BMIS 289: Spring 2001

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BMIS 289 Spring 2001

• ASP FundamentalsJanuary 29, 2001

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Program 1 Algorithm

• Input the stock transaction details
• HTML Form
• Get data from input form
• Calculate results of transaction
• TotalCost PurchasePrice n
• Return TotalCost (ClosingPrice n)
• (where n is the number of shares bought)
• Output the results
• Echo form inputs
• Output TotalCost and Return

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Program 1 - Code

• HTML Input Form
• Input.htm
• Process.asp
• Program header comment
• Declare and initialize variables
• Calculate the total cost of the purchase and its
  return
• Output

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Virtual Directories

• A physical directory is an actual path on a
  servers hard drive
• C\inetpub\wwwroot\mywebsite
• A virtual directory points to a physical
  directory
• http//www.webserver.com/mywebsite ?
  C\inetpub\wwwroot\mywebsite
• So when a browser sends a request to the web
  server for http//www.webserver.com/mywebsite/page
  .asp the virtual directory we setup knows to look
  in c\inetpub\wwwroot\mywebsite for the file
  page.asp

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Setting Up A Virtual Directory With Personal Web
Server

• Launch Personal Web Server
• Launch the Personal Web Manager
• Usually this is an icon in the system tray of the
  taskbar (lower right-hand corner).
• Select Advanced and then click Add
• Browse to the directory you want this virtual
  directory to point to, then enter an Alias for
  it.
• Read and Scripts permission is usually adequate.

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How The Web Works

• The web is built on the client-server
  relationship
• Server hosts software, data, processes,
  information, etc.
• Clients access these servers to get at this
  stuff.
• All these interconnected systems allow universal
  access.
• The web also operates under several protocols
  (rules for communicating), the most important
  ones being TCP/IP and HTTP

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TCP/IP

• TCP Transmission Control Protocol
• Responsible for packaging data up before its
  sent over a network and then unpacking it and
  reassembling it properly on the receiving end.
• IP Internet Protocol
• Responsible for getting the data to where it
  needs to go (i.e., how to get from A to B).

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HTTP

• Hypertext Transfer Protocol
• An application protocol that is a specific type
  of Internet protocol. It focuses on the
  addressing and delivery of files (text, sound,
  video, etc).
• HTTP Request
• Message going from Browser ? Server
• HTTP Response
• Message going from Server ? Browser

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HTTP Request (pg. 60)

• Request Line
• Details about the request itself.
• HTTP Header
• Misc. meta information (usually about the client
  making the request).
• HTTP Body
• Any data the client is sending to the server
  (like form input fields).

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HTTP Request Request Line

• How much information the client needs and how
  much information is being sent.
• Method Types
• GET obtain data at a particular URL. Any input
  the user entered is appended to the URL.
• POST Data will be sent to the server as part of
  the HTTP request.

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HTTP Request HTTP Header

• The HTTP Header contains details about the client
  and other general configuration information.
• Types of information found in HTTP Header
• General info about client or server.
• Entity information about data being sent between
  client and server.
• Request information about client configuration
  and what kind of documents it accepts.

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HTTP Request HTTP Body

• In an HTTP Request the HTTP Body section is
  usually empty, unless we used the POST method
  when sending our HTTP Request.

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HTTP Response Response Line

• Contains only two bits of information
• HTTP version number
• Request code that indicates success or failure of
  the request.
• HTTP Error 404 is one of the most common HTTP
  Request codes you will run into on the Internet.
• The 404 error indicates that the document you
  were looking for was not located where the
  request thought it was.

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HTTP Response HTTP Header

• Similar to the Request HTTP Header
• Information falls into three types
• General Information about client or server.
• Entity information about data being sent between
  client and server.
• Response information about the server

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HTTP Response HTTP Body

• If the Request is successful then the resulting
  HTML code is sent back in the HTTP Body.

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Script Languages

• The current version of ASP is not a typical
  compiled programming language.
• It is a script language.
• Code written in a script language is processed
  dynamically by a script engine which interprets
  the code and outputs the results.
• The default ASP script language is VBScript,
  though other script languages like JScript can be
  used.

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Server-Side Client-Side Script

• Server-Side Script
• Code is executed on the server.
• Since we can control the server that processes
  the script we know that all browsers will get the
  same results back.
• Can be slower to execute than client-side script.
• Client-Side Script
• Code is executed on the client browser.
• Usually is faster than server-side.
• Different browsers produce different results with
  same code (Browser Dependent).

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Scripting Examples

• Server-side Inline lt gt
• Script engine writes the results of the code
  directly into the HTML stream at the positions we
  indicate.
• Server-side ltscript runatservergt
• Script engine appends results to the end of the
  HTML stream.
• Client-side - ltscript runatclientgt
• ASP engine ignores this code and will let the
  browser process it.
• JavaScript is the most popular client-side
  scripting language.
• Order of execution examples on pg. 80 in your
  book.

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Objects Components

• Objects are packages of related code that provide
  certain information (properties) and
  functionality (methods) to programmers
• Components are collections of certain objects.
• ASP has several pre-built (intrinsic) objects and
  components for programmers to use.
• Programmers could also write their own objects
  and components to supplement ASP.
• These are often known as custom or third
  party components.

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Intrinsic ASP Objects

• Request
• Used to deal with the requests users make for web
  pages. This request could be anything from an
  HTML form to a simple URL.
• Example Request.Form(FormField)
• Response
• Deals with web servers response back to the
  client.
• Example Response.Write Hello web browser!
• Server
• Functions only the web server can perform, like
  setting the amount of time a user can be idle.

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Intrinsic ASP Objects Cont.

• Application
• A web application is considered a collection of
  related ASP pages and other files. The
  application object can be used to manipulate
  these web applications.
• Session
• Every time an individual user arrives at our web
  site the web server generates a unique session to
  reference them. We use the session object to
  manipulate and retrieve information related to
  that session.

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Some Intrinsic ASP Components

• Ad Rotator
• Manage banner advertisements
• Browser Capabilities
• Determine what kind of browser a user visiting
  the site is using.
• Microsoft Data Access Components (MDAC)
• Set of objects for accessing and manipulating
  databases.

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Quick Review Of The Basics

• Input
• Create HTML form.
• Send data to an asp page for processing.
• Process
• Get the data using Request.Form and store the
  values in variables.
• Manipulate data in variables (perform arithmetic,
  sort data, save data in offline storage).
• Output
• Write the results of the process to the HTTP Body
  (as HTML) using Response.Write

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Generating HTML

• So far we have seen how we can output values a
  user has entered into a form, using
  Response.Write
• But Response.Write doesnt have to output only
  what the user has entered and the values of any
  processes performed On that input.
• We can use ASP to generate HTML code itself (code
  generates code).

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Why Generate HTML?

• Aesthetic reasons primarily.
• HTML is a presentation language, so using ASP to
  dynamically generate HTML code can make the
  resulting page look more pleasing to the eye.
• Using HTML elements like tables to format output
  from a database query can make the information
  easier to interpret and read.
• Example (code on our class web site)

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HTML Table

• Useful for presenting information in a clean,
  logical manner.
• Good way to format the layout of a page.
• Base tag lttablegt
• Row tag lttrgt
• Cell tag lttdgt

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ltTABLEgt Attributes

• Width pixel or value (percentage of the
  browser screen)
• Border pixel value
• Bgcolor red, blue, etc or rgb values
  (FFFFFF white)
• Cellpadding pixel value, the amount of padding
  space around text in individual cells.
• Cellspacing pixel value, the amount of spacing
  between individual cells.

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ltTRgt Attributes

• Bgcolor color name or rgb value.
• Align CENTERLEFTRIGHT how text in the rows
  cells is horizontally aligned.
• Valign TOPMIDDLEBOTTOMBASELINE how text in
  the rows cell is aligned vertically.

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ltTDgt Attributes

• Bgcolor color name or rgb value
• Width pixel value or
• Height pixel value
• Valign, Align same as ltTRgt tag.
• Colspan number of columns above or below a cell
  should overlap.
• Rowspan number of rows the cell should overlap.

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HTML Table Example
lttable border1gt lttrgt lttd colspan2gtcell 1,
row 1lt/tdgt lttd rowspan2gtcell 2, row 1lt/tdgt
lt/trgt lttrgt lttdgtcell 1, row 2lt/tdgt
lttdgtcell 2, row 2lt/tdgt lt/trgtlt/tablegt
Renders As
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Variables

• A variable is simply a slice of computer memory
  that a programmer names in order to reference in
  their code later.
• ExampleDim myVarmyVar 5

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Data Types

• A data type indicates what kind of information a
  variable is holding, such as an integer, a
  floating point number, a text string, or a single
  character.
• VBScript does not have native data types. By
  default all variables in VBScript are of the
  Variant data type.
• A variant can hold any type of data. VBScript
  automatically determines what type of data is
  located in a variable of the variant data type.
• However, we can also explicitly tell VBScript
  what data type a particularly variable is using
  conversion (in case the Script Engine guesses
  wrong when interpreting it).

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Numeric Types

• Integer whole numbers
• 32,767 to 32,768
• Byte small range of integers
• 0-255
• Useful for basic arithmetic
• Long a larger integer
• 2,147,483,647 to 2,147,483,648
• Double very accurate floating point precision
• Currency
• 922,337,203,685,477.5807 to -922,337,203,685,477.5
  808

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Other Types

• String holds text
• Examples Hello, 123, July 4, 1776,
  12.32
• Date holds dates and times
• Boolean only two possible values (TRUEFALSE)
• Null literally nothing. A zero or an empty
  string () are not null, those are something. A
  null is nothing.
• Empty variables that have yet to be assigned are
  called empty, or uninitialized.

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Data Type Conversion Functions

• Example
• Dim PricePerSharePricePerShare
  Request.Form(PPS)PricePerShare
  Ccur(PricePerShare)
• Data Type Conversion Functions
• Currency Ccur()
• Integer Cint()
• Double Cdbl
• String Cstr()
• Others listed on pg. 145

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Declaring Variables

• Declaring
• Dim VariableName
• lt Option Explicit gt
• By default ASP allows us to declare variables
  implicitly (i.e., by just using them).
• Using this directive requires us to explicitly
  declare them first. This helps in debugging code.
• Make sure this is the first line of code on all
  your ASP pages.
• We will be using Option Explicit on ALL programs
  from now on.

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Variable Naming

• Rules for naming variables
• Max 255 characters
• Must begin with a letter (e.g., Dim 1abc is
  illegal)
• No spaces
• Some symbols are illegal, best to only use a
  combination of letters, digits, and the - or
  _ characters when naming variables.
• Cannot used reserved words
• Dim dim is illegal

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Variable Naming Tips

• Be meaningful
• EmployeeBDate is more meaningful than Bdate
• Dont abbreviate too much
• Use comments to explain variable meaning (where
  appropriate)!!!
• Hungarian Notation
• Prefacing variable name with its data type
• intNum, strName, curPrice, dblPercent
• Pg. 137
• Not required in this class

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Initializing Variables (i.e., putting values in
them)

• We use the assignment operator to place a value
  into a variable
• TodaysTemp 31.5
• How different types of data are placed into
  variables
• String WelcomeMsg hello
• Number TodaysTemp 31.5
• Date IndpDay July 4, 1776
• Time LunchTime 12.00

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Arithmetic

• Addition, Subtraction, Multiplication, Division
  operators
• , -, , /
• Exponents
• NumSquared 102
• Negation
• NegativeNum -6
• Modulus (get the remainder only)
• Remainder 10 MOD 7
• Order of Operations
• P.E.M.D.A.S.
• Start in innermost parenthesis and work from left
  to right performing exponents, multiplication
  division, and addition subtractions. Then move
  to next innermost parenthesis and work from left
  to right again.

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String Fundamentals

• Concatenation
• Appending one string on to the end of another
• ExampleDim FirstName, LastName,
  FullNameFirstName JaneLastName
  SmithFullName FirstName LastName
• The variable FullName now contains the string
  Jane Smith.

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String Fundamentals Cont.

• Trim remove space characters from certain
  positions in a string.
• Trim() remove from front and back
• Rtrim() remove from right
• Ltrim() remove from left
• Length find number of characters in string
• Len()
• Dim StringSize, MyNameMyName
  ColinStringSize Len(MyName)
• StringSize is 5 (i.e., there are 5 characters in
  the string Colin)

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String Fundamentals Cont

• Case conversion change the case of a string
• UCase(), LCase()
• Dim LowerCaseStringLowerCaseString abc---
  outputs ABCResponse.Write UCase(LowerCaseString
  )
• Find a particular word in a string
• InStr(StringVariableToSearch, Text to search
  for)
• SearchStr 123abc--- outputs
  4Response.Write InStr(SearchStr, abc)
• abc starts at character 4 in the string
  123abc

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String Fundamentals Cont.

• Removing the ends of a string
• Left(string, number_of_characters)
• Right(string, number_of_characters)
• Example
• StrVar 123abc--- outputs 123Response.Write
  Left(StrVar, 3)
• Remove the middle of a string
• Mid(string, start, num_chars_to_extract)
• StrVar 123abc--- outputs 123aResponse.Wri
  te Mid(StrVar, 1, 4)

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Constants

• A constant is a variable whose value never
  changes during the execution of a program.
• Constants are a good way to represent values that
  seldom change, like the freezing point of water,
  or a phone number.
• Use ALL UPPERCASE letters to name constants
• Example
• Const WASHINGTON_POSTCODE WA

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Program 2

• TextArea a text box in which large amounts of
  text can be entered.
• lttextarea nametxtarea rows5 cols25gtEnter your
  data herelt/textareagt
• Mailto launches users email application when
  clicked with an email address preloaded.
• lta hrefmailtocfukai_at_gonzaga.edugtEmail Melt/agt
• Listbox
• ltselect namelistbox1 size3gt ltoptiongtvalue1lt/opt
  iongt ltoptiongtvalue2lt/optiongt
  ltoptiongtvalue3lt/optiongtlt/selectgt