Getting Data Without Refreshing Page

[Andy]

Hi,

Does anybody know if it is possible to retrieve data from a database and
update to the page without actually refreshing the whole page?

As an example, say I have 10,000 people's name from the database listed in
a drop down combo box. I select a person from the drop down list, for which
I then use some script to put that persons age into a text field.

My problem is that I have bandwidth limits (10,000 people's names, Ahhhh),
and so the solution is to enter the person’s name, and send this to the server
to let SQL Server get the age. But the only method I know how is to reload
the whole page again.

Is there a method of executing some client script, which calls some server
script, which in turn passes data back to the client script, which can then
be populated into fields on the page?

I welcome any ideas, suggestions, solutions.

Thanks

[Sachin]

do something like this:-
'client side script:-
var i = <%= SomeASPFunction()%>;

'server side
Function SomeASPFunction()
'
'
'
SomeASPFunction = result
End Function

with this method its easy to get one or two values from the server side...if
you more values you can try returning back an array ( I have'nt tried that
myself ) :-)
Sachin

"Andy" <andy_boyd@yahoo.co.uk> wrote in message
news:3b5d27cd$1@news.devx.com...
>
> Hi,
>
> Does anybody know if it is possible to retrieve data from a database and
> update to the page without actually refreshing the whole page?
>
> As an example, say I have 10,000 people's name from the database listed in
> a drop down combo box. I select a person from the drop down list, for
which
> I then use some script to put that persons age into a text field.
>
> My problem is that I have bandwidth limits (10,000 people's names, Ahhhh),
> and so the solution is to enter the person's name, and send this to the
server
> to let SQL Server get the age. But the only method I know how is to
reload
> the whole page again.
>
> Is there a method of executing some client script, which calls some server
> script, which in turn passes data back to the client script, which can
then
> be populated into fields on the page?
>
> I welcome any ideas, suggestions, solutions.
>
> Thanks
>

[Harish Kumar]

Hello Andy,

You can use client pull technology in this case. The concept behind this
is pretty simple. At regular intervals of time, the web page will connect
and dynamically pull updated data from the web server. You should specify
the time intervals and the URL to connect to like this -

<meta http-equiv="refresh" content="10; URL="http://mywebserver.com/clientpull.asp">

HTH,
Harish
"Andy" <andy_boyd@yahoo.co.uk> wrote:
>
>Hi,
>
>Does anybody know if it is possible to retrieve data from a database and
>update to the page without actually refreshing the whole page?
>
>As an example, say I have 10,000 people's name from the database listed
in
>a drop down combo box. I select a person from the drop down list, for which
>I then use some script to put that persons age into a text field.
>
>My problem is that I have bandwidth limits (10,000 people's names, Ahhhh),
>and so the solution is to enter the person’s name, and send this to the
server
>to let SQL Server get the age. But the only method I know how is to reload
>the whole page again.
>
>Is there a method of executing some client script, which calls some server
>script, which in turn passes data back to the client script, which can then
>be populated into fields on the page?
>
>I welcome any ideas, suggestions, solutions.
>
>Thanks
>

[Matthew Solnit]

"Andy" <andy_boyd@yahoo.co.uk> wrote in message news:3b5d27cd$1@news.devx.com...
> As an example, say I have 10,000 people's name from the database listed in
> a drop down combo box. I select a person from the drop down list, for which
> I then use some script to put that persons age into a text field.

You can store the person's age in the VALUE attribute of the OPTION element.
Then write a client-side script that handles the onchange() event and displays
the age of the selected person.

-- Matthew Solnit

[Russell Jones]

Use remote scripting or (with IE-only clients) the XMLHTTPRequest object to
make background queries to the server that post and retrieve data without
refreshing the page. These techniques are not only relatively easy to
implement, but will change the way you design your applications.


"Andy" <andy_boyd@yahoo.co.uk> wrote in message
news:3b5d27cd$1@news.devx.com...
>
> Hi,
>
> Does anybody know if it is possible to retrieve data from a database and
> update to the page without actually refreshing the whole page?
>
> As an example, say I have 10,000 people's name from the database listed in
> a drop down combo box. I select a person from the drop down list, for
which
> I then use some script to put that persons age into a text field.
>
> My problem is that I have bandwidth limits (10,000 people's names, Ahhhh),
> and so the solution is to enter the person's name, and send this to the
server
> to let SQL Server get the age. But the only method I know how is to
reload
> the whole page again.
>
> Is there a method of executing some client script, which calls some server
> script, which in turn passes data back to the client script, which can
then
> be populated into fields on the page?
>
> I welcome any ideas, suggestions, solutions.
>
> Thanks
>

[Brian Barnett]

"Russell Jones" <arj1@northstate.net> wrote:
>Use remote scripting or (with IE-only clients) the XMLHTTPRequest object
to
>make background queries to the server that post and retrieve data without
>refreshing the page. These techniques are not only relatively easy to
>implement, but will change the way you design your applications.
>
>
>"Andy" <andy_boyd@yahoo.co.uk> wrote in message
>news:3b5d27cd$1@news.devx.com...
>>
>> Hi,
>>
>> Does anybody know if it is possible to retrieve data from a database and
>> update to the page without actually refreshing the whole page?
>>
>> As an example, say I have 10,000 people's name from the database listed
in
>> a drop down combo box. I select a person from the drop down list, for
>which
>> I then use some script to put that persons age into a text field.
>>
>> My problem is that I have bandwidth limits (10,000 people's names, Ahhhh),
>> and so the solution is to enter the person's name, and send this to the
>server
>> to let SQL Server get the age. But the only method I know how is to
>reload
>> the whole page again.
>>
>> Is there a method of executing some client script, which calls some server
>> script, which in turn passes data back to the client script, which can
>then
>> be populated into fields on the page?
>>
>> I welcome any ideas, suggestions, solutions.
>>
>> Thanks
>>
>
>
I've used Remote Scripting and that works great if your browser (IE or Netscape)
is on Windows. If your clients will potentially be on a Mac then you can't
use Remote Scripting (if someone knows how to do it on a Mac please let me
know).

I have a similar situation in that I have a page with two drop down lists.
The client environment is a mix of Windows and Mac, IE and Netscape.

The first list contains a small number of elements (approx. 57). The second
drop down list needs to be filtered based on the selection in the first list.
A technique I'm thinking about is this:
When the user selects an item from list one I call a client-side JS function
that opens a tiny browser child window, loading another ASP to retrieve the
data from the database, filtered on the ID of the item selected in list one.
Once the data is retrieved my child ASP will generate client-side JS to
populate the second list on the parent window, since the child window has
a reference to it's parent window and thus a reference to the controls on
the page.

This is still theory and I have not tried it out yet. I hope to be able
to try it out in the next couple of weeks on the app I'm developing.

Thanks

[Scott Bockelman]

Andy,

I have done this using various techniques in several production applications
running successfully now for 2+ years.

The best way, in my opinion, is to use a Java Applet and LiveConnect (JavaScripting
of Java Applets). It does work in both IE and Netscape.

I cannot, obviously publish any source code here, but I can point you in
the right direction.

You want to end up with an applet on the page that is sized to 1x1 pixels,
so it is practically invisible and that exposes at least 1, possibly 2, public
methods for getting information from a remote URL.

I suggest methods such as String getURLContent( sURL, sBaseURL, bIgnoreCache
) and Enumeration getURLLines( sURL, sBaseURL, bIgnoreCache ).

Your client-side JavaScript can call these methods like so:

var newContent = document.applets['myAppletName'].getURLContent( "../include/getOptionsByKey.asp?key=x",
document.URL, true );

In the Java implementation of these methods, you need to create the following
objects, java.net.URL and java.io.BufferedReader.

You'd do something like this:

StringBuffer buf = new StringBuffer();
URL baseURL = getDocumentBase();
URL url = new URL( baseURL, theURL );
URLConnection conn = url.openConnection();
conn.setUseCaches(false);
conn.connect();
br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ( ( inputLine = br.readLine() ) != null ) {
buf.append(inputLine).append("\n");
}
br.close();
return buf.toString();

Now all you need is an ASP page whose url you can pass to the applet method
that will return some string you can do something with, like use to populate
a drop down list or a text box with a user's age, or whatnot.

P.S. I'd suggest you not start off with a select box with 20,000 names in
it. How about using this same technique to have the user first choose some
category (even if just the first letter of the name) that returns a subset
of that list.

I hope this helps.

Scott Bockelman
Vertek Corporation





"Andy" <andy_boyd@yahoo.co.uk> wrote:
>
>Hi,
>
>Does anybody know if it is possible to retrieve data from a database and
>update to the page without actually refreshing the whole page?
>
>As an example, say I have 10,000 people's name from the database listed
in
>a drop down combo box. I select a person from the drop down list, for which
>I then use some script to put that persons age into a text field.
>
>My problem is that I have bandwidth limits (10,000 people's names, Ahhhh),
>and so the solution is to enter the person’s name, and send this to the
server
>to let SQL Server get the age. But the only method I know how is to reload
>the whole page again.
>
>Is there a method of executing some client script, which calls some server
>script, which in turn passes data back to the client script, which can then
>be populated into fields on the page?
>
>I welcome any ideas, suggestions, solutions.
>
>Thanks
>

[Fred]

I would use <META HTTP-EQUIV="REFRESH" CONTENT="5;pageName.asp"> tag in the
<head> section, created dynamicly based on the data returned!

[rao]

I don't think it is possible. May be possible if you use client record sets
with RDS controls , personally i have not tried it .
"Andy" <andy_boyd@yahoo.co.uk> wrote:
>
>Hi,
>
>Does anybody know if it is possible to retrieve data from a database and
>update to the page without actually refreshing the whole page?
>
>As an example, say I have 10,000 people's name from the database listed
in
>a drop down combo box. I select a person from the drop down list, for which
>I then use some script to put that persons age into a text field.
>
>My problem is that I have bandwidth limits (10,000 people's names, Ahhhh),
>and so the solution is to enter the person’s name, and send this to the
server
>to let SQL Server get the age. But the only method I know how is to reload
>the whole page again.
>
>Is there a method of executing some client script, which calls some server
>script, which in turn passes data back to the client script, which can then
>be populated into fields on the page?
>
>I welcome any ideas, suggestions, solutions.
>
>Thanks
>

[Tushar]

I read all the answers here. I am using the xmlhttp object to do background
requests. I thinks this is the simplest and fastest solution among the one's
supplied. Also, one of the best things is until the data is actually retrieved
the user can continue seeing the page and the new data appears so silently
that the user may think he didn't see it for the first time.

Implement this method it is simple, fast and made for xml, should you decide
to move to xml later. I have already done. That is why.

Tushar