We are developing a web application in ASP.Net and C#. The requirement here is to interact with a third party exe which is developed in Fortran77. This third party exe produces an output file after being provided with some inputs and shuts down.In windows desktop single user application this is easily possible by using System.Diagnostics.Process and the events provided therein. But in web there will be multi-user environment, and many calls will be made to this exe. What are the best possible ways to handle such an exe in web application?
Is it fine if we invoke exe on each user request as the exe shuts down after generating output file? Or
Is it possible to use windows service? Or
Any other approach?
Thanks in advance.
-Prasad
Typically, invoking a different process to do some job (for a request) does not scale well when your number of requests start growing. Said that, if the process invocation is not going to happen frequently then you should be OK. The number of concurrent requests and through-put etc will really depend on your server hardware and the best bet would be to load test the server. As such you should use Process class to launch the process to get the work done.
Yet another issue that is possible that your legacy executable does not support multiple instance. It's unlikely but there are quite a few desktop windows application that check for existing instance. So in such, you cannot launch process concurrently and only way would be to create a queuing logic - you can create a in-process queue (in your web application) or create a external application (such as windows service) that will do queuing.
There can be alternate approach for this solution that is useful when the time taken for process to complete is large (so that you cannot block your web requests till the job is complete) and/or you need to scale your app to support more load. Essentially idea is use producer-consumer pattern where your web server will add requests to a persisted (e.g. table in database) queue and then you have multiple machines/servers running a job/windows service that would read from this queue and run the process to generate file.
Related
I'm wondering what the preferred architecture would be for the following situation:
I'm required to have a .NET application that will perform batch upload of multiple data files concurrently to a SQL Server. This will be invoked from a WPF application which will allow the user to select the files and the destination tables, as well as reporting on the individual progress for each upload (including error messages). I have absolutely no problem writing the code for any of this. However, there is a requirement that the user is able to close the WPF application altogether and for the upload process to continue. Further, if the user restarts the WPF application from the same machine, it should be able to get a handle on the existing uploads and report on the status as if the program were never closed.
My question is what are the ways of achieving this and which would seem the most standard/suitable?
I've considered simply not actually closing the WPF application but hiding all the windows, but this seems a cheat. Would it be best to create a WCF service on the server where the upload is taking place and simply upload the file? I don't think I can do that and report progress % etc though. What about a locally-running Windows Service, can I achieve a similar effect? Should I be thinking of MemoryMappedFiles?
Appreciate all your thoughts.
Because you are talking about long-running task, I would use local Windows Service communicating with your WPF application through MSMQ. For example, each file to upload can be represented by one MSMQ message. Your WPF application will be putting messages into queue and Windows Service, periodically and without any impact if WPF is running or not, should take it from queue and process. This will provide simple and reliable channel of providing tasks (uploads).
To provide internal status of the Windows Service to its clients (your WPF application), I would host inside it a WCF endpoint with simple service that is telling, for example, about progress.
I have an ASP.NET MVC website which clients post files to as part of an order process. These files can be up to 200MB. I have a need to transfer these files to another server via FTP. I don't really want to burden IIS with this. So was thinking of writing c# app to handle the file transfer which ran every x minutes and use windows service to run it.
Would this be an ok solution or is there something that could handle this for me already?
If I wrote the application should I let windows service handle the scheduling i.e. start the app every x minutes or should I just get it start the app on say startup and let the app handle the sleep/wakeup.
I was envisaging something quite rudimentary. Using SQL to track what needs uploading and has been uploaded. Are there any other considerations particular to a window service?
The website runs on iis8 on a windows 2012 vps.
One architecture tip -- use a simple executable and a scheduled task rather than write a service. You don't need to worry about memory leakage over months then.
You could probably implement this without writing any code -- you can script ftp.exe pretty effectively. I'd just script it to push all the files, and then, presuming FTP.EXE exited with 0, to clean out the uploads folder and rinse and repeat.
Environment: C#.NET VS 2012
We need to write an order delivery process. Basically it runs through the orders tables and and creates a file every night, that contains orders that are received on that day.
Traditionally we build this using Windows Console Application and a scheduled task wakes up this console application at every night (or every 6 hrs) to deliver the files
We are planning to re-write this console application. We are leaning towards both approaches i.e.
Approach 1: the scheduled task would run to deliver the order every night
Approach 2: ASP.NET web apps, that would also deliver the orders.
I am new to WCF, not yet tried it, is this a good situation to use WCF?
If so, can someone throw me some basic points how to implement this.
FYI: I have implemented another approach for some other client, where we have a ASMX web service that does this job, and the console application just calls the web service.
One disadvantages we have with this approach is, the file creation and delivery and everything is done through IIS and we prefer not to use IIS if it needs to be called from Windows Scheduler. This is for performance reasons.
Thanks
Suresh
Keep it simple. Run a console application as a scheduled task.
An IIS app (WCF service or WebApi) would only be useful if you get job requests, i.e. acting as a server.
We have developed some long running C# console applications which will be run by Windows Scheduled tasks.
These applications might be run on many different server machines on intranet/extranet.
We cannot ensure that they run on one machine because each application might need access to some resources, which are available only on a certain machine.
Still, all these applications are using a common WCF service to access the database.
We need to ensure, that there is only instance of one of our applications running at any moment.
As the apps might be on different extranet computers, we cannot use per-machine mutexes or MSMQ.
I have thought about the following solution - WCF Mutex service with a timeout. When one app runs, it checks to see if it is already launched (maybe on another machine) and then (in a dedicated thread) periodically pings the WCF Mutex service to update the timestamp (if ping fails, the app exits immediately). If the timestamp gets expired, this means, that the application has crashed, so it can be run again.
I would like to know, if this "WCF mutex" is optimal solution for my problem. Maybe there are already some third party libraries which have implemented such functionality?
You mutex solution has a race condition.
If an app on a different server checks the timestamp in the window after the timestamp expired, but before the current service had updated the timestamp you will have two instances running.
I'd probably go the opposite route. I'd have a central monitoring service. This service would continually monitor the health of the system. If it detects a service went down, it would restart it on either that machine or a different one.
You may want to bite the bullet and go with a full Enterprise Service Bus. Check the Wikipedia article for ESBs. It lists over a dozen commercial and open source systems.
How about a file lock on a network location?
If you can create/open the file with exclusive read write then it is the only app running. If this running app then subsequently crashes, the lock is released automaticaly by the OS.
Tim
Oops, just re-read the question and saw "extranet", ignore me!
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