Writing a service and GUI

[songstre]

I would like to write a service that handles certain tasks fro a third
party back end. There is an API for the back end that I can use to
accomplish this, but there are certain calls I have to make to the API
that put up a UI. There is no way to aviod the UI, but if write the
service will it crash when the API trys to put up a UI? I'd really like
to know this before I go ahead and put all the effort into writing the
service. Any help would be greatly appreciated. Thnx.

[Peter Bromberg [C# MVP]]

songstre,
If you set up your Service to allow interaction with the desktop, it can put
up a GUI, but this is generally inadavisable since a service starts running
before there is anyone actually logged into the machine. If it attempts to
put up its GUI and nobody has logged, on, you have big problems.

Maybe you should look into factoring out the gui portion as a separate
application or even a web application that can communicate with the service
via TCP sockets, Remoting, or even named pipes.
Peter

--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"songstre" wrote:

I would like to write a service that handles certain tasks fro a third
party back end. There is an API for the back end that I can use to
accomplish this, but there are certain calls I have to make to the API
that put up a UI. There is no way to aviod the UI, but if write the
service will it crash when the API trys to put up a UI? I'd really like
to know this before I go ahead and put all the effort into writing the
service. Any help would be greatly appreciated. Thnx.

[songstre]

<<factoring out the gui portion >>
Yes, I'd like to. But it's the dll of the API that's popping it up and
I have no control over that. But the method call that pops it up
(Search) is the only method that provides me the functionality I need.
Eventually I will write my own product for this (image storage and
retireval), but uuntil then, I needed to know if this dll showing a GUI
is going to make my service crash or not.

[John B]

songstre wrote:

<<factoring out the gui portion >>
Yes, I'd like to. But it's the dll of the API that's popping it up and
I have no control over that. But the method call that pops it up
(Search) is the only method that provides me the functionality I need.
Eventually I will write my own product for this (image storage and
retireval), but uuntil then, I needed to know if this dll showing a GUI
is going to make my service crash or not.

I dont think it would make it crash.
It would just hang(wait) until the gui disappears presuming it is single
threaded.
You might need to spawn another thread maybe, to find and kill the gui
when it appears.
Not clean or guaranteed to work :)

JB

[Willy Denoyette [MVP]]

"John B" <jb******@yahoo.com> wrote in message
news:44**********@news.iprimus.com.au...
| songstre wrote:
| > <<factoring out the gui portion >>
| > Yes, I'd like to. But it's the dll of the API that's popping it up and
| > I have no control over that. But the method call that pops it up
| > (Search) is the only method that provides me the functionality I need.
| > Eventually I will write my own product for this (image storage and
| > retireval), but uuntil then, I needed to know if this dll showing a GUI
| > is going to make my service crash or not.
| >
| I dont think it would make it crash.
| It would just hang(wait) until the gui disappears presuming it is single
| threaded.
| You might need to spawn another thread maybe, to find and kill the gui
| when it appears.
| Not clean or guaranteed to work :)
|
| JB

And how would you know it appears when there is no active desktop? Realy
this is something you should never do, the popups will or block the
application or they will simply add up dending whether they are modal or
non-modal dialogs. Each dialog will consume valuable GDI and user space (non
pooled memory), until the moment no space is left and the system halts.

Willy.

[Willy Denoyette [MVP]]

"songstre" <so******@gmail.com> wrote in message
news:11**********************@j55g2000cwa.googlegr oups.com...
| <<factoring out the gui portion >>
| Yes, I'd like to. But it's the dll of the API that's popping it up and
| I have no control over that. But the method call that pops it up
| (Search) is the only method that provides me the functionality I need.
| Eventually I will write my own product for this (image storage and
| retireval), but uuntil then, I needed to know if this dll showing a GUI
| is going to make my service crash or not.
|

No one can answer this question, the library was never meant to be used from
a service, so it's not tested in such an application. If you need to know,
you will have to test it yourself, all we can say is that it's a bad idea to
use it in production, not only because of possible UI issues, there are also
other thing's to keep in mind, a Windows service is sandboxed in a separate
security context, you can't access the interactive users profile nor it's
environment, who guarantees the library doesn't need this?

Willy.

[songstre]

All great points. Thanks everyone. I know that there is a component
that was written by a co-worker that uses the library. It is run as a
Scheduled Task rather than a service and has been working, for the most
part. Any comments on this? The GUI that pops up when the search is
executed is informational and goes away automatically.

[Brian Gideon]

I've been in this situation as well. There's not much you can do about
it. Try to get the vendor to change the library.

Brian

songstre wrote:

I would like to write a service that handles certain tasks fro a third
party back end. There is an API for the back end that I can use to
accomplish this, but there are certain calls I have to make to the API
that put up a UI. There is no way to aviod the UI, but if write the
service will it crash when the API trys to put up a UI? I'd really like
to know this before I go ahead and put all the effort into writing the
service. Any help would be greatly appreciated. Thnx.

[John B]

Willy Denoyette [MVP] wrote:

"John B" <jb******@yahoo.com> wrote in message
news:44**********@news.iprimus.com.au...
| songstre wrote:
| > <<factoring out the gui portion >>
| > Yes, I'd like to. But it's the dll of the API that's popping it up and
| > I have no control over that. But the method call that pops it up
| > (Search) is the only method that provides me the functionality I need.
| > Eventually I will write my own product for this (image storage and
| > retireval), but uuntil then, I needed to know if this dll showing a GUI
| > is going to make my service crash or not.
| >
| I dont think it would make it crash.
| It would just hang(wait) until the gui disappears presuming it is single
| threaded.
| You might need to spawn another thread maybe, to find and kill the gui
| when it appears.
| Not clean or guaranteed to work :)
|
| JB

And how would you know it appears when there is no active desktop? Realy
this is something you should never do, the popups will or block the
application or they will simply add up dending whether they are modal or
non-modal dialogs. Each dialog will consume valuable GDI and user space (non
pooled memory), until the moment no space is left and the system halts.

Willy.

You are of course correct :)
That is why I appended the | Not clean or guaranteed to work :)

line at the end.

WRT the active desktop(or lack thereof), I havent tried this but if I
was running a thread spawned from the service thread then I would
presume (maybe incorrectly) that I could get access to these popups when
they appeared.

As I said, not pretty but it would be _a solution_ to the problem if it
worked as I anticipated.

JB