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ASP/ASP.NET: Tricks and Tips
How to get Microsoft’s Programming Language to work for you
By Wade Tripp
Park University
DisclaimerI am not an expert in all the details, just
giving a general overview of how it works, and there are over a dozen ways how to do things, with half of them working.
Who are YOU?
History of ASP (abbreviated)
• VBScript– Client Side– Possible for all sorts of problems,
intentional or not– Required the client to have IE installed
History of ASP (abbreviated)
• ASP– Server Side Scripting– Browser independent– Required special server software
• but…..– Very much interpreted and scripting– Created many bad programming
habits
History of ASP (abbreviated)
• ASP.NET– Server Side Scripting– Able to program in many languages– Permits good programming practice
• but….– Steep learning curve
How ASP works
• Browser requests a web page
• Web server gets request and loads file from hard drive
• Web server sends the file to asp.dll to process
• Returns to the browser the processed page
How ASP.NET works (interpreted)
• Browser requests a web page
• Web server gets request and loads the file from hard drive
• Web server sends the file to aspnet_isapi.dll to process
• Returns to the browser the processed page
How ASP.NET works (compiled)
• Browser requests a web page
• Web server gets request and loads dll from hard drive
• Web server sends the file to aspnet_isapi.dll to process
• Returns to the browser the processed page
• The code does not have to be on the server
Differences between ASP
ASP
Quick and easy to use and do
Easy to modify and tweak
Uses the very basics and forgiving
ASP.NET(Interpreted)
Increased flexibility
No need to code everything from scratch
Memory of events
Still can get confusing for large projects
ASP.NET(Compiled)
Most flexible
Hardest to understand
Easy to get good programming standards
Differences between ASP
Simple and quick – ASP
Ex – Date modified, Alert Message
Repeated on several pages – ASP.NET Interpreted
Ex – Announcement on several web pages
Advanced Application – ASP.NET Compiled
Ex – Registration form
Getting down to codeASP/ASP.NET handles the appearance,
input/output of a web page
The Code Behind focuses on the thinking and language
“Code Behind” can happen in a web page itself and does not have to be in a .vb or .cs file
Any language can use in theory, VB and C# are the ones Microsoft has preconnected in Visual Studio, but almost any can be used. Java is not used for various legal reasons.
Simple Displaying StuffTo simply display stuff ( traditionally used in
ASP ) you use <% %>
<% Response.Write ("Hello World") %>
<% = 2 + 2 %>
ASP is forgiving, so if you miss the ( ) in Response.Write, it has variant type and other items. But if you save it as .aspx it may not work.
Is .asp the same as .aspxNo, but they are so close that most of the time
you can just do minor changes and tweaks going from asp to aspx . Several things are required (Declaration of variables)
The big change with CDONTS. The method for sending out mail was changed from ASP to ASP.NET IIS 5 to IIS 6 for various reasons [Security being the main one]
QueryString vs. FormsThere are two ways to get information.• QueryString/Get
– Information is sent via the URL
• Form/Post– Information sent in the page
QueryString<form method="GET">
It appears in the URL
.. /index.asp?Sample=test&B1=Submit
The ? Marks the end of the URL and the rest are variables
Items are recoded for valid characters (make spaces into +, & turned into %26 and other items)
Advantage jump directly to section, performing items
QueryString DisadvantagesEasily find the information via History and
guessable test.asp?ID=45
Limited on how much information can be passed. Dependant on browser of 1000, 2000+ characters
FormWhat is normally used with web pages
<form method="POST">
Better to make things go better and organized, less chance of being reviewed
Actually using it<%
Dim intNumber as integer
intNumber = Request.QueryString(“Test”)
intNumber = Request.Form(“Test”)
Response.Write (intNumber)
%>
TIP - Polish NotationBased on ideas of Jan Lukasiewicz
Standard documenting is putting type in front of name
• intName – Integer• strName – String• bolName – Boolean values
TIP - Polish NotationAlso good for ASP• txtName – Textbox• lblName – Label• panName – Panel• lstName – List
….
It keeps you organized
Basics of ASP.Net <asp:TextBox id="TextBox1"
runat="server"></asp:TextBox>
When it is transformed by the compiler it becomes
<input name="TextBox1" type="text" id="TextBox1" />
What all happened?
ASP.NET is transformed into HTML
How does information get storedInformation is stored in a hidden view, called
the Viewstate
It sends and organizes the information for each variable and items
<input type="hidden" name="__VIEWSTATE" value="dDwxMKA0NDg0NTY3Ozs+LbpQGFDDxjwkOEzOioQydd7xkTg=" />
The information is stored for all server objects
TIP – Don’t make everything label
Each ASP.NET item requires resources
Don’t use labels for standard items.
Why?
Because it takes extra resources and time to download
TIP – Don’t make everything label
Each ASP.NET item requires resources
Don’t use labels for standard items.
Why?
Because it takes extra resources and time to download
TRICKS – Storing informationInformation can be handled• Session• Application• Variable• Value of ASP Object• Hidden Field• Passed Variable in Form
TRICKS – Database ReadingCan connect to database via connection with
SQL, Access, Informix, etc… anything that permits ODBC
Warning – Access can cause problems with older web servers
TRICKS – AutoPostbackPermits scripting to run after an item has been
altered
Requires Javascript
TRICKS – ValidationLets a user check to make sure a field is
probably filled out
Normally uses Javascript to validate
There are a few ways around it (disable Javascript)
TRICKS – Smart NavigationPermits forms not to blink by using ‘IFRAME’
TRICKS – ME - ASPUsed to find what variables and objects are
used
Remove the Me. after you go though the form
