
- Back Doors
- Bacterium and Rabbits
- Zombies
86Safeguards
- Dont turn it off unless you absolutely have to
- Virus checker
- Dont start the computer with removable media
in the computer - E-mails
- First dont take e-mails from people you do not
know - Dont open attachments if you do not know the
sender
87Safeguards
- Disable macros
- Watch out for the virus hoax
- A hoax is a message telling you about a virus
- Usually warns of dire consequences if ignored
- Have some weird instructions as to what to do
to avoid the virus - Can have instructions that cause damage if you do
them - Is a form of social engineering
- Always check with McAfee or Symantec first
88Safeguards
- Intrusion Detections Systems (IDS)
- Takes two different tacts
- Looks for out of the ordinary activities
- Looks for specific bad activities
- There are problems with this type of software
- You cannot detect someone until they are already
inside your network and computer - You have to know what you are looking for in
order to find it
89Safeguards
- Access Control
- You must GIVE permission for anyone to use your
computer or network - Usually takes the form of User IDs and passwords
- Passwords are only as good as they are designed
to be - The longer and more diverse, the better
90Time to Crack a Password
91Safeguards
- Dont turn it off unless you absolutely have to
- Virus checker
- Dont start the computer with removable media
in the computer - E-mails
- First dont take e-mails from people you do not
know - Dont open attachments if you do not know the
sender
92Safeguards
- Disable macros
- Watch out for the virus hoax
- A hoax is a message telling you about a virus
- Usually warns of dire consequences if ignored
- Have some weird instructions as to what to do
to avoid the virus - Can have instructions that cause damage if you do
them - Is a form of social engineering
- Always check with McAfee or Symantec first
93Safeguards
- Access Control
- You must GIVE permission for anyone to use your
computer or network - Usually takes the form of User IDs and passwords
- Passwords are only as good as they are designed
to be - The longer and more diverse, the better
94Information Theft
- Usually applies to things like credit cards and
trade secrets - Often, passwords and IDs protect the information
- Sometimes encryption of the data is also used
- Encryption obscures the data by changing it
according to some function
95Encryption
- Substitution
- Changing one character for another
- Transposition
- Change the order of the letters
- Stream
- One character gets part of a key and the key
either repeats or changes based on the data in
the message
96Encryption
- Polymorphic
- Changes keys and/or encryption types over time
- Good keys are published and analyzed
- Do not trust security by obscurity
- Other methods
- Digital signature
- Trusted third party
97Encryption
- Common Encryption Algorithms
- Substitution Cipher
- PGP
- DES
- Blowfish
- Twofish
- WEP
- One Time Pad
98Encryption
- Block
- Take part of a message, do the encryption, then
move on to the next block - Key Encryption
- Uses a set of keys to encrypt and decrypt
- PKE/PKI
- Depends on a public and a private key
- Encrypt with public key, decrypt with private
99Encryption
- Polymorphic
- Changes keys and/or encryption types over time
- Good keys are published and analyzed
- Do not trust security by obscurity
- Other methods
- Digital signature
- Trusted third party
100Encryption
- All encryption methods become insecure after a
certain number of symbols are seen - The trick is to use the right method for the
right application - Each cipher can be analyzed to find the unicity
distance - Every cipher CAN be broken, except the OTP
101Information Theft
- Usually applies to things like credit cards and
trade secrets - Often, passwords and IDs protect the information
- Sometimes encryption of the data is also used
- Encryption obscures the data by changing it
according to some function
102System Failures
- This is another method of damaging hardware
- It is basically interrupting power to the unit
- To prevent, use
- Serge protectors
- Battery
- UPS
103Data Loss
- Loss of data often creates problems
- Can be created many ways
- One real way to avoid it
- Backup your data
- CD
- Tapes
- Off site storage
- Never keep all of your backups in one place!
104Phishing
- Weird name for a bad activity
- This is a form of social engineering
- It is an attempt to get data from you
- Asks you to return the information that they want
and need - Remember that legitimate people do not ask you to
submit information without a good reason.
105Keeping Your Info Safe
- Only fill out what is necessary
- Only give access permission when required
- Dont write phone number on checks
- Dont allow merchants to write SSN, DL, or other
data on your checks - Avoid buyers clubs or store discount cards
106Keeping Your Data Safe
- Request, in writing to be removed from mailing
lists or calling lists - Get rid of cookies
- Clear history after browsing the web
- Use a free e-mail account for work with
merchants. Maintain a private account for your
friends and family - Check credit reports annually
107Keeping Your Data Safe
- Turn off file and printer sharing
- Install a firewall
- Never, Ever, respond to spam
- Use available e-mail filtering
- Surf the web from anonymous web sites built for
that purpose
108Is the Computer Safe?
- If you cant turn on a computer, is your
information safe? - The answer is NO
- Computer Forensics
- Used by Law Enforcement and Government
- Uses quite a few very complicated processes
109Monitoring
- Employers can monitor your computer use
- Most often, done by using a net nanny
- Almost all companies have a policy in place that
allows this and specifies limits - Information CANNOT be made public
- Making information about monitoring public can
result in law suits
110Monitoring
- Sites that are usually NOT allowed to be visited
- Porn (Sexual Harassment Issues)
- Online Games (Should be working!)
- Religious sites
- Weapons sites (Basic self preservation)
- Sites with violent themes
- Political sites
111Data bases
- Must start with a review of why we put together
data bases - Data bases are good for keeping RELATED pieces of
information together - Some data is related by nature
- Examples
- Name
- Address
- SSN
112Why the DB?
- Information sometimes is so linked that it must
be used together - You do not always need ALL of the information at
the same time - Sometimes you need specific parts of the
information - All of the data must be managed
- This gives rise to the DBMS
113DBMS
- Data is stored in a DBMS
- Data is organized by something unique about the
thing being identified - This item is called the key
- The key links to all of the other information in
the collection of information - By locating the key and following the links, we
can retrieve the rest of the data
114Data
- Most companies and organizations have recognized
that data is one of their most valuable assets - Companies without data recognize that they are
out of business - But, data is only as good as the information that
it represents and the source it comes from
115Data
- Companies also recognize that data is only as
good as the person that puts it in - GIGO
- Information must be analyzed before it can be
evaluated - Information has certain properties that have to
be considered
116Information
- Must be
- Accurate (error free)
- Verifiable (can be proven to be true or false)
- Age (most information losses value with time)
- Organized (information needs to be in a useful
order) - Accessible (information you cant get to will not
do you any good)
117More Information
- Useful (Meaningful to the person who has to use
it) - Cost effective (the information that you are
going to use has to generate more value for you
than it takes to gather the information) - Data also has a hierarchy
118Data (Some More)
- This is a lot like using an object in a class
- Each piece of information has attributes
- Each piece of information is placed into a
field - Fields are composed of one, or more, characters
and are the smallest amount of data that a user
can access - Each field has a field name
119Field Types
- Common Field Types include
- Text
- Numeric
- Autonumber
- Currency
- Date
- Memo (lots of text)
- Yes/No
- Hyperlink
- Object
120Data
- A group of related fields constitutes a record
- A group of related records is called a data
file - A data base must be able to
- Add records
- Delete records
- Edit records
121Data
- A data base consists of
- A data file (sometimes called a table)
- Forms (a way to get data into the data base)
- Reports (an organized way to get data out of the
data base) - Generally data is only changed for two reasons
- Correct bad data
- Update records
122Data Integrity
- When data is changed, or added, to a record, the
DBMS checks the data - Validity (data is of the right type)
- Numeric Check
- Alphabetic Check
- Range Check (values are in the proper range)
- Consistency Check (dates are in order)
- Completeness Check (field is filled)
- Check Digit(s)
123File Systems vs DBMS
- The alternative to a DBMS is a File System
- File Systems are a group of files kept by each
department in a company - Each department records are NOT linked
- Each file has to have the data recorded
separately - Updating one does NOT update the others
- Wastes time, effort, and data is isolated
124The DBMS Solution
- Uses a CENTRAL file that is access by ALL users
- Data is NOT duplicated
- Data is the SAME for all users
- Data is easier to access and share
- Data is only entered one time
- Since it is only one program, multiple programs
do not have to be developed, tested, and
maintained
125The DBMS Solution
- Minuses
- The DBMS is typically more complex than a simple
file system - Often, specially trained people are required to
run and maintain the DBMS - DBMSs require bigger computers with more memory
- Data is more vulnerable, only one copy of the
data exists
126Major DB Types
- Relational
- Uses SQL and Tables and 2 dimensions
- Object oriented
- Uses Object Query Language with objects
- Runs faster, stores more
- Not supported by all DB packages
- Multidimensional
- Stores data in separate dimensions
- No standard query language
127The Data Dictionary
- People need to know what kind of data is used on
the data base - For this, they have a definition of what goes in
the DB - This is called the data dictionary
- Consists of the field name, definition of what
goes in the field, and what values may be used in
the field
128Using the Data Base
- Getting data out of the DB requires, basically,
asking for the data - This action is called a query
- Queries have their own protocol. It is called a
query language - Reports and output are programmed in a query
language - Remember to backup often!
129Using the DBMS
- Security
- Some Users should NOT be allowed to get into the
Data Base and change things - Each user has an authorization
- Several authorization levels are available
- Queries
- Most queries use a language known as SQL
- Structured Query Language
130Major DB Types
- Relational
- Uses SQL and Tables and 2 dimensions
- Object oriented
- Uses Object Query Language with objects
- Runs faster, stores more
- Not supported by all DB packages
- Multidimensional
- Stores data in separate dimensions
- No standard query language
131Some Fun Terms
- Data Mart
- A large multidimensional data base used by a
department or group to analyze and make decisions - Data Warehouse
- Same as a data mart, but on a company wide scale
- Web Data Base
- A data base that can be web accessed
132DB Design
- As always, determine what you want
- Design the DB (sound familiar, like the life
cycle methods?) - Figure out the tables
- Each table should contain data on ONE subject
- Design the records and fields for each table (Top
Down Design)
133DB Design
- Be sure you have unique keys
- Make fields for DISTINCT functions (name, title,
etc.) - Do NOT store data that can be derived from other
data - Make sure you have enough space in the field
- Set default values when and where you can
- Determine the relationship between tables
134DB Professionals
- Database Analyst (DA)
- Decides how the data will be used and put
together - Decides on access rights
- Mainly a designer
- Database Administrator (DBA)
- Does the actual implementation
- Often the DA and DBA are the same person
135Being a Software Professional
- The Good
- Interesting Problems to Solve
- Good Money
- Good Working Conditions
- Respect
- Travel
- Great Toys
- Newest Technology
136Being a Software Professional
- The Bad
- Schooling never stops
- Long hours
- Deadlines
- Living up to expectations
- The lab
- The boss and marketing
- The reputation
137And Me?
- This is VERY hard work
- The hard part is mental, not physical
- I live months for the 5 minutes that I demo
- Almost no one knows what you have done it is an
inner satisfaction - I would not trade it for anything
138What have we learned?
- Parts of the computer
- Roughly what a computer does
- Hardware and software
- Security, privacy, etc.
- MS Office
- Languages and HTML
- Programming
139More Stuff
- OSs
- Networks
- Internet, protocols, and operation
- How to maintain and customize your computer
- Data bases
- E-commerce
- And how to program a bit
140Questions?