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Content
Introduction Server Side Programming (ASP) Database Integration
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Introduction Internet allows for client-server systems Programs can be invoked on either/both
clients and servers:– Client side includes Java Applets, ActiveX
components with JScript or VBScript.– Server side includes CGI and ASP
Data can be kept on servers distributed across network and accessed via client (topic of this portion of course)
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Why use Internet to access data? People can access the data using a familiar
browser interface. No special software required.
Data can be maintained centrally or distributed.
Data can be integrated with other information in an institution’s web pages
Information can be made available to anyone (with permission) on the Internet
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How can database be accessed by web browser?
Web browser Web browser
Web browser
Server Side Programminge.g. Microsoft IIS server :
ASP (VBScript, JScript, SQL)
Internet
Database
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Client Side Scripts They are browser-specific, so the same code may
be interpreted differently depending on the browser being used. (Note recent use of ECMAScript as general JScript or JavaScript)
They can't be used to refer to a database (such as a product catalog).
They can lessen the burden on server and are particularly useful for such tasks as validating data before sending to server side to be processed.
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Content
Server Side programming overview Example
– Microsoft Internet Information Services (IIS)– Active Server Page(ASP)– VBScript/JScript
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Common Gateway Interface (CGI) CGI Is a standard for interfacing
external applications with web servers (Common Gateway Interface, 1995).
Involves a new process each time it is invoked therefore can be slow with multiple users.
Alternatives: ISAPI (ASP), NSAPI.
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IIS
IIS is a web server that runs on Win NT, 2000, Server2003 and XP Server.
Can use component-based (COM/ActiveX) client/server applications as well as JScript (ECMAScript) and VBScript
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What is ASP?
"a server - side scripting environment that you can use to create and run dynamic, interactive, high - performance Web server applications”. Microsoft
Can include COM/ActiveX components and/or compiled code
Runs on IIS
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What are Active Server Pages?
Server-side environment Can provide compile-free application
environment Combine HTML, scripts, COM and
ActiveX server components.
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Using ASP User usually completes HTML form in a browser
and submits this to a .asp file on the server (note that you need a .asp file on the server)
.asp file contains both HTML and scripts/components
Scripts/components invoked and produce new HTML code
resulting page: original HTML + new HTML (generated by asp) - this is sent to client.
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Using ASP Server evaluates tag starting with <% and
ending with %> Scripts/components contained within tags Web servers supporting ASP:
– Personal Web Server (Windows 95, 98, NT)– Internet Information Services (Windows NT
Server, 2000 Server, Server 2003, XP)
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ASP Application Dell Computers
– http://www.dell.com Barnes and Noble Book Store
– http://www.bn.com Pricescan
– http://www.pricescan.com
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ASP Basics
ASP file is a text file with the extension .asp
it contains any combination of:– Text– HTML Tags– ASP Script Commands/Components
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ASP Script ASP Script could be VBScript or Jscript
(ECMAScript) A script is a series of commands or
instructions. Script command instructs the web server
to perform an action. VBScript is similar to Visual Basic and
Visual Basic for Application (VBA).
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VBScript Basics Not case sensitive Declaring Variables
VBScript does not require variable declarations, but it is good scripting practice to declare all variables before using them. To declare a variable in VBScript, use the Dim, Public, or Private statement.
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Declaring VariablesDim: Declares variables and allocates storage space. Variables
declared with Dim at the script level are available to all procedures within the script. At the procedure level, variables are available only within the procedure. Ex. Dim A,B
Private: Used at script level to declare private variables and allocate storage space. Private variables are available only to the script in which they are declared
Public: Used at script level to declare public variables and allocate storage space. Variables declared using the Public statement are available to all procedures in all scripts in all projects.
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VBScript Basics
VBScript Operators:– Arithmetic: +, -, *, /, ^– Comparison: =, <>, <, >, <=, >=– Logical (for Boolean variables): Not, And,
Or, Xor
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VBScript Basics
Conditional Statement:– IF … Then… Else
• If condition Then [Statement]• elseif condition-n Then [elseifstatment]…• else [elsestatements]• End if
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VBScript Basics Loop:
– Do … Loop– While …Wend– For … Next– For Each …Next
Procedures:– Sub– Function
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ASP Demo ASP uses <% and %> to enclose script commands.
<html><head><title>ASP Example 1</title></head><body> <p>This page was last refreshed on <%= Date %> </p> <p>Now it is <%= Now %> </p></body></html>
Note 1: The VBScript function Now returns the current time, Date returns current date.
Note 2: No data is input by the user
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Running ASP
Save file with .asp extension on server Client accesses the file in similar
fashion to .htm (or .html) file Server detects .asp extension and runs
script within ASP tags Results sent to clienthttp://128.255.21.191/Example1/Example1.asp
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Client-Server Structure
IIS
Client
request
Running ASPScript...
results
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Example 2 <html> <head><title>ASP Example 2</title></head> <body> <form method="POST" action="resultofexample2.asp"><p>A= <input type="text" name="ValueofA" size="20"></p><p>B= <input type="text" name="ValueofB" size="20"></p><p><input type="submit" value="Calculate" name="B1"></p></form></body></html>
http://128.255.21.191/Example2/Example2.htm
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Example 2 see web siteContained in HTML code:
<%@ language="vbscript" %>
<% dim A, B
A=Request.form("ValueofA")
B=Request.form("ValueofB")
%>
……….
<p>A+B= <%= eval(A)+eval(B) %> </p>
<p>A-B= <%= eval(A)-eval(B) %> </p>
<p>A*B= <%= eval(A)*eval(B) %> </p>
…….
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example 2 asp
<html> <head><title>Example 2 ASP Page</title></head> <body> <p>Example Page <%@ language="vbscript" %> <% dim A, BA=Request.form("ValueofA")B=Request.form("ValueofB") %> </p> <p>A+B= <%= eval(A)+eval(B) %> </p> <p>A-B= <%= eval(A)-eval(B) %> </p> <p>A*B= <%= eval(A)*eval(B) %> </p></body></html>
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What is a Database? A database is an organized collection of
related data, typically stored on disk, and accessible by possibly many concurrent users.
Most common is relational database, which is a tabular database in which the data is defined so that it can reorganized and accessed in a number of different ways
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Database Management Systems DBMS A program to access, manipulate and present
the data to a user. Example DBMS:
– Oracle– Sybase (Microsoft SQL)– IBM’s DB2, IMS and SQL/DS– dBase– Access
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Relational Database Structure
set of tables containing data fitted into predefined categories.
each table(relation) contains one or more data categories in columns.
each row contains a unique instance of data for the categories defined by column.
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Relationships in Access
Multiple tables in one database Matching key fields between table
– A key is usually a field with the same name in both tables.
– Such key is primary key for one table, foreign key in the other table.
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SQL SQL: Structured Query Language It is used to query from and update
database. Systems using SQL:
• Oracle• Sybase• Microsoft SQL server• Access
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SQL Exampledatabase - example3.mdbtablename - table1columnname - ID, ItemName, Price
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SQL Example To find out the ‘Price’ when ‘ItemName’
equals to Candy
SELECT Price FROM Table1 WHERE ItemName = ‘Candy’
Note:
Can SELECT * to return whole row as an object - see Example 3 on website
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SQL Basic
Insert tablename (fieldname1, fieldname2…)
values (value1, value2)
update tablename
set column_name1=expression1
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SQL Basic
Create tablename (fieldname1 type, fieldname2 type)
Delete [*] from tablename where clause (deletes whole row)
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Database Integration Requirements
Server (IIS) Database
• Internet database connector (ODBC) not always required can use ADODB
Dynamic Web Page (asp)• User Input using HTML forms• Data Transmission• Retrieving data from database• Display results
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Using web browser to access a database Web pages and forms are used to
provide access to the database. Database can be queried or updated. Platform-independent front-end. Database vendor-independent front-end Client machine does not need database
networking software
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Example Implementation
Step 1: HTML file (containing forms) for user input on server.
Step 2: Database on server Step 3: Setup database connection
(ODBC)
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Step I: HTML File with Forms Example:<form method="Post" action="Find.asp">
<p> <select name = "item" method ="post" size ="1"><option selected value="Gum">Gum</option><option selected value="Suckers">Suckers</option><option selected value="Taffy">Taffy</option><option selected value="Skittles">Skittles</option><option selected value="M&Ms">M&Ms</option><option selected value="Lifesavers">Lifesavers</option><option selected value="Snickers">Snickers</option></select><input type="submit" value="Tell me the price"></p></form>
This captures user input and sends result to result.asp
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Step II: Database
Under the home directory, create the access database named “Candy.mdb”
tablename - Products columnname - ID, ItemName, Price
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<%@ LANGUAGE='VBSCRIPT'%><html><head></head><body><%dim priceSet MyConn = Server.CreateObject("ADODB.Connection")set rs = Server.CreateObject("ADODB.Recordset")MyConn.Open "DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=" & Server.MapPath("Candy.mdb")item = Request.form("item")Set RS = MyConn.execute("Select * from Products where Candy = '" & item & "'")
if rs.Eof thenPrice = ""elsePrice = RS("Price")End ifResponse.Write("It will cost you $" & price)
Set MyConn = nothingSet rs = nothing
%></body></html>
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Running ASP
Check the extension (asp) server evaluates tag starting with <%
and ending with %> server replaces the tags with normal
HTML using scripts results page: original Markup + new
Markup(generated by asp)