By way of introduction, I have an application utilizing three AJAX 
CascadingDropDown lists whose contents are served up by one of three 
WebMethods.  The first two of these three dropdowns are for Entity Type and 
Entity Groups.  The Entity Group gets populated based on the Entity Type 
selected from the first dropdown.  The problem is the Entity Group also needs 
to be limited by the Area ID for the area in which the user is working.  From 
all the documentation on CascadingDropDown lists I've seen, they can pass on 
only one parameter to a WebMethod.  The only solution I can think of is to 
have a separate WebMethod which would take the Area ID and store it as an 
integer property in the WebService which could then be retrieved when the 
WebMethod for populating the Entity Group dropdown requires it.  

The asmx file for the WebService is located in the same directory in which 
the aspx page requiring it is located and the code-behind for the service is 
in the App_Code directory off the application's root directory; in other 
words, it isn't exactly a standalone WebService.

My questions are as follows: 
        When the WebService is first used, does it continue to run in memory 
on the
    server after a user has finished calling the required WebMethods waiting 
on
    another request from that user?
        If several people require use of the WebService, is a separate 
WebService
    instantiated for each of the users or is there only a single instance of 
it?

If there is only a single instance of the WebService, I'll have to rethink 
using the CascadingDropDowns.  This is due to a scenario in which User A, who 
is in Area 1, is utilizing the service and then User B, who is in Area 2, 
also requires it; in this case, the Entity Group for each user would then be 
based on whoever the last person was to set the Area ID property according to 
their area.

"AlBruAn" <albruan@hotmail.com.(donotspam)> wrote in message 
news:8A05BFC7-6799-40D2-BAAB-5C3E87B0E531@microsoft.com...

> By way of introduction, I have an application utilizing three AJAX
> CascadingDropDown lists whose contents are served up by one of three
> WebMethods.  The first two of these three dropdowns are for Entity Type 
> and
> Entity Groups.  The Entity Group gets populated based on the Entity Type
> selected from the first dropdown.  The problem is the Entity Group also 
> needs
> to be limited by the Area ID for the area in which the user is working. 
> From
> all the documentation on CascadingDropDown lists I've seen, they can pass 
> on
> only one parameter to a WebMethod.  The only solution I can think of is to
> have a separate WebMethod which would take the Area ID and store it as an
> integer property in the WebService which could then be retrieved when the
> WebMethod for populating the Entity Group dropdown requires it.
>
> The asmx file for the WebService is located in the same directory in which
> the aspx page requiring it is located and the code-behind for the service 
> is
> in the App_Code directory off the application's root directory; in other
> words, it isn't exactly a standalone WebService.
>
> My questions are as follows:
>        When the WebService is first used, does it continue to run in 
> memory
> on the
>    server after a user has finished calling the required WebMethods 
> waiting
> on
>    another request from that user?


No. After each request, the instance of your [WebService] class is 
discarded.


>        If several people require use of the WebService, is a separate
> WebService
>    instantiated for each of the users or is there only a single instance 
> of
> it?


A separate instance of the [WebService] class is instantiated for each 
request. It has nothing to do with the "people", just with the requests.


> If there is only a single instance of the WebService, I'll have to rethink
> using the CascadingDropDowns.  This is due to a scenario in which User A, 
> who
> is in Area 1, is utilizing the service and then User B, who is in Area 2,
> also requires it; in this case, the Entity Group for each user would then 
> be
> based on whoever the last person was to set the Area ID property according 
> to
> their area.


You should rethink your idea of storing state in the web service, for 
several reasons. The first is that state costs scalability, so you should 
get into the habit of writing stateless services.

Also, it doesn't sound like you need to store state. If you need to pass 
area id plus the entity type, then pass them as a string, separated by comma 
or "|" or something. Let the web service split the string into its two 
pieces.
-- 
John Saunders [MVP]