Basics of Web database

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Basics of Web database

• With the advent of Web database technology, Web
  pages are no longer static, but dynamic with
  connection to a back-end database.
• Web sites are now able to display updated
  information on-the-fly and support user
  interactivity.
• One can use the same page to display information
  of thousands of products in a database.

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Three tiers of Web database

• To build a Web database, usually we need to use
  a three-tier model
• Web server
• Web application server (middleware), and
• Database

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How a user interacts with a Web database

• From a Web browser, a user submits a request to
  the Web server.
• The Web server passes it onto the middleware
• The middleware writes the request in SQL queries
  and sends it to a back-end database.
• The data retrieved are handed back to the
  middleware

4
How a user interacts with a Web database

• 5. The middleware generates a Web page for the
  data
• 6. The Web server sends the Web page to the
  browser
• 7. The browser displays the Web page to the user
  

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Web database connectivity

• Web-database connectivity takes several different
  forms
• CGI scripting A custom application is developed
  using a traditional programming language (such as
  C, Python, Perl, or Java) accessed through the
  Common Gateway Interface (CGI).
• Application server Such as ColdFusion or ASP,
  which works with the Web server that can
  communicate with databases through ODBC

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ASP Middleware for Windows platform

• ASP stands for Active Server Pages
• ASP is a programming environment that gives the
  ability to generate dynamic html pages with the
  help of server side scripting.
• VBScript is the default scripting language for
  ASP

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ASP Middleware for Windows platform

• An ASP page is almost the same as a HTM or HTML
  page... the only difference is that an ASP page
  has the '.asp' extension
• Active Server Page can include both client side
  and server side scripts.
• In an ASP page VBScript is usually used as the
  server side and Java Script as the client side
  scripting language

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Special software needed to write ASP?

• You don't need any special software to write an
  ASP page.
• An ASP page can be written with any HTML
  editor... even in Windows Notepad.
• If you are looking for some special software to
  write an ASP page, Microsoft Visual InterDev is
  the best tool for you.

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Special software needed to write ASP?

• InterDev helps you to easily develop ASP
  applications because it simplifies the process of
  developing and debugging ASP applications
• ASP is browser independent because all the
  scripting code runs on the server and the browser
  only gets a normal HTML page as a result of
  server side scripting.

10
ASP compatibility

• ASP is an engine/program built into Internet
  Information Server (IIS) / Personal Web Server
  (PWS)
• PWS is a smaller - but fully functional - version
  of IIS
• To run IIS you must have Windows NT 4.0 or later
• To run PWS you must have Windows 95 or later

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What is an ASP file?

• An ASP file is just the same as an HTML file
• An ASP file can contain text, HTML, XML, and
  scripts
• Scripts in an ASP file are executed on the server
  
• An ASP file has the file extension .asp

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How does it work?

• When a browser requests an HTML file, the server
  returns the file
• When a browser requests an ASP file, IIS/ PWS
  passes the request to the ASP engine
• The ASP engine reads the ASP file, line by line,
  and executes the scripts in the file
• Finally, the ASP file is returned to the browser
  as plain HTML

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What can be done with ASP

• Dynamically edit, change or add any content of a
  Web page
• Respond to user queries or data submitted from
  HTML forms
• Access any data or databases and return the
  results to a browser

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What can be done with ASP

• The advantages of using ASP instead of CGI and
  Perl, are those of simplicity and speed
• Provides security since your ASP code can not be
  viewed from the browser
• Since ASP files are returned as plain HTML, they
  can be viewed in any browser

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A sample ASP script

• ltHTMLgt
• ltHEADgt ltTITLEgtHello Worldlt/TITLEgt
• lt/HEADgtltBODYgt
• lt
• ' This will print to the browser the 
• ' words Hello, ASP World.
• response.write "Hello, ASP World!"
• gt
• lt/BODYgtlt/HTMLgt

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ASP and database server

• To interact with a database, you usually have to
  add code that talks to a particular database
  using a proprietary language.
• If you want your program to talk to an Access,
  FoxPro and Oracle databases you have to code your
  program with three different database languages.

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ASP and database server

• When programming to interact with ODBC you only
  need to talk the ODBC language.
• The ODBC Manager will figure out how to contend
  with the type of database you are targeting
• All that you need to do is have installed an ODBC
  driver that is specific to the type of database
  you will be using.

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ODBC/DSN

• ODBC stands for Open Database Connection (or
  Connectivity). 
• ODBC makes it easy to create ASP scripts that
  will connect to a database. 
• Normally, each ODBC will have a DSN (Data Source
  Name). 
• DSN contains all the information about the
  database

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Setting up the DSN

• Setting up the DSN is a simple process.
• Simply double-click the ODBC in the Control Panel
• Choose the System DSN tab, and click Add. Choose
  the type of database you'll be working with - the
  sample database is MS Access - then click finish.
  
• You'll then need to type in the database name in
  the Data Source Name box, and click Select.

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Setting up the DSN

• Next you'll navigate to the drive and directory
  where the database is located,
• Click on the file name and click OK on that
  window and the one behind it.
• Now you can refer to the database by name in your
  scripts and the system will know which ODBC
  driver to use and where the database is located.

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Online ASP Tutorials

• http//www.vallin.com/pub/1/asp1.asp
• http//www.4guysfromrolla.com/
• http//www.15seconds.com/
• http//www.learnasp.com/
• http//msdn.microsoft.com/library/default.asp?URL
  /library/en-us/dnasp/html/asptutorial.asp