ASP AJAX
What Is AJAX?
AJAX = Asynchronous JavaScript and XML.
AJAX is a technique for creating fast and dynamic web pages.
AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.
Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.
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How AJAX Works
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AJAX Is Based On Internet Standards
AJAX is based on internet standards, and uses a combination of:
- XMLHttpRequest object (to exchange data asynchronously with a server)
- JavaScript/DOM (to display/interact with the information)
- CSS (to style the data)
- XML (often used as the format for transferring data)
AJAX applications are browser- and platform-independent!
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Google Suggest
AJAX was made popular in 2005 by Google, with Google Suggest. It is using AJAX to create a very dynamic web interface: When you start typing in Google's search box, a JavaScript sends the letters off to a server and the server returns a list of suggestions.
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The ASP File
The page on the server called by the JavaScript above is an ASP file called "getcustomer.asp".
The source code in "getcustomer.asp" runs a query against a database, and returns the result in an HTML table:
response.expires=-1
sql="SELECT * FROM CUSTOMERS WHERE CUSTOMERID="
sql=sql & "'" & request.querystring("q") & "'"
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open(Server.Mappath("/datafolder/northwind.mdb"))
set rs=Server.CreateObject("ADODB.recordset")
rs.Open sql,conn
response.write("<table>")
do until rs.EOF
for each x in rs.Fields
response.write("<tr><td><b>" & x.name & "</b></td>")
response.write("<td>" & x.value & "</td></tr>")
next
rs.MoveNext
loop
response.write("</table>")
%>
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