ASP HistoryComponents

1
ASP History/Components

• Active Server History
• Introduced July 1996
• Bundled with Internet Information Server (IIS)
  3,0 March of 1997
• ASP 2.0 introduced in 1998 Shipped with IIS 4.0
• AS 3.0 shipped as part of Windows 2000 IIS 5.0
• IS considered to be more of a Technology than a
  language
• It's syntax is comprised of a ASP, HTML tags and
  pure text.

2
ASP Capabilities

• ASP can
• Generates dynamic web pages
• Processes the contents of HTML forms
• Creates database driven web pages
• Tracks user sessions can store information about
  users from the moment they arrived at web site
  tell the moment they leave.
• Create searchable web pages
• Detect capability different browsers
• Send e-mail
• Integrate custom components of your Web site
  including server side components created with
  Visual Basic ,C or Java.

3
ASP Flexibility

• Static
• VS
• Dynamic
• Websites

4
Simple Page

• ltHTMLgt
• ltHEADgt ltTITLEgt Hungry ASP Example lt/TITLEgt
  lt/Headgt
• ltBODYgt
• lt
• For i 1 to 10
• varvar"very,"
• Response.Write(i""var"ltBRgt")
• NEXT
• gt
• ltHRgt
• I am ltvargt Hungry!!
• lt/BODYgt
• lt/HTMLgt

5
Object Overview

• Objects Contain
• Methods
• Determine the things
• Properties
• Can be used to set the state of and object
• Collections
• Constitutes a set of Keys and Value pairs
  related to the object.

6
Object Example

• A Dictionary
• Methods
• Look things up, used as a door stop.
• Properties
• Has a certain number of pages, and a particular
  author.
• Collections
• Each section corresponds to the text it
  contains.

7
ASP Components

• Ad rotator component - used to display banner
  advertisements on pages a WebSite.
• Web browsers capabilities component - to be used
  to display different HTML content according to
  the capabilities of different browsers. For
  example you can use is component to display Web
  pages with frames only to frames compliant
  browsers.
• Content linking component- is used to live
  together several HTML pages so they can be
  navigating easily. for example you can use this
  component display the pages that online book
• Counters component -the counters component and
  keep track of the number of visitors to your
  WebSite. You can use the counters component add a
  hit counter to a Web page.

8
ASP Components (cont)

• Content rotator component - can be used to rotate
  through HTML content I page. For example you can
  use the component to randomly display different
  announcements on the home page of your WebSite.
• Page counter - is exactly like counter component
  into the used to track visitors into a hit
  counter to a particular Web page.
• Permissions checker component- can be used to
  display links to Web pages only to those users to
  their permission to see them.
• Collaboration data objects the collaboration data
  objects enables sending and retrieving of
  information from within your active server pages.
  For example you can send an email after a new
  user registers at your WebSite
• ActiveX data objects enabling you to retrieve
  information stored in a databases.

9
Page Scope

• Page scope- is created on a single page and dies
  when the processing of the page ends
• Can be created with server.Createobject() or the
  HTML ltobjectgt tag.

10
Page Scope Example

• ltHTMLgt
• ltHEADgtltTITLEgt Objectst - ASP Examplelt/TITLEgtlt/HEAD
  gt
• ltBODYgt
• lt
• set MydictServer.CreateObject("Scripting.Dictiona
  ry")
• MyDict.Add "CA", "California"
• MYDict.Add "OH", "OHIO"
• MyDict.Add "FL", "Florida"
• gt
• My dictionary has ltMydict.countgt entries.
• ltBRgt
• The first entry is ltMydict.Item("CA")gt
• ltBRgt
• lt/BODYgt
• lt/HTMLgt

11
Session Scope

• Components are created for each visitor to your
  web site
• Components do not leave memory until the visitor
  leaves your website

12
Buffering

• Can be set as a default for the website IIS
  Enable Buffering
• Will not send page until the script completely
  processes
• Response.BufferTrue must appear before any HTML
  or Script output otherwise an error will be
  issued.

13
Caching

• Browsers will sometimes present a page from
  Cache instead of retrieving it from the
  website.
• The browser can be set to always go to the
  website for pages
• ASP provides Expires, ExpiresAbsolute for
  websites and CacheControl (for proxy servers)
• Response.Expires 0 sets the page life to 0
  minutes and will always request fresh pages
• Response.ExpiresAbsolute Jan 1, 2010
  000000 set the page to expire on midnight of
  12/31/2009
• Response.CacheControl Public means anyone
  can use the page, Private does not cache the
  pages

14
ASP Status Codes

• 1xx - Informational - Expermental
• 2xx - Success
• 3xx - Redirection
• 4xx - Client Error
• 5xx - Server Error

15
Navigating your User

• On occasion, you will need to redirect your user
  to another page. (Access rights, Registration,
  Form completion etc)
• Response.Redirect path/page.asp
• Must be used before any text is outputted to the
  browser
• Buffering may need to be utilized.

16
Request Object

• Contains all of the information about the HTTP
  request performed to retrieve an Active Server
  Page
• The request object contains three collections
• Querystring used to pass information form the
  browser to the server. It appears after the ?
• FormCollection - similar to the query string
  used to store variables posted within a HTML form
• Server Variables when a browser requesta a web
  page from a server, the request contains several
  headers

17
Request Object Query String

• Are typically not entered directly into the
  address bar of a browser .
• Firstpage.ASP
• lthtmlgt
• ltheadgtlttitlegtColor Choicelt/titlegtlt/headgt
• What is your favorite color?
• ltPgt
• lta href"nextpage.asp?favcolorblue"gtbluelt/agt
• ltpgt
• lta href"nextpage.asp?favcolorred"gtredlt/agt
• lt/bodygt
• lt/htmlgt

18
Query String Example

• NextPage.ASP
• lthtmlgt
• ltheadgtlttitlegtYour Favorite Colorlt/titlegtlt/headgt
• ltbodygt
• lt
• favColor Request.QueryString( "favColor" )
• gt
• Your favorite color is ltfavColorgt!
• lt/bodygt
• lt/htmlgt

19
URL Encoded Query String

• Used when the value of a query string contains a
  non alphanumeric character such as a space,
  quotation mark, comma period, etc .
• lta hrefmenupage.asp?favfoodchocolate
  cake"gtChocolate Cakelt/agt
• Would need to be implemented as follows
• lt
• favfood Server.URLEncode (Chocolate Cake)
• gt
• lta hrefmenupage.asp?favfoodltfavfoodgt
  "gtChocolate Cakelt/agt

20
Multiple Query String Variables

• You can pass multiple variables in the query
  string by utilizing the
• ...
• lta hreforder.asp?entrée steakdrinkpepsi"gtStea
  k and Pepsilt/agt
• ...
• order.asp
• lt
• Response.Write Request.QueryString(entrée)
• Response.Write Request.QueryString(drink)
• gt
• You can pass multiple values to a variables in
  the query string by utilizing the
• ...
• lta hrefFlag.asp?fcolorredwhiteblue"gtUSAlt/agt
• lt
• Response.Write Request.QueryString(fcolor)
• gt
• Would produce red, white, blue

21
Dumping QueryString Collection

• Mostly used in debugging an Active Server Page.
• You can use a for.. next loop lt
• for i 1 to Request.QueryString.Count
• Response.Write Request.QueryString(i) ltbrgt)
• next
• gt
• You can also use a for.. each loop
• lt
• for each thing in Request.QueryString
• Response.Write thing
  Request.QueryString(thing) ltbrgt)
• next
• gt

22
Query Strings Pros/Cons

• Can be useful for passing small bits of
  information.
• Always displayed in clear text do not use for
  passing hidden data or large chunks of data.
• Different browsers handle a different maximum
  limits of query string lengths

23
Request Object

• Contains all of the information about the HTTP
  request performed to retrieve an Active Server
  Page
• The request object contains three collections
• Querystring used to pass information form the
  browser to the server. It appears after the ?
• FormCollection - similar to the query string
  used to store variables posted within a HTML form
• Server Variables When a browser requests a web
  page from a server it includes several headers
  which can be queried using this collection.

24
Forms Collection

• The forms collection is very similar to the
  querystring collection.
• FormCollection - similar to the query string
  used to store variables posted within a HTML form

25
Form Example

• Color.ASP
• lt
• Dim color, state
• color "Blue"
• state "Ohio"
• Function checked(firstVal, secondVal)
• If firstVal secondVal then
• checked " CHECKED"
• End if
• End Function
• Function selected(firstVal, secondVal)
• If firstVal secondVal then
• checked " SELECTED"
• End if
• End Function
• gt
• lthtmlgt
• ltheadgtlttitlegtColor Choice using
  Buttonslt/titlegtlt/headgt
• lt/bodygt

26
Form Example

• Colorp.ASP
• lt
• for each thing in request.form
• Response.Write thing " "Request.form(thing)
  "ltbrgt"
• next
• DIM state,color
• stateRequest.Form("state")
• colorRequest.Form("color")
• gt
• lthtmlgt
• ltheadgtlttitlegtColors ..lt/titlegtlt/headgt
• ltbodygt
• Do all of the people who live in ltstategt have
  ltcolorgt as their favorite color??
• lt/bodygt
• lt/htmlgt

27
Form Example

• Comment.ASP
• lthtmlgt
• ltheadgtlttitlegtYour Comments Matterlt/titlegtlt/headgt
• ltbodygt
• ltform method"post" action"confirm.asp"gt
• ltpgtPlease enter your name (L,F ) lt/bgt
• ltinput name"username" type"text" size30gt
• ltpgt Please enter your comments
• ltbrgt lttextarea name"comments" cols40 rows5gt
  lt/textareagt
• ltinput type"submit" value"Send comments"gt
• lt/formgt
• lt/bodygt
• lt/ht

28
Form Example

• Confirm.asp
• lt
• DIM username,comments
• usernameRequest.Form(username)
• commentsRequest.Form(comments)
• gt
• lthtmlgt
• ltheadgtlttitlegtThanks ..lt/titlegtlt/headgt
• ltbodygt
• Your name is ltusernamegt
• Your comments are ltcommentsgt
• lt/bodygt
• lt/htmlgt

29
Form Example

• Confirm.asp
• lt
• DIM username,comments
• usernameRequest.Form(username)
• commentsRequest.Form(comments)
• gt
• lthtmlgt
• ltheadgtlttitlegtThanks ..lt/titlegtlt/headgt
• ltbodygt
• Your name is ltusernamegt
• Your comments are ltcommentsgt
• lt/bodygt
• lt/htmlgt

30
Form Example

• Confirm.asp
• lt
• DIM username,comments
• usernameRequest.Form(username)
• commentsRequest.Form(comments)
• gt
• lthtmlgt
• ltheadgtlttitlegtThanks ..lt/titlegtlt/headgt
• ltbodygt
• Your name is ltusernamegt
• Your comments are ltcommentsgt
• lt/bodygt
• lt/htmlgt

31
Request Object

• Contains all of the information about the HTTP
  request performed to retrieve an Active Server
  Page
• The request object contains three collections
• Querystring used to pass information form the
  browser to the server. It appears after the ?
• FormCollection - similar to the query string
  used to store variables posted within a HTML form
• Server Variables When a browser requests a web
  page from a server it includes several headers
  which can be queried using this collection.

32
Include Files

• Are used like copy books to create function or
  code libraries
• Syntax
• lt!-- INCLUDE VIRTUAL /path/file.inc--gt
• File does not nee to have the inc extension -
  common practice.

33
Server Variables

• The ServerVariables collection retrieves the
  values of environment variables.
• Request.ServerVariables (variable)
• variable
• Specifies the name of the server environment
  variable to retrieve. It can be one of the
  following values.
• Variable Description
• AUTH_TYPE The authentication method that the
  server uses to validate users when they attempt
  to access a protected script.
• CONTENT_LENGTH The length of the content as
  given by the client.
• CONTENT_TYPE The data type of the content. Used
  with queries that have attached information,
  such as the HTTP queries POST and PUT.
• GATEWAY_INTERFACE The revision of the CGI
  specification used by the server. Format
  CGI/revision
• HTTP_ltHeaderNamegt The value stored in the header
  HeaderName. Any header other than those listed
  in this table must be prefixed by HTTP_ in
  order for the ServerVariables collection to
  retrieve its value.
• Note The server interprets any underscore (_)
  characters in HeaderName as dashes in the actual
  header. For example if you specify
  HTTP_MY_HEADER, the server searches for a header
  sent as MY-HEADER.

34
Server Variables (Continued)

• LOGON_USER The Windows NT account that the user
  is logged into.
• PATH_INFO Extra path information as given by the
  client. You can access scripts by using their
  virtual path and the PATH_INFO server variable.
  If this information comes from a URL it is
  decoded by the server before it is passed to the
  CGI script.
• PATH_TRANSLATED A translated version of PATH_INFO
  that takes the path and performs any necessary
  virtual-to-physical mapping.
• QUERY_STRING Query information stored in the
  string following the question mark (?) in the
  HTTP request.
• REMOTE_ADDR The IP address of the remote host
  making the request.
• REMOTE_HOST The name of the host making the
  request. If the server does not have this
  information, it will set REMOTE_ADDR and leave
  this empty.
• REQUEST_METHOD The method used to make the
  request. For HTTP, this is GET, HEAD, POST, and
  so on.
• SCRIPT_MAP Gives the base portion of the URL.
• SCRIPT_NAME A virtual path to the script being
  executed. This is used for self-referencing URLs.
  
• SERVER_NAME The server's host name, DNS alias,
  or IP address as it would appear in
  self- referencing URLs.
• SERVER_PORT The port number to which the request
  was sent.

35
Server Variables (Continued)

• SERVER_PORT_SECURE A string that contains either
  0 or 1. If the request is being handled on the
  secure port, then this will be 1. Otherwise, it
  will be 0.
• SERVER_PROTOCOL The name and revision of the
  request information protocol. Format
  protocol/revision
• SERVER_SOFTWARE The name and version of the
  server software answering the request (and
  running the gateway). Format name/version
• URL Gives the base portion of the URL.
• Query_String Gives the portion of the URL after
  the ?

36
Server Variables Example

• Servervar.asp
• ltHTMLgt
• ltHEADgtltTITLEgt server variableslt/TITLEgtlt/HEADgt
• ltBODYgt
• the time is ltTIMEgt
• lt
• for each name in request.servervariables
• response.write ("ltpgtltBgt"name"lt/bgt")
• response.write (request.servervariables(name))
• Next
• gt
• lt/BODYgt
• lt/HTMLgt

37
File Passing - Upload

• File Uploads allows the web visitor the
  capability of passing a file to the website.
• ltHTMLgt
• ltHEADgtltTITLEgt File Upload lt/TITLEgtlt/HEADgt
• ltBODYgt
• ltFORM ENCTYPE"multipart/form-data"
• ACTION"upresult.asp" METHODPOSTgt
• Please choose a picture to upload
• ltBRgtltINPUT NAME"picture" TYPEFILE
  ACCEPT"image/"gt
• ltBRgtltINPUT TYPESUBMIT VALUE"Submit Me!"gt
• lt/FORMgt
• lt/BODYgt
• lt/HTMLgt

38
File Passing - Retrieve

• To process the uploaded file
• Upresults.asp
• lt
• FormSize Request.TotalBytes
• FormData Request.BinaryRead( FormSize )
• bnCRLF chrB( 13 ) chrB( 10 )
• Divider LEFTB( FormData, INSTRB( FormData,
  bnCRLF ) - 1 )
• DataStart INSTRB( FormData, bnCRLF bnCRLF )
  4
• DataEnd INSTRB( DataStart 1, FormData,
  divider ) - DataStart
• Response.ContentType "image/gif"
• Response.BinaryWrite MIDB( FormData, DataStart,
  DataEnd )
• gt

39
ODBC

• Open Database Connectivity (ODBC) is a standard
  or open application programming interface
  (application program interface) for accessing a
  database. By using ODBC statements in a program,
  you can access files in a number of different
  databases, including Access, Oracle, Sybase SQL
  Server, DB2. ODBC allows programs to use SQL
  requests that will access databases without
  having to know the proprietary interfaces to the
  databases. ODBC handles the SQL request and
  converts it into a request the individual
  database system understands.

40
Making An Oracle Connection

• DBinq.asp
• lt
• set conn server.createobject("ADODB.Connection
  ")
• conn.open "Oracleadd","system","manager"
• set rs server.createobject("ADODB.Recordset")
• SQLSTR "SELECT from system.address order
  by lastname"
• rs.open SQLSTR, conn, 3, 3
• while not rs.eof
• ln rs.fields("lastname")
• response.write ln "ltbrgt "
• rs.movenext
• wend
• conn.close
• set rs nothing
• set conn nothing
• gt
• lt/bodygt
• lt/htmlgt

41
Making An Oracle Connection

• For a Connection object
• connection.Open ConnectionString, UserID,
  Password
• For a Recordset object
• recordset.Open Source, ActiveConnection,
  CursorType, LockType
• The Open method syntax has these parts.
• Part Description
• Connection An object variable representing an
  existing Connection object.
• recordset An object variable representing an
  existing Recordset object.
• ConnectionString Optional. A String containing
  connection information. See the ConnectionString
  property for details on valid settings.
• UserID Optional. A String containing a user name
  to use when establishing the connection.
• Password Optional. A String containing a password
  to use when establishing the connection.
• Source Optional. A Variant that evaluates to a
  valid Command object variable name, an SQL
  statement, a table name, or a stored procedure
  call.
• ActiveConnection Optional. A Variant that
  evaluates to a valid Connection object variable
  name or a String containing a definition for a
  connection.

42
Making An Oracle Connection

• CursorType Optional. A CursorTypeEnum value that
  determines the type of cursor that the provider
  should use when opening the Recordset. Can be one
  of the following constants
• adOpenForwardOnly, 0 (Default)
• adOpenKeyset, 1
• adOpenDynamic, 2
• adOpenStatic, 3
• LockType Optional. A LockTypeEnum value that
  determines what type of locking (concurrency) the
  provider should use when opening the Recordset.
  Can be one of the following constants
• adLockReadOnly, 1
• adLockPessimistic, 2
• adLockOptimistic, 3
• adLockBatchOptimistic, 4
• See the LockType property for definitions of
  these settings.

43
Sessions

• A session is something that starts the moment a
  user request something from your website and ends
  soon after they leave
• Each visitor of your website is given a unique
  session.
• Sessions can be used to maintain preferences
  background color, frames, text only version etc.
• Sessions can also track purchase requests
  (Virtual Shopping Carts) and checkout all at
  once.
• Sessions can track the habits of your visitors as
  they roam from page to page. Useful for
  advertisements and overall web design
  improvements.

44
Sessions Variables

• Session variables work much like application
  variables.
• Main difference separate copies session variables
  are automatically created for each visitor.
• Sessions use cookies
• A unique identifier is created for each visitor
  and persists until they leave
• A time threshold Is set to expire the session
• ltSession.Timeout20gt

45
The State of Sessions

• HTTP by nature is a simple set comprised of a
  request and response.
• Each visit to a website is a new request
  regardless if it is the same visitor from the
  same browser.
• This nature of HTTP creates a serious restriction
  in your ability to identify a user over multiple
  web pages.

46
Sessions -Cookies

• The cookie is created in the user's browser
• The purpose is to create a unique identifier(an
  activeX component object), to manage the
  session, when the session ends the cookie
  expires.
• Response.Cookies(username) Jim Smith will
  create a cookie to persist information
• There are four Microsoft ActiveX component
  threading models that can be used when creating a
  component for use with Active Server Pages
• Single-Threaded (not recommended)
• Apartment-Threaded (recommended)
• Free-Threaded (not recommended)
• Objects Marked as Both (highly recommended)

47
Single-Threaded Components

• This threading model is not recommended for
  components that will be called by Active Server
  Pages.
• Single-threaded objects run in exactly one
  thread, the one that called the CoInitialize
  method. Calls to these objects from other threads
  are marshaled to this thread. Only one thread at
  a time can enter a set of single-threaded
  objects, and it must be the same thread each
  time.
• The Web server creates a parked thread that calls
  CoInitialize, and then marshals object calls to
  itself.
• One disadvantage of single-threaded objects is
  that they cannot be stored in the Application
  object. The only way to create a single-threaded
  object with application scope is to declare it
  with an ltOBJECTgt tag. However, when this object
  is used, the Web server will lock the application
  down to a single thread, the one that created the
  object. This will reduce server performance
  significantly, and should only be considered for
  intranet applications.
• In addition, if a single-threaded object is
  created with session scope or is stored in the
  Session object, the Web server will lock the
  session down to the single thread that created
  the object.

48
Apartment-Threaded

• This threading model is recommended for
  components called by ASP.
• Each apartment-model object may only be entered
  by one thread, the thread that called it.
  However, an object server can support multiple
  objects each being entered simultaneously by
  different threads. Common data held by the object
  server must be protected against thread
  collisions.
• Calls to the object from the apartment thread are
  not marshaled. Requests that are in the same
  session as an apartment model object are handled
  by the thread that created the apartment model
  object.
• Disadvantage of apartment-threaded objects is
  that they cannot be stored in the Application
  object. The only way to create an
  apartment-threaded object with application scope
  is to declare it with an ltOBJECTgt tag. However,
  when this object is used, the Web server will
  lock the application down to a single thread, the
  one that created the object. This will reduce
  server performance significantly, and should only
  be considered for intranet applications.
• In addition, if an apartment-threaded object is
  created with session scope or is stored in the
  Session object, the Web server will lock the
  session down to the single thread that created
  the object.

49
Free-Threaded

• This threading model is not recommended for
  components that will be called by ASP
• Free-threaded objects place no restrictions on
  which threads or how many threads can enter the
  object. The object cannot contain thread-specific
  data and must protect its data from simultaneous
  access by multiple threads.
• The Web server creates free-threaded objects in a
  different thread than the one that called
  CoCreateInstance. All calls to the object are
  marshaled to a free-threading thread.
• One disadvantage of free-threaded objects is that
  they cannot be stored in the Application object.
  The only way to create a free-threaded object
  with application scope is to declare it with an
  ltOBJECTgt tag. However, when this object is used,
  the Web server will lock the application down to
  a single thread, the one that created the object.
  This will reduce server performance
  significantly, and should only be considered for
  intranet applications.
• In addition, if a free-threaded object is created
  with session scope or is stored in the Session
  object, the Web server will lock the session down
  to the single thread that created the object.

50
Both Threaded

• This threading model is highly recommended for
  components that will be called by Active Server
  Pages.
• ActiveX objects marked as both can be used in
  either apartment-threaded or free-threaded modes.
  They can be entered by multiple threads, protect
  their data from thread collisions, and do not
  contain thread-specific data.
• The Web server creates an object marked as both
  in a single thread, the one that serviced the
  request. The call to CoCreateInstance is not
  marshaled to another thread. However, if the
  object has session scope or is placed in the
  Session object, the Web server will not lock the
  session to that thread. Calls to the object from
  other requests in the same session are executed
  in the request thread.
• Because objects marked as both guarantee to
  protect their data against multiple thread
  access, they can be used for objects that have
  application scope.