I have a One way WCf Service which will just log entries in database.Normally it will run for 10 - 20 mins . Is there any way to cancel the service when any need arises ?
On button click i'l be triggering the one way WCF service . Now m planning to add cancel button which should stop currently triggered service. Could anyone help me in achieving this.
You can either make the operation IsOneWay, or implement the asynchronous pattern. To prevent threading issues, consider using the SynchronizationContext. Programming WCF Services does a great job at explaining these.
You can even consider using a BackgroundWorker.
Here is a nice Guide regarding Async and Sync calls:
http://www.codeproject.com/Articles/91528/How-to-Call-WCF-Services-Synchronously-and-Asynchr
Related
I have one scheduler which is running on Windows Service. For each new event it creates new thread. Each thread then load DLL using AddIn Framework and execute the task.
It is working fine but now but according to new requirement i want to be able to kill any event if we decide to do so or event is taking much time in execution.
Code for starting thread
ThreadStart ts = KickOffEvents;
Thread t = new Thread(ts);
So to do that i need to issue something so scheduler can understand and kill specific thread. But as that scheduler hosted on window service i am not able to do so.
Can anyone tell any work around in this???
Currently i am working on to move scheduling functionality to IIS by creating WCF service. Then i will be able to call function of wcf service which will in a way kill any event(thread).
Can anyone provide any input in whether any underlying risk in doing so???
Thanks in Advance
There is no way for the scheduler to explicitly kill the thread it has spawned. You will need to set a flag that the thread looks for and it will have to bring itself down. Anything else can result in undefined behavior
You can use a WCF service request to set this flag
I am trying to figure out the best way to approach this design... Here is some background of what I'm trying to do:
I have a simple digital I/O controller that sends data to my computer via Ethernet. I have a program that can receive this data over Ethernet. I would like a separate front end application that presents this data in a GUI. I am trying to figure out the best way to interface the program that grabs the I/O data over Ethernet, and the program that displays this as the front end. This interface should run whenever the computer boots and constantly poll the I/O in the background.
I've read about Windows Communication Foundation (WCF) and this seems like a nice way to do this. As the windows service would quietly keep polling the I/O and any clients that attach to the WCF interface can present this data in a GUI.
Am I going about this all wrong? Does this seem like a good way to do things? How will my front end clients grab the data from the WCF service?
Thank you in advance.
That's precisely the way I have done it - hosting a WCF service in a Windows service. The Windows service is the process; the WCF service is where the work is done.
In my case, my WCF-based CollectionService is on standby most of the time. I use WCF to start and stop the collector because the WCF programming model makes this easy. However, to get the data from the collector to the UI, I use a TCP socket, not WCF. I know that WCF has a streaming mode, but (1) I've never used it and (2) I believe there is some amount of overhead using WCF this way. The socket is simply a comfortable fallback for me, but I think WCF could be made to work.
If you're just starting, you can refer to these two answers for getting your Windows service up and running using C#. From there, you'll just need to create the ServiceHost and close it in the OnStart() and OnStop() callbacks of your Windows service, respectively.
Easiest language for creating a
Windows service
How to make a
.NET Windows Service start right
after the installation?
If you are new to WCF, take a look at this SO question.
Good and easy books/tutorials to learn WCF latest stuff
One more thing. In the course of your work on this, you may find that you want the WCF service to provide events to your UI when certain things occur. For example, you might provide an event that periodically notifies the UI of the number of bytes that have been received. For this, I would strongly recommend this article by Juval Lowy, one of the WCF gods.
What You Need To Know About One-Way Calls, Callbacks, And Events
His Publish-Subscribe Framework is available for free at his website, IDesign.net, along with several other working WCF examples.
Hope this helps.
I am creating an application in Silverlight using Ria Services that can take quite a bit of time once the service call is initiated. I've looked for ways to increase the WCF service timeout, but the more I think it through, this is not the right aproach.
What I would rather do is call the DomainContext and return right away, then have the client poll the server to find out when the long running query is complete.
I'm looking for a pattern or example of a good way to implement something like this. One potential issue that keeps coming to mind are that web services should not keep state between service calls, but this is exactly what I would be doing.
Any thoughts?
Thanks,
-Scott
Take a look at the WCF Duplex Service. It should solve your problem.
Can you make the service call take less time? If not, why not?
Typically when I've seen queries take this long, it either means the SQL running at the end isn't efficient enough, the SQL server has poor indexes, or the client is requesting far more data than they'll actually be able to use in a short period of time.
For example, instead of requesting 500 entities right away and showing a large list/DataGrid/whatever, why not request 10-50 at a time and have a paging UI that only requests the next batch when the user nedes it?
Take a look at signalr, it can run side by side with ria and it lets you push messages back to the client from the server.
I have to design and implement a way to deal with long running processes in a client/server application. A typical long running process would/could take 2-3 minutes. I also need to report progress to the UI in the meantime and keep the UI responsive.
Having these in my mind I though of a few solutions:
One async request to start the process which starts the server-side process and returns an assigned LRPID (Long Running Process ID) then poll periodically from the client using that LRPID. (Pro: simple to deploy, no firewall messing around Con: Unelegant, resource consuming etc.)
Use a duplex binding (such as NetTcpBinding) and initiate callbacks from the server as progress is being made (Pro: Elegant, efficient, Con: Deployment nightmare)
[Your suggestion???]
What would be your take on this?
Here is a post by Dan Wahlin about how to create a WCF Progress Indicator for a Silverlight Application. This should be of some help.
If you do not want to have to worry about the client's firewall, etc... I would probably go with your first solution and use a BackGroundWorker to make the call in order to keep from blocking the UI thread. I did this recently for an app where a request to generate a report is put on a queue and is retrieved once it is done. It seems to work well.
Another way (without having to change the WCF binding) is to use a WebBrowser control in the WPF client, and SignalR to post progress messages from the server to that control.
Note that to avoid javascript errors that happen with the WebBrowser control (because by default it seems to use Internet Explorer version 7 which doesn't seem to be compatible with jQuery.js), you will need to add keys to the registry on the client machine to change the default for the client app to use IE10 or later - see http://weblog.west-wind.com/posts/2011/May/21/Web-Browser-Control-Specifying-the-IE-Version).
This could be a deployment nuisance (because admin rights seem to be needed - eg on a 64 bit Windows 8.1 pc - to add the registry keys).
Also, it still seems necessary to call the long running WCF method in a separate thread, otherwise the WebBrowser control doesn't seem to update its display to show the SignalR messages it is receiving. (This makes sense because the UI thread would otherwise have to wait until the WCF call had finished).
But I mention it as an alternative approach using a newer tool (SignalR) :)
I have a Windows service that's running all the time, and takes some action every 15 minutes. I also have a client WinForms app that displays some information about what the service is doing. I'd like the forms application to keep itself updated with a recent status, but I'm not sure if polling every second is a good move performance-wise.
When it starts, my Windows Service opens a WCF named pipe to receive queries (from my client form)
Every second, a timer on the winform sends a query to the pipe, and then displays the results. If the pipe isn't there, the form displays that the service isn't running.
Is that the best way to do this? If my service opens the pipe when it starts, will it always stay open (until I close it or my service stops)? In addition to polling the service, maybe there's some way for the service to notify any watching applications of certain events, like starting and stopping processing? That way, I could poll less, since I'd presumably know about big events already, and would only be polling for progress.
Anything that I'm missing?
I would steer clear of polling if possible. You're much better off adopting an event-based mechanism, which reduces overhead and provides just-in-time status updates as necessary.
You're already ahead of the curve. WCF is definitely the way to go here for .NET-based applications. And since your form and service are on the same system, the named pipe binding is the one to use as well. Now all you need is to have your service publish events, including periodic status updates, that your form can listen to when it's open.
The easiest way I've found to do this is to use Juval Lowy's Publish-Subscribe Framework. The neat thing about this framework is that it decouples the publisher from the subscriber. The publisher publishes events, not caring if a subscriber is there or not. If a subscriber is present, the event is forwarded for its consumption. Based on your description, I think this would work very well for you.