Server Side Scripting

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Server Side Scripting

• Introduction To ASP

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How Server Side Scripting Works
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Active Server Pages

• An Active Server Page (ASP) is an HTML page that
  includes one or more server side scripts.
• Used with Microsoft servers
• PWS and Windows 98
• IIS and later versions of Windows
• Has a .asp extension
• Generally use VBScript but can use JScript
• Has tags lt ASP code in here gt

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ASP (Cont)

• Usually tailoring a page for the user.  
• Used in many applications
• Dynamic individualisation of a page
• Extraction of data from a database

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Where you can get ASP access

• Using your ASP account at the university
• W drive
• View via http//internalasp.soc.staffs.ac.uk/stude
  nt/
• Using many free ASP web areas
• e.g. www.Brinkster.com
• Most have adverts

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The Main Objects

• Response
• Session
• Request
• Server
• Application

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Response Object

• It is the object which communicates between the
  server and the output which is sent to the
  client.
• ltbodygt   lt Response.Write("Hello, World!") gt
• lt/bodygt
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex1.asp

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Response Object (Cont)

• You can add HTML formatting in the
  response.write.
• lt response.write(ltpgtltfont faceArial
  size4gtltbgtHello World lt/bgtlt/fontgt lt/pgt)gt
• You can invoke the Response.Write method by using
  the equals () sign. The simulates
  Response.Write.
• lt"Hello, World!" gt
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex2.asp

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Simple Debugging

• You can use the response.write as a debugging
  tool to show where your program gets to before it
  crashes, or to see what results you are getting.

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Redirecting using ASP

• Sometimes, you may wish to redirect the user to a
  different URL automatically.
• Response.Redirect URL
• Must go before all HTML tags

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• Loops and Conditionals

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For Loops

• You can use FOR in ASP just as you can in
  standard programming
• lt FOR I1 to 10
• Response.write(Hello worldltbrgt)
• NEXT gt
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex3.asp

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If Statement

• If then
• first bit code
• Else
• If then
• Second bit code
• End if
• End if
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex4.asp

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Case Statements

• Used instead of multiple ifs
• Select Case myVarA    Case "1"        Response.W
  rite("a1")    Case "2"        Response.Write("a
  2")    Case "3"        Response.Write("a3")  
    Case Else    Response.Write("a equals
  something else...")End Select
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex11.asp

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ASP

• Variables

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Variables

• In ASP code, you do not have to declare
  variables. You just access them by saying
• VAR1 23
• VAR2 Fred Bloggs
• Variable names
• must start with alphabetical character
• can't contain any full stops or reserved words
• must be unique and be 255 characters or less
• Variable naming should always stick to one style,
  like strLastName for strings

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Local Variables

• Within an ASP script
• Which can only be referenced when that page is
  executed.
• VAR2 Fred Bloggs

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Session Objects and Session Variables

• A session is from when a browser is opened to
  when it is shut, or when a certain time has
  elapsed.
• Session Variables are stored in memory on your
  server.
• You can set session variables at any point.
• Useful if you want to remember a value from one
  page to the next
• E.g. When you log in to a website a session
  variable is set. This way you don't have to
  retype in your username and password for every
  page you go to.

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Session Variables

• session(VARIABLENAME) Fred Bloggs
• Response.Write(Session("VarName"))
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspvar.asp
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex8.asp

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Session Object

• Session.SessionID - the unique session identifier
  set automatically.
• Session.TimeOut - amount of time in minutes that
  a session will stay alive.
• To change - Session.TimeOut NumberOfMinutes
• This time, in minutes, is how long your session
  variables will be accessible. Unless the user
  closes their browser, then all session variables
  will be cleared. The default for the
  Session.TimeOut is 30 minutes.

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Adding variables together

• You can add two numeric variables together using
  the sign
• lt Age 20
• Pi 3.14159
• Response.write(Age Pi) gt
• You can do the same with two text variables
• If you attempt to add a string to a number you
  get an error message
• You can use the rather than the sign to treat
  all the variables as text
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex5.asp

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Checking the type of a variable

• You may need to check the type of a variable. You
  can do this by using functions like
• IsDate()
• IsNumeric()
• IsEmpty() whether a variable has been
  initialised
• IsNull()

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Example

• lt
• MyName Scott Mitchell
• MyAge 21
• Response.Write(IsNumeric(MyAge))
• Response.Write(ltbrgt)
• Response.Write(IsDate(MyName))
• If not IsDate(MyName) then
• response.write("Silly person...its not a
  date")
• end if
• gt http//asp.soc.staffs.ac.uk/student/flk1/exam
  ples/aspex6.asp

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Converting Variables

• You can make sure the variable is of a certain
  type by converting it using a function.
• CBool Function - Converts to a Boolean
• CByte Function - Converts to a Byte
• CCur Function - Converts to a Currency
• CDate Function - Converts to a Date
• CDbl Function - Converts to a Double
• CInt Function - Converts to a Integer
• CSng Function - Converts to a Single
• CStr Function - Converts to a String

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Converting Variables (Cont)

• All of these functions take one parameter, a
  variable, and return a variable of the requested
  subtype.
• To convert one variable to a particular subtype
  use the following syntax
• var1 CStr(var1)

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Formatting Variables

• FormatCurrency(var1)
• FormatPercent(var1)
• Lcase(var1)/ Ucase(var1)
• Left(var1, length) / Right(var1, length)
• Mid(var1,start,length)
• Len(var1)
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex7.asp

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Arrays

• Arrays in ASP have a zero based index.
• This means that the first item in the array is
  myArray(0).
• The size of arrays in ASP can be changed while
  still maintaining the data that is currently in
  them.

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Arrays(Cont)

• How to create
• Dim myArray(2) / Dim myArray()
• How to enlarge
• ReDim Preserve myArray(3)
• NOTE If you are creating a small array you can
  also create it like this
• FavoriteFoodArray Array(fried eggs", beef
  burgers",chips")
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex9.asp

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Date and Time Functions

• yyyy - Year
• q - quarter
• m - Month
• y - Day of Year
• d - Day
• w - Weekday
• ww - Week of Year
• h - Hour
• n - Minute
• s - Second

• Month(date1), Day(date1), Year(date1)
• Hour(time1), minute(time1)
• monthname(month(date1))
• DateAdd(interval, number, date)
• DateDiff(interval, date1, date2)
• DatePart(interval, date1)
• FormatDateTime(Date)
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex12.asp

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• Functions and Subroutines

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Sub Routines and Functions

• Useful if you are using the same bit of code more
  than once.
• Sub Routines do not return a value whereas
  functions do.
• lt Function FunctionName(parameters passed in)
• 'Code for Function...
• Returns value
• End Function gt
• lt Sub SubroutineName( Parameters to Pass In )
• 'Code for Sub...
• End sub gt

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Example

• ' This function takes two integers and adds them
  together.
• Function Add(intA, intB)
• intResult intA intB
• Add intResult
• End Function
• gt
• ltpgt1 2 lt Add(1,2) gtlt/pgt
• ltpgt534 3142 lt Add(534,3142) gtlt/pgt
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex10.asp

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ASP

• Using ASP with Forms

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Request Object

• The Request Object is used to get information
  from an html form or on the query string
• Forms
• Post
• Get
• Using the URL with a ?
• Fred.asp?var16

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From A Form POST

• In form1.htm
• ltform method"POST" action"formresult.asp"gt
• My Text Box ltinput type"text" name"myvar"
  size"20"gt
• ltinput type"submit" value"Submit"gt
• lt/formgt
• In formresult.asp
• lt
• formvar request.form("myvar")
• response.write(formvar)
• gt http//asp.soc.staffs.ac.uk/student/flk1/examp
  les/aspex13.htm

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From A Form GET

• In form1.htm
• ltform methodGET" action"formresult.asp"gt
• My Text Box ltinput type"text" name"myvar"
  size"20"gt
• ltinput type"submit" value"Submit"gt
• lt/formgt
• In formresult.asp
• lt
• formvar request.querystring("myvar")
• response.write(formvar)
• gt http//asp.soc.staffs.ac.uk/student/flk1/examp
  les/aspex14.htm

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From A URL

• Works the same as a GET
• In formresult.asp?myvarfred
• lt
• formvar request.querystring("myvar")
• response.write(formvar)
• gt
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex14b.asp?myvarxfred

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From A Combination

• In form1.htm
• ltform method"POST" action"formresult.asp?myvar2
  6"gt
• My Text Box ltinput type"text" name"myvar"
  size"20"gt
• ltinput type"submit" value"Submit"gt
• lt/formgt
• In formresult.asp
• lt
• formvar request.form("myvar")
• Formvar2 request.querystring(myvar2)
• response.write(formvar)
• Response.write(formvar2)
• gt http//asp.soc.staffs.ac.uk/student/flk1/exampl
  es/aspex15.htm

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Posting To The Original ASP Page

• You may also in a form wish to have an action
  which posts to the same page.
• Useful for validation
• Useful if the response given by the user affects
  the page that the user is sent to (Using
  response.redirect)
• http//asp.soc.staffs.ac.uk/student/flk1/examples/
  aspex16.asp

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Comments

• Comments within ASP tags are done with a single
• ltBODYgtlt
• Response.Write("Hello, World!")
• This is a comment
• This is another comment
• gt
• lt/BODYgt

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Next Week

• ASP and databases
• Include Files
• More loops
• Sources Of ASP Code
• Error Messages