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ASP Quick Reference

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ASP Quick Reference from w3ii. Print it, and fold it in your pocket.

Basic Syntax

ASP scripts are surrounded by <% and %>.  To write some output to a browser:

<html>
<body>
<% response.write("Hello World!") %>
</body>
</html>

The default language in ASP is VBScript. To use another scripting language, insert a language specification at the top of the ASP page:

<%@ language="javascript" %>
<html>
<body>

<%
....
%>

Forms and User Input

Request.QueryString is used to collect values in a form with method="get". Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and has limits on the amount of information to send.

Request.Form is used to collect values in a form with method="post". Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.

ASP Cookies

A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests for a page with a browser, it will send the cookie too.

The Response.Cookies command is used to create cookies:

<%
Response.Cookies("firstname")="Alex"
Response.Cookies("firstname").Expires="May 10,2002"
%>

Note: The Response.Cookies command must appear BEFORE the <html> tag!

The "Request.Cookies" command is used to retrieve a cookie value:

<%
fname=Request.Cookies("firstname")
response.write("Firstname=" & fname)
%>

Including Files

You can insert the content of one ASP file into another ASP file before the server executes it, with the #include directive. The #include directive is used to create functions, headers, footers, or elements that will be reused on multiple pages

Syntax:

<!--#include virtual="somefile.inc"-->
or
<!--#include file ="somefile.inc"-->

Use the virtual keyword to indicate a path beginning with a virtual directory. If a file named "header.inc" resides in a virtual directory named /html, the following line would insert the contents of "header.inc":

<!-- #include virtual ="/html/header.inc" -->

Use the file keyword to indicate a relative path. A relative path begins with the directory that contains the including file. If you have a file in the html directory, and the file "header.inc" resides in html\headers, the following line would insert "header.inc" in your file:

<!-- #include file ="headers\header.inc" -->

Use the file keyword with the syntax (..\) to include a file from a higher-level directory.

Global.asa

The Global.asa file is an optional file that can contain declarations of objects, variables, and methods that can be accessed by every page in an ASP application.

Note: The Global.asa file must be stored in the root directory of the ASP application, and each application can only have one Global.asa file.

The Global.asa file can contain only the following:

  • Application events
  • Session events
  • <object> declarations 
  • TypeLibrary declarations
  • the #include directive

Application and Session Events

In Global.asa you can tell the application and session objects what to do when the application/session starts and what to do when the application/session ends. The code for this is placed in event handlers. Note: We do not use <% and %>, to insert scripts in the Global.asa file, we have to put the subroutines inside the HTML <script> tag:

<script language="vbscript" runat="server">
sub Application_OnStart
  ' some code
end sub
sub Application_OnEnd
  ' some code
end sub
sub Session_OnStart
  ' some code
end sub
sub Session_OnEnd
  ' some code
end sub
</script>

<object> Declarations

It is also possible to create objects with session or application scope in Global.asa by using the <object> tag. Note: The <object> tag should be outside the <script> tag!

Syntax:

<object runat="server" scope="scope" id="id"
{progid="progID"|classid="classID"}>
.......
</object>

TypeLibrary Declarations

A TypeLibrary is a container for the contents of a DLL file corresponding to a COM object. By including a call to the TypeLibrary in the Global.asa file, the constants of the COM object can be accessed, and errors can be better reported by the ASP code. If your Web application relies on COM objects that have declared data types in type libraries, you can declare the type libraries in Global.asa.

Syntax:

 <!--METADATA TYPE="TypeLib"
file="filename"
uuid="typelibraryuuid"
version="versionnumber"
lcid="localeid"
-->

The Session Object

The Session object is used to store information about, or change settings for a user session. Variables stored in the Session object hold information about one single user, and are available to all pages in one application.

Collections

  • Contents - Holds every item added to the session with script commands
  • StaticObjects - Holds every object added to the session with the <object> tag, and a given session
  • Contents.Remove(item/index) - Deletes an item from the Contents collection
  • Contents.RemoveAll() - Deletes every item from the Contents collection

Properties

  • CodePage - Sets the code page that will be used to display dynamic content
  • LCID - Sets the locale identifier that will be used to display dynamic content
  • SessionID - Returns the session id
  • Timeout - Sets the timeout for the session

Method

  • Abandon - Kills every object in a session object

Application Object

A group of ASP files that work together to perform some purpose is called an application. The Application object in ASP is used to tie these files together. All users share one Application object. The Application object should hold information that will be used by many pages in the application (like database connection information).

Collections

  • Contents - Holds every item added to the application with script commands
  • StaticObjects - Holds every object added to the application with the <object> tag
  • Contents.Remove - Deletes an item from a collection
  • Contents.RemoveAll - Deletes every item from a collection

Methods

  • Lock - Prevents a user from changing the application object properties
  • Unlock - Allows a user to change the application object properties

The Response Object

The Response Object is used to send output to the user from the server.

Collection

  • Cookies(name) - Sets a cookie value. If the cookie does not exist, it will be created, and take the value that is specified

Properties

  • Buffer - Whether to buffer the output or not. When the output is buffered, the server will hold back the response until all of the server scripts have been processed, or until the script calls the Flush or End method. If this property is set, it should be before the <html> tag in the ASP file
  • CacheControl - Sets whether proxy servers can cache the output or not. When set to Public, the output can be cached by a proxy server
  • Charset(charset_name) - Sets the name of the character set (like "ISO8859-1") to the content type header
  • ContentType - Sets the HTTP content type (like "text/html", "image/gif", "image/jpeg", "text/plain"). Default is "text/html"
  • Expires - Sets how long a page will be cached on a browser before it expires
  • ExpiresAbsolute - Sets a date and time when a page cached on a browser will expire
  • IsClientConnected - Checks if the client is still connected to the server
  • Pics(pics_label) - Adds a value to the pics label response header
  • Status - Specifies the value of the status line

Methods

  • AddHeader(name, value) - Adds an HTML header with a specified value
  • AppendToLog string - Adds a string to the end of the server log entry
  • BinaryWrite(data_to_write) - Writes the given information without any character-set conversion
  • Clear - Clears the buffered output. Use this method to handle errors. If Response.Buffer is not set to true, this method will cause a run-time error
  • End - Stops processing the script, and return the current result
  • Flush - Sends buffered output immediately. If Response.Buffer is not set to true, this method will cause a run-time error
  • Redirect(url) - Redirects the user to another url
  • Write(data_to_write) - Writes a text to the user

Request Object

When a browser asks for a page from a server, it is called a request. The Request Object is used to get information from the user.

Collection

  • ClientCertificate - Holds field values stored in the client certificate
  • Cookies(name) - Holds cookie values
  • Form(element_name) - Holds form (input) values. The form must use the post method
  • QueryString(variable_name) - Holds variable values in the query string
  • ServerVariables(server_variable) - Holds server variable values

Property

  • TotalBytes - Holds the total number of bytes the client is sending in the body of the request

Method

  • BinaryRead - Fetches the data that is sent to the server from the client as part of a post request

Server Object

The Server Object is used to access properties and methods on the server.

Property

  • ScriptTimeout - Sets how long a script can run before it is terminated

Method

  • CreateObject(type_of_object) - Creates an instance of an object
  • Execute(path) - Executes an ASP file from inside another ASP file. After executing the called ASP file, the control is returned to the original ASP file
  • GetLastError() - Returns an ASPError object that will describe the error that occurred
  • HTMLEncode(string) - Applies HTML encoding to a string
  • MapPath(path) - Maps a relative or virtual path to a physical path
  • Transfer(path) - Sends all of the state information to another ASP file for processing. After the transfer, procedural control is not returned to the original ASP file
  • URLEncode(string) - Applies URL encoding rules to a string

Source : http://www.w3ii.com/asp/asp_quickref.asp


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