can a Web Service retrieve data in background?

[Asus]

Hello,

I'm new to Web Services.
I'm trying to develop a Web Service that retrieves some data out of a
database and sends them to the client as a DataSet when a method is invoked.
My question is: Is it possible to run another method on the Web Service
automatically to refresh the data? That means the Web Service should interact
as a Windows Service after a certain amount of time it should retrieve the
data and stores them locally, and when a Client is connection it always gets
the data from the local source (i.e. XML file), not from the database, so the
Client doesn't have to wait until the data is available. Only the Web Service
refreshes the data in the background (without any Client invokement).

I don't know if this would be possible but I think it isn't. My guess is
that I would write a Windows Service which queries the Web Service to refresh
the data.
But how can I solve this?
I would prefer that the Windows Service gets a dynamic list of Web Services
it should refresh. So I will have to set dynamic references to these Web
Services (not in the IDE "Add Web Reference") but the invoked method could
probably always be the same (i.e. "refreshData").

Does anybody know how I can solve this?
Can I simply add a timer to the Web Service? I don't think it will work.

Thank You in advance

Best regards
Sven

[Bala]

Hi,

You haven't mentioned anything about the clients of your webservice. And,
also, what makes to think that response from DB server will be slow?

If all your clients on same domain / lan, as your webservice, getting the
response direct from your DB server shouldn't make much time at all.

if you still want to keep a local copy (a xml file) for the web service to
use, then create a scheduled job on the DB server to update this xml file. do
not disturb the web service will any service or timer.

--
The Clipper
"Asus" wrote:

Hello,

I'm new to Web Services.
I'm trying to develop a Web Service that retrieves some data out of a
database and sends them to the client as a DataSet when a method is invoked.
My question is: Is it possible to run another method on the Web Service
automatically to refresh the data? That means the Web Service should interact
as a Windows Service after a certain amount of time it should retrieve the
data and stores them locally, and when a Client is connection it always gets
the data from the local source (i.e. XML file), not from the database, so the
Client doesn't have to wait until the data is available. Only the Web Service
refreshes the data in the background (without any Client invokement).

I don't know if this would be possible but I think it isn't. My guess is
that I would write a Windows Service which queries the Web Service to refresh
the data.
But how can I solve this?
I would prefer that the Windows Service gets a dynamic list of Web Services
it should refresh. So I will have to set dynamic references to these Web
Services (not in the IDE "Add Web Reference") but the invoked method could
probably always be the same (i.e. "refreshData").

Does anybody know how I can solve this?
Can I simply add a timer to the Web Service? I don't think it will work.

Thank You in advance

Best regards
Sven

[Asus]

Hello Bala,

Thank you for your answer. The clients of my WebService will be ASP.NET
WebSites and Smart Clients or .Net Applications. Now we have a set of VB6
programs, sometimes they always do the same calculations or retrieve the same
data out of the DB. So it would be better to use a WebService instead, the
data will be retrieved only once and all Client Apps can use this data.

The response from DB Server sometimes is slow, for instance calling very
huge SELECTs or Procedures (we already have), so it would be *very* bad if
the Client has to wait until the SELECT finishes (then there is no need for a
WebService in my opinion, even if it's called asynchronously I will have to
wait until the data is available).

Yes, the client Apps will mostly work within the same LAN / domain as the DB
Server and WebServer.

But I would like to use the advantages of WebServices in my client Apps,
i.e. there is no need to connect to the DB for my client App, because the
Service already has retrieved the data.

I think about a possibility to schedule a WebService to run at a particular
time and retrieve some data from a Stored Procedure, saves them and sends
them to the client when the client needs it.

Thank You.

Sven

[Asus]

Hi,

I've found out the solution.
I simply added a Timer to my WebService and invoked
a method that starts the Timer.

So, my WebService retrieves Data every n Seconds and
stores it in the local File System as a GZipped File.

I did not think that it could be that easy.
:)

Best regards
Sven