how do I refresh data every x seconds...

[John Butler]

I have a market data application which needs to show live price updates in a
table. This table will refresh every 10-15 seconds. The table is read-only.

Currently, in ASP, I refresh the frame itself, which works fine. However, I
now need to highlight a changed price, as it happens, using some kind of
highlight-fade DHTML sequence..

Hunting around, there seem to be two ways to do this:
1. Use a Web service behaviour
2. Use DotNet remoting

Has anyone grappled with live data refreshes yet? So much of the
documentation assumes there will always be some kind of user response (push
a "refresh" button, edit a record etc)...there isn't a lot on what the
_best_ way to do dynamically refresh a dataset is...without any interaction
and using a timer or something....

Any help appreciated
Regards
John Butler

[Hari]

<META HTTP-EQUIV="REFRESH" CONTENT=15> - This meta tag will send the request
to the server in every 15 sec. Hope this will help you!

- Hari


"John Butler" <nospamjrbutler@btinternet.com> wrote:
>I have a market data application which needs to show live price updates
in a
>table. This table will refresh every 10-15 seconds. The table is read-only.
>
>Currently, in ASP, I refresh the frame itself, which works fine. However,
I
>now need to highlight a changed price, as it happens, using some kind of
>highlight-fade DHTML sequence..
>
>Hunting around, there seem to be two ways to do this:
>1. Use a Web service behaviour
>2. Use DotNet remoting
>
>Has anyone grappled with live data refreshes yet? So much of the
>documentation assumes there will always be some kind of user response (push
>a "refresh" button, edit a record etc)...there isn't a lot on what the
>_best_ way to do dynamically refresh a dataset is...without any interaction
>and using a timer or something....
>
>Any help appreciated
>Regards
>John Butler
>
>
>

[John Butler]

"Hari" <v_hari@indya.com> wrote in message news:3c57bbc5$1@10.1.10.29...
>
> <META HTTP-EQUIV="REFRESH" CONTENT=15> - This meta tag will send the
request
> to the server in every 15 sec. Hope this will help you!
>
> - Hari

Thanks but I am already doing it that way...I'm looking for a better way....

Obviously not many people have wrestled with displaying (constantly
changing) data in a browser with DotNet yet....<sigh>

[David Rothgery]

"John Butler" <nospamjrbutler@btinternet.com> wrote in message
news:3c59c28e@10.1.10.29...
>
> "Hari" <v_hari@indya.com> wrote in message news:3c57bbc5$1@10.1.10.29...
> >
> > <META HTTP-EQUIV="REFRESH" CONTENT=15> - This meta tag will send the
> request
> > to the server in every 15 sec. Hope this will help you!
> >
> > - Hari
>
> Thanks but I am already doing it that way...I'm looking for a better
way....
>
> Obviously not many people have wrestled with displaying (constantly
> changing) data in a browser with DotNet yet....<sigh>

It's more that there really isn't a good solution to that problem.


--
Dave Rothgery
david_rothgery@stratagene.com

[John Butler]

"David Rothgery" <drothgery@alum.wpi.edu> wrote in message
news:3c59cdd9$1@10.1.10.29...
>
> It's more that there really isn't a good solution to that problem.

Guess you're right. I will probably go with the web services behaviour
method and see how far it takes me...

[Jesper Gjedde]

Look into remote scripting.
Brent Ashley have made an example of how to make a VERY lightweight Remote
Scripting based on ASP.
I have used it for an application, that refreshes a table every second using
this and DHTML.

http://www.ashleyit.com/rs/main.htm

Regards

Jesper

"John Butler" <nospamjrbutler@btinternet.com> wrote:
>I have a market data application which needs to show live price updates
in a
>table. This table will refresh every 10-15 seconds. The table is read-only.
>
>Currently, in ASP, I refresh the frame itself, which works fine. However,
I
>now need to highlight a changed price, as it happens, using some kind of
>highlight-fade DHTML sequence..
>
>Hunting around, there seem to be two ways to do this:
>1. Use a Web service behaviour
>2. Use DotNet remoting
>
>Has anyone grappled with live data refreshes yet? So much of the
>documentation assumes there will always be some kind of user response (push
>a "refresh" button, edit a record etc)...there isn't a lot on what the
>_best_ way to do dynamically refresh a dataset is...without any interaction
>and using a timer or something....
>
>Any help appreciated
>Regards
>John Butler
>
>
>

[Jason]

This is one of the most basic and fundamental limitations of HTTP. You can't
have "events" from the server to the client. The only way to pass data is
for the client to send a request and then receive a response from the server.
This is also a fundamental limitation of Web Services, since they are built
on HTTP.

Note that this is NOT a .NET limitation - it exists for Java, Perl, C++,
and assembly language as well. Anything that uses HTTP will have the same
limitation.

The way to get around this is a bit painful. You have to write your own
messaging service. You also have to write a "rich client," something like
a .NET applet that plugs into the browser. .NET provides most of the stuff
you need to do this, but it can be complex to implement. Certainly more
complex than doing a simple web app. Microsoft has made web development
almost laughably easy with ASP.NET and Web Services, so if you can live with
a polling solution (check every 15 seconds - which severely limits scalability
of your system), then you should try that first.

"David Rothgery" <drothgery@alum.wpi.edu> wrote:
>
>"John Butler" <nospamjrbutler@btinternet.com> wrote in message
>news:3c59c28e@10.1.10.29...
>>
>> "Hari" <v_hari@indya.com> wrote in message news:3c57bbc5$1@10.1.10.29...
>> >
>> > <META HTTP-EQUIV="REFRESH" CONTENT=15> - This meta tag will send the
>> request
>> > to the server in every 15 sec. Hope this will help you!
>> >
>> > - Hari
>>
>> Thanks but I am already doing it that way...I'm looking for a better
>way....
>>
>> Obviously not many people have wrestled with displaying (constantly
>> changing) data in a browser with DotNet yet....<sigh>
>
>It's more that there really isn't a good solution to that problem.
>
>
>--
>Dave Rothgery
>david_rothgery@stratagene.com
>
>
>

[John Butler]

"Jason" <jason@creative_nospam_corp.com> wrote in message
news:3c6456b2$1@10.1.10.29...

Thanks for the reply..for those of you interested, I've actually found a
solution:

I built a webservice to retrieve the data, as per the normal documented
methods. Then I use a Microsoft Scripting behaviour to call the web method
from the client side. Works like a charm...I have a web page with live data
updating dynamically every 10 seconds, without any page refreshes. I'm now
working on pretty-ing it all up, so that changes to the table cause a
highlight-fade of the cell when they occur.

It's a solution limited to IE5+, but since it is for a corporate intranet,
that is no problem.

IT was quite painful getting around to what the solution should be, but it
is great to have found such a workable solution (for intranets)

Rgds
John Butler

[John Butler]

"Jesper Gjedde" <jg@tocsi.dk> wrote in message news:3c6250d7$1@10.1.10.29...
>
> Look into remote scripting.
> Brent Ashley have made an example of how to make a VERY lightweight Remote
> Scripting based on ASP.
> I have used it for an application, that refreshes a table every second
using
> this and DHTML.
>

Thanks for the info Jesper...I found another solution as in the post above,
but the one you mention is less browser-specific...I'll be sure to look into
it.

Rgds
John Butler

[Derek]

I'm really interested in the details of how you did it..can you please tell
me more information..


"John Butler" <nospamjrbutler@btinternet.com> wrote:
>
>"Jason" <jason@creative_nospam_corp.com> wrote in message
>news:3c6456b2$1@10.1.10.29...
>
>Thanks for the reply..for those of you interested, I've actually found a
>solution:
>
>I built a webservice to retrieve the data, as per the normal documented
>methods. Then I use a Microsoft Scripting behaviour to call the web method
>from the client side. Works like a charm...I have a web page with live data
>updating dynamically every 10 seconds, without any page refreshes. I'm now
>working on pretty-ing it all up, so that changes to the table cause a
>highlight-fade of the cell when they occur.
>
>It's a solution limited to IE5+, but since it is for a corporate intranet,
>that is no problem.
>
>IT was quite painful getting around to what the solution should be, but
it
>is great to have found such a workable solution (for intranets)
>
>Rgds
>John Butler
>
>
>