I'm trying to get started with an application that definitely requires some GUI for configuration management and the application has to poll a web service about every hour (to check for updates/messages) or so. Also, the application is expected to run constantly in the background/system tray.
I'm looking for some guidance on the overall architecture for this application design. Can this be a straight up WPF app or would it be better it is a windows service because of the polling and because it is expected for the application to be running all the time? Do you guys have any suggestions?
Firstly, services tend not to have a GUI. They can, but it's not advised.
What I would do, is have two applications. The service itself which performs the monitoring in question, and a user-interface application (that runs on startup), and provides an interface to the service. Communication between the two can be handled in a variety of ways.
The advantage to this is, your service will run even if there isn't a user logged on, and the UI part is present only when a user is on.
To allow for your GUI to communicate with the Windows Service you can expose WCF services on the Windows Service to provide the operations you need (e.g. Start, Stop, GetStatus, etc.).
See this article on MSDN for a starting point: http://msdn.microsoft.com/en-us/library/ms733069.aspx
Related
I have a WCF service hosted in a Windows service.
This service the WCF have one metohd and in this method I have one important line :
Process Browser = Process.Start("iexplore.exe", hostUrl);
I install Windows service as local system, but when I'm trying to invoke that method, everything seems to execute, except that one important line... and IE didn't open.
I would like to add that the method itself is not in the service itself but in one of the service dll reference
Any idea why?
http://social.msdn.microsoft.com/forums/en-US/netfxbcl/thread/63a7d1ec-7077-489a-a250-f7422f04317b
" in order to get the service to actually show the UI, you'd have to set the service in Computer Management to allow it to interact with the desktop. In the services window in computer management, go to the properties of your service, and on the Log On tab, check "Allow service to interact with desktop" "
Since Windows Vista MS has been adding lots of security-related changed esp. in the area what Windows Services can/can't do. Anything "desktop-like" (printing, accessing network shares, using Office Interop etc.) is harder and harder to get working.
You should rethink your design since IMHO any "server-like process" (for example a WCF service) can be accessed in parallel by multiple requests and thus should NOT use processes which are NOT designed for this type of interaction... what happens if your webservice starts multiple IE instances that way ? Will IE behave as you need/expect it ?
IF you really really MUST do it this way you should have
a normal desktop process hosting the WCF service
OR
two processes, one your Windows Service and one running as a normal desktop process dealing with IE... these two process communicate via IPC
Under what user is the service running? Try running it under the currently logged in user, with privileges to interact with the desktop and see if that helps.
In general, its not a great idea to have services launching GUI processes. For example, what if no one is logged on. What if many people are logged on? Should it open in all sessions... etc. Have you considered exposing a simple (e.g. Net.NamedPipes) endpoint on your service, and writing a small client UI to interact with it?
I have a C# application that needs to always be running. I originally planned on making this a windows service but I now have a requirement to make the application host a web admin console.
I haven't played with IIS in quite a few years so my question is this:
What would you recommend I use?
I've thought about making a windows service and embedding a web server such as Cassini but so far I'm not very happy with the open source web servers I've looked at.
Can IIS handle this? Do people use it for this type of scenario, and if so how?
This sounds like a job for two separate projects.
One is the original Windows Service. Windows Services are well suited for what you're doing.
The second is the Web Project that will be used to administer the Windows Service. This is the part that runs in IIS.
It depends on what you mean by always running. An ASP.NET web application deployed in IIS could very well be unloaded by the web server if there aren't any requests for certain amount of time killing all background threads. So if you want an ever running background thread it would be better suited to use a Windows Service. As far as the web admin is concerned, well, here you don't have much choice: ASP.NET in IIS. In order to do something useful those two applications should be able to find a common language to talk. So you could use a database to store the results into which could be used by both applications.
IIS will run your app on first request, not on server boot. So you will still need to run a service to ensure your app is always running.
You can use IIS as a webserver for your web admin part, and link your ASP.net app with your service by means of a configuration database (easy) or webservices (a little more tricky).
Windows and Web services are two very different creatures. A web service will expose external methods that you can implement against an application, while a windows service is an entity within itself. If you're planning on using this service on a timed interval to perform an operation, a Windows service would be the right way to go. If you use a web service, you will need to invoke the method you wish to run from a secondary application.
If you need to queue commands against your windows service, you could always create a database that was accessible by both your website and your windows service. This way you could send commands and query data between the two. Placing a web service in to serve as an intermidary between the two may be overkill.
I now have a scenario where I have 6 console apps on my server which each host a WCF service.
It's getting messy and I am now thinking about having a windows app (probably WPF) which hosts each service in a separate thread. This would mean there's a central place to manage the services as well.
I'm just wondering if anyone has implemented such an app or any advice before going forward?
I work on a system that has ~8 windows services, all hosting 1 WCF service each. To easily coordinate the execution of the services, we created a service coordinator application that when started, will start the other 8 services. This makes starting, stopping, and restarting the services really easily... and because they're windows services and not console applications, there's no desktop space lost.
The projects themselves are actually compiled as console applications, so that we can work on them easily during development (and also run them with a /debug argument to test them after they've been deployed). Maybe something like that will work for you.
...which hosts each service in a separate thread...
why? By default the WCF runtime is doing the threading for you. MSDN has a god starting point on this or have a look at Programming WCF Services by Juval.
To host multiple services in one thread you could check out this multi-service-host (using AppDomains for separation). I've done a very similar host before reading this and it is now hosting >100 services (started with 30 something) for thousands of users in a single operating system service.
When should I go for a Windows Service and when should I go for a "Background Application" that runs in the notification area?
If I'm not wrong, my design decision would be, any app that needs to be running before the user logins to the computer should be a service. For everything else use a background app. Is my decision right?
Moreover, if I need "admin privileges" for my background app, I would escalate using a manifest. Are there any other specific advantage of running as a service?
My general rules of thumb are as follows
If it needs to always run, it's a service.
If it needs to be run under a particular user account, Network Service, Local System, generally it's a service (or a COM+ application)
If the user needs some control over it, it's generally a notification area application.
If it needs to notify the user of something, it's a notification area application
The fun comes when you have the need to run something as a system account, but also interact with it. IIS is a good example of this, it's a service, but the administration is an application - it needs to be running at the startup, it needs access to particular things a user can't normal access (c:\inetpub), but the user needs to be able to start, stop and configure it.
I would design an application as a service if the applcation has a critical purpose and should never (or rarely) be closed. Windows services provide good crash-recovery options, good notifications (see the recovery tab in service property).
Also a good reason to use services is because they can run under any user ( so if you
deploy them on a server that you remote to, you can safely log out after starting the service without worring that the application will close too).
I also design services in combination with a desktop application that can interact with the service and can be used to monitor or reconfigure the service while running. This way you can have all the benefits of a tray application, in your service.
However, you should not abuse using services and only use them, as I said, for cirtical applications.
I believe your decision is almost right, however, I would add one more condition. Take for example the mysqld service (you have a choice in this case, but most people run it as a service). It's ran as a service because you want to access the service anytime through potentially multiple applications. It's important that it is responsive to all applications calling upon it, and itself, is not much of anything, other than waiting to serve other applications.
Just something I would consider as well when making my decision.
I am building an app that allows users to execute some commands on a computer by sending them through email. The server will monitor (pull) one or more email accounts and start a communication session. Some authentication is also involved. I am using the latest and greatest .net technologies.
I am thinking to expose the server as a service but then I cannot have a GUI to allow the user to configure things like passwords and email accounts. How can I separate these?
And second, the commands will be pluginable and should provide their own GUI. How can I incorporate this? The server process should be able to use the command functionality and the GUI process should allow for customization.
I have used WCF, which is Microsoft's current technology for implementing web services and/or SOA. You would create a desktop client or webpage that makes calls to the WCF service. The WCF service(s) would be your server component, and the desktop client or webpage would be your user frontend.
It's mainly not a question of how to make service itself. And communication protocol is not the main issue -- with WCF you can expose your application methods via spectre of protocols. It's merely a question of application configuration.
Main question here is how do you like to implement GUI. If your application is normal windows service, then it can't have built-in GUI. Just because service should not have it. So you'll need separate GUI application. Options:
GUI is standalone .NET application that somehow communicates with your service. Let's say via WCF. In this case plugins should also be implemented in two parts: plugin for service and plugin for GUI. I think, it would be too complex to support.
Modification of 1st variant. Both service and GUI are packed in one executable. It looks in what mode it's started (service or standalone) and either monitors mail or shows GUI. Since this is one application, the configuration is also the same. So you will have single registry for plugins. I assume, that in GUI mode application will search for started service and configure it. Drawback - GUI could be run only locally.
You make a sort of "transferrable" GUI - service sends GUI to simple client, which shows it. In this case you have one place for all app code (service and GUI), but it's executed in part in service, in part in client software. But you also need such universal client software.
Thinking a little more about variant 3 we see that solution already exists - it is web technologies. It would be simplest to implement your service as part a web site. And GUI would be another part. If you are unfamiliar with HTML and Javascript you can implement GUI using Silverlight.
In fact, you can host ASP.NET right in your service. Here is the good explanation. But I afraid it adds unnecessary complexity