Active Server Pages

1
Active Server Pages
2
Static Internet

• In the early days of the Internet, all
  information sent to clients browser was static.
• Little interactivity.
• Little functionality beyond simple hyperlinking.

3
Dynamic Internet, Part 1 (CGI)

• Common Gateway Interface (CGI) permits web
  browsers to request execution of application on
  the web server.
• The output of application is HTML code, which is
  sent to requesting browser.
• Separate CGI application loaded for each request.
• Development of client-side scripting languages
  especially JavaScript and VBScript.

4
Dynamic Internet, Part 2 (ISAPI)

• An alternative to CGI introduced by Microsoft.
• Uses dynamic link libraries (DLL). Once loaded,
  DLL stays in memory and answers user requests
  until explicitly released from memory.
• Normally faster than an equivalent CGI
  application.

5
ISAPI filter

• Custom DLL in same memory space as the web
  server, called by web server in response to every
  HTTP request.
• The filter tells the web server how to handle the
  request.
• The ASAPI filter allows you to customize the web
  servers response to specific types of user
  requests.

6
Examples of ASAPI filters

• Security layer between client and web server.
  Screens client request.
• Custom filter to map clients request to
  different location on the server.
• Custom filter to interpret information from
  server, and present the information in a
  different format. For example, ASP.DLL, which
  interprets server code and gives the client
  customized information

7
Active Server Pages

• In ASP.DLL.
• Whenever user requests a file with .asp
  extension, this ASAPI filter handles the
  interpretation.
• Loads scripting language interpreter DLLs.
• Executes server-side code.
• Passes resulting HTML to the web server, which
  forwards it to the browser.

8
Simple example

• ltHTMLgt
• ltBODYgt
• Hello.ltBRgt
• It is now approximately lt Time() gt at the
  server.
• ltPgt
• lt For i 1 to 5 gt
• ltFONT SIZE lt i gt gt
• Hello Size lt i gt lt/FONTgt ltBRgt
• lt Next gt
• lt/BODYgt
• lt/HTMLgt

9
Output of simple example
10
ASP Object Model

• ASP encapsulates the properties and methods of 6
  objects
• Application
• ASPError
• Request
• Response
• Server
• Session

11
Application Object

• Represents the ASP application itself
• One Application object for all users.
• Two methods
• Application_OnStart (triggered by first user)
• Application_OnEnd (triggered by administrator
  explicitly closing application.

12
ASPError Object

• To access properties of last error in currently
  executing script.
• Accessible only through Servers GetLastError
  method.

13
Request Object

• Access HTML form-based data and parameters sent
  over the address line.
• Receive HTTP cookie information.
• Receive client certificate information
• Get access to information in HTTP request header
  (via ServerVariables collection).

14
Response Object

• Controls how data is sent to client.
• Sends cookies to client, set expiration date.
• Redirects user to another URL.

15
Server Object

• Gives access to web server itself.
• Set timeout variables for scripts
• CreateObject method lets you create instances of
  server-side components. For example, ActiveX Data
  Objects to handle database access.

16
Session Object

• Holds information specific to users current
  session on the web server.

17
Server-Side Scripting

• ASP.DLL interprets code in .asp files thats
  delimited with lt gt.
• VBScript is the default scripting language.
• If the first statement is
• lt _at_LANGUAGEJscript gt
• you can change the scripting language.

18
Simple example

• ltHTMLgt
• ltBODYgt
• Hello.ltBRgt
• It is now approximately lt Time() gt at the
  server.
• ltPgt
• lt For i 1 to 5 gt
• ltFONT SIZE lt i gt gt
• Hello Size lt i gt lt/FONTgt ltBRgt
• lt Next gt
• lt/BODYgt
• lt/HTMLgt

19
Output of simple example
20
An example that uses Form Data

• lthtmlgt
• ltbodygt
• ltform method"POST" action"http//localhost/asp/e
  x2.asp"gt
• ltH2gtChoose your optionslt/H2gt
• ltselect name"favoriteBird"gt
• ltoption value"flamingo"gt Flamingo
• ltoption value"robin"gt Robin
• ltoption value"cardinal"gt Cardinal
• ltoption value"eagle"gt Eagle
• ltoption value"penguin"gt Penguin
• ltoption value"bluejay"gt Blue Jay
• lt/selectgt
• ltBRgt User Name ltinput typetext name"userName"gt
• ltBRgt Color ltinput typetext name"favoriteColor"gt
  
• ltBRgt ltinput typesubmit value"Send Data"gt
• lt/formgt
• lt/bodygt
• lt/htmlgt

21
The Users View
22
The ASP program

• ltHTMLgt
• ltHEADgt
• ltBODYgt
• lt username Request("userName") gt
• lt color Request("favoriteColor") gt
• lt bird Request("favoriteBird") gt
• ltFONT COLOR'lt Response.Write color gt' gt
• Hello, lt Response.Write userName gt. lt/FONTgt
• ltBRgt Your favorite bird is the lt Response.Write
  bird gt.
• Here is a picture!
• ltPgt ltIMG SRClt Response.Write bird gt.jpggt
• lt/BODYgt
• lt/HTMLgt

23
What the user sees
24
The generated code

• ltHTMLgt
• ltHEADgt
• ltBODYgt
• ltFONT COLOR'blue' gt
• Hello, John Avitabile. lt/FONTgt
• ltBRgt Your favorite bird is the eagle.
• Here is a picture!
• ltPgt ltIMG SRCeagle.jpggt
• lt/BODYgt
• lt/HTMLgt

25
An example using file access

• lthtmlgt
• ltbodygt
• ltform method"POST" action"http//localhost/asp/e
  x3.asp"gt
• ltH2gtChoose your favorite birdlt/H2gt
• ltselect name"favoriteBird"gt
• ltoption value"flamingo"gt Flamingo
• ltoption value"robin"gt Robin
• ltoption value"cardinal"gt Cardinal
• ltoption value"eagle"gt Eagle
• ltoption value"penguin"gt Penguin
• ltoption value"bluejay"gt Blue Jay
• lt/selectgt
• ltPgt ltinput typesubmit value"Send Vote"gt
• lt/formgt
• lt/bodygt
• lt/htmlgt

26
The ASP Program (part 1)

• lt Set fso CreateObject("Scripting.FileSystemObj
  ect") ' ActiveX
• voteFile "C\Inetpub\wwwroot\asp\votes.txt"
• Set tso fso.OpenTextFile(voteFile, 8, True)
  ' TextStreamObject
• ' 8 is append, 1 is read, 2 is write True
  means create if nec.
• Call tso.WriteLine(Request("favoriteBird"))
• Call tso.Close()
• Set tso fso.OpenTextFile(voteFile, 1, True)
• Dim vote(6)
• Do
• line tso.ReadLine
• Select Case line
• Case "flamingo"
• vote(1) vote(1) 1
• Case "robin"
• vote(2) vote(2) 1
• Case "cardinal"
• vote(3) vote(3) 1
• Case "eagle"
• vote(4) vote(4) 1

27
The ASP Program (part 2)

• Call tso.Close() gt
• ltHTMLgt
• ltHEADgt
• ltBODYgt
• lt bird Request("favoriteBird") gt
• Your vote for lt Response.Write bird gt has been
  recorded. Here are the
• totals so far.
• ltTABLE BORDER2 WIDTH50gt
• ltTRgt ltTDgt Flamingo lt/TDgt ltTDgt lt Response.Write
  vote(1) gt lt/TDgt lt/TRgt
• ltTRgt ltTDgt Robin lt/TDgt ltTDgt lt Response.Write
  vote(2) gt lt/TDgt lt/TRgt
• ltTRgt ltTDgt Cardinal lt/TDgt ltTDgt lt Response.Write
  vote(3) gt lt/TDgt lt/TRgt
• ltTRgt ltTDgt Eagle lt/TDgt ltTDgt lt Response.Write
  vote(4) gt lt/TDgt lt/TRgt
• ltTRgt ltTDgt Penguin lt/TDgt ltTDgt lt Response.Write
  vote(5) gt lt/TDgt lt/TRgt
• ltTRgt ltTDgt Blue Jay lt/TDgt ltTDgt lt Response.Write
  vote(6) gt lt/TDgt lt/TRgt
• lt/TABLEgt
• lt/BODYgt
• lt/HTMLgt

28
What the user sees
29
The generated code

• ltHTMLgt
• ltHEADgt
• ltBODYgt
• Your vote for eagle has been recorded. Here are
  the
• totals so far.
• ltTABLE BORDER2 WIDTH50gt
• ltTRgt ltTDgt Flamingo lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• ltTRgt ltTDgt Robin lt/TDgt ltTDgt 3 lt/TDgt lt/TRgt
• ltTRgt ltTDgt Cardinal lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• ltTRgt ltTDgt Eagle lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• ltTRgt ltTDgt Penguin lt/TDgt ltTDgt 1 lt/TDgt lt/TRgt
• ltTRgt ltTDgt Blue Jay lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• lt/TABLEgt
• lt/BODYgt
• lt/HTMLgt

30
Three Tier Architecture

• User Interface created using HTML, Dynamic HTML,
  or XML. Possibly including client-side scripts.
• Web server as middle tier that manipulates data
  from database via SQL queries and communicates
  with client Web browser.
• Database.

31
Accessing a database
lthtmlgt ltbodygt ltform method"POST"
action"http//localhost/asp/ex4.asp"gt ltPgt ltinput
typesubmit value"See Vote Totals"gt lt/formgt lt/bod
ygt lt/htmlgt
32
The ASP Program (part 1)

• lt ' Check for existing connection to Database
• If IsObject( Session("birdVotes_dbConn")) Then
• Set dbConn Session("birdVotes_dbConn")
• Else
• Set dbConn Server.CreateObject(
  "ADODB.Connection" )
• Call dbConn.Open("birdVotes","","") ' ODBC
  registered
• Set Session("birdVotes_dbConn") dbConn
• End If
• dbQuery "SELECT FROM Votes"
• ' Create recordset
• Set votesRS Server.CreateObject(
  "ADODB.Recordset")
• Call votesRS.Open( dbQuery, dbConn)
• ' move to first record in recordset
• Call votesRS.MoveFirst() gt

33
The ASP Program (part 2)

• ltHTMLgt
• ltHEADgt
• ltBODYgt
• lth1gt Votes Already Cast lt/h1gt
• ltTABLE BORDER2 WIDTH50gt
• ltTRgt ltTHgt Voter lt/THgt ltTHgt Bird lt/THgt lt/TRgt
• lt While Not votesRS.EOF gt
• ltTRgt ltTDgt lt votesRS("Voter") gt lt/TDgt
• ltTDgt lt votesRS("Bird") gt lt/TDgt
  lt/TRgt
• lt Call votesRS.MoveNext()
• Wend gt
• lt/TABLEgt
• lt/BODYgt
• lt/HTMLgt

34
What the user sees
35
The generated code

• ltHTMLgt ltHEADgt ltBODYgt
• lth1gt Votes Already Cast lt/h1gt
• ltTABLE BORDER2 WIDTH50gt
• ltTRgt ltTHgt Voter lt/THgt ltTHgt Bird lt/THgt lt/TRgt
• ltTRgt ltTDgt Babe Ruth lt/TDgt
• ltTDgt flamingo lt/TDgt lt/TRgt
• ltTRgt ltTDgt Lou Gehrig lt/TDgt
• ltTDgt penguin lt/TDgt lt/TRgt
• ltTRgt ltTDgt Joe DiMaggio lt/TDgt
• ltTDgt cardinal lt/TDgt lt/TRgt
• ltTRgt ltTDgt Mickey Mantle lt/TDgt
• ltTDgt bluejay lt/TDgt lt/TRgt
• ltTRgt ltTDgt Reggie Jackson lt/TDgt
• ltTDgt eagle lt/TDgt lt/TRgt
• ltTRgt ltTDgt Don Mattingly lt/TDgt
• ltTDgt flamingo lt/TDgt lt/TRgt
• ltTRgt ltTDgt Mariano Rivera lt/TDgt
• ltTDgt penguin lt/TDgt lt/TRgt
• ltTRgt ltTDgt Derek Jeter lt/TDgt

36
Inserting, Updating, Complex queries

• lthtmlgt
• ltbodygt
• ltform method"POST" action"http//localhost/asp/e
  x5.asp"gt
• ltH2gtChoose your favorite birdlt/H2gt
• ltselect name"favoriteBird"gt
• ltoption value"flamingo"gt Flamingo
• ltoption value"robin"gt Robin
• ltoption value"cardinal"gt Cardinal
• ltoption value"eagle"gt Eagle
• ltoption value"penguin"gt Penguin
• ltoption value"bluejay"gt Blue Jay
• lt/selectgt
• ltPgt Name ltinput typetext nameuserNamegt
• ltPgt ltinput typesubmit value"Send Vote"gt
• lt/formgt
• lt/bodygt
• lt/htmlgt

37
ASP Program (part 1)

• lt ' Check for existing connection to Database
• If IsObject( Session("birdVotes_dbConn")) Then
• Set dbConn Session("birdVotes_dbConn")
• Else
• Set dbConn Server.CreateObject(
  "ADODB.Connection" )
• Call dbConn.Open("birdVotes","","") ' ODBC
  registered
• Set Session("birdVotes_dbConn") dbConn
• End If
• dbQuery "SELECT FROM Votes"
• ' Create recordset
• Set votesRS Server.CreateObject(
  "ADODB.Recordset")
• Call votesRS.Open( dbQuery, dbConn)
• ' move to first record in recordset

38
ASP Program (part 2)

• Call votesRS.MoveFirst()
• previousVote False
• message Request("userName") ","
• While Not votesRS.EOF
• If Request("userName") votesRS("Voter")
  Then
• message message " you changed your vote
  from " _
• votesRS("Bird") " to "
  Request("favoriteBird")
• sqlString "UPDATE Votes SET Bird '"
  Request("favoriteBird") _
• "' WHERE Voter '"
  Request("userName") "'"
• dbConn.Execute(sqlString)
• previousVote True
• End If
• Call votesRS.MoveNext()
• Wend

39
ASP Program (part 3)

• If previousVote False Then
• message message " your vote for "
  Request("favoriteBird") _
• " has been recorded"
• sqlString "INSERT INTO Votes VALUES ('"
  Request("userName") _
• "', '" Request("favoriteBird")
  "')"
• dbConn.Execute(sqlString)
• End If
• gt
• ltHTMLgt
• ltHEADgt
• ltBODYgt
• lt message gt
• ltTABLEgt
• ltTRgt ltTHgt Bird lt/THgt ltTHgt Votes lt/THgt lt/TRgt

40
ASP Program (part 4)

• lt dbQuery "SELECT Votes.Bird, COUNT() AS
  BirdCount FROM Birds " _
• "INNER JOIN Votes " _
• "ON Birds.Bird Votes.Bird GROUP BY
  Votes.Bird"
• Set birdsRS Server.CreateObject(
  "ADODB.Recordset")
• Call birdsRS.Open( dbQuery, dbConn)
• ' move to first record in recordset
• Call birdsRS.MoveFirst()
• While Not birdsRS.EOF
• gt
• ltTRgt ltTDgt lt birdsRS("Bird") gt lt/TDgt
• ltTDgt lt birdsRS("BirdCount") gt lt/TDgt
  lt/TRgt
• lt
• Call birdsRS.MoveNext()
• Wend gt
• lt/TABLEgt
• lt/BODYgt
• lt/HTMLgt

41
What the User Sees
42
Code generated

• ltHTMLgt
• ltHEADgt
• ltBODYgt
• Thurman Munson, you changed your vote from
  robin to penguin
• ltTABLEgt
• ltTRgt ltTHgt Bird lt/THgt ltTHgt Votes lt/THgt lt/TRgt
• ltTRgt ltTDgt bluejay lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• ltTRgt ltTDgt cardinal lt/TDgt ltTDgt 1 lt/TDgt lt/TRgt
• ltTRgt ltTDgt eagle lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• ltTRgt ltTDgt flamingo lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• ltTRgt ltTDgt penguin lt/TDgt ltTDgt 3 lt/TDgt lt/TRgt
• ltTRgt ltTDgt robin lt/TDgt ltTDgt 2 lt/TDgt lt/TRgt
• lt/TABLEgt
• lt/BODYgt
• lt/HTMLgt