I realise this question has been asked in different variations but with newer features to .net (e.g. async await) I wonder what solution is the best.
I have a C# .Net Web Forms app that has a long running task: The task handles a user request where they upload a csv data file, serialises into object, and imports to a database. The task can take a few minutes and the browser regularly times out - this causes usability issues.
I have seen many solutions whereas the user will upload the data and then the task is carried out in the background. The page will then call the server intermittently to request the status of the task, thus keeping the user informed of the progress.
I would like to know how this is achieved? The options I see on the table:
Windows Service
Web Service - how is this hosted: IIS or a windows service?
Async, Await - is this a possibility?
I think you could take two different approaches.
The first would be a pull approach, you would be keeping the state of the process per user in the server, perhaps in session, and having the process update that state, then the client can pull the actual state via ajax regularly. The ajax call is made from the client's browser, and the function can be put in the same web page that the client is viewing, there's no need to separate it if it's going to be used only from there.
The second could be a push approach, which is a bit more complex but gives you other possibilities. You would need to use a library like signalr https://www.asp.net/signalr, that allows you to communicate from the server to the client's browser, call JS functions, and push the updated state to the client's form. That could create a more functional two-way communication and a better user experience in exchange of a bit more complexity.
Related
Once a day, I want my ASP.NET MVC4 website, which may be running on multiple servers, to email a report to me. This seems like a pretty common thing to want to do, but I'm having a tough time coming up with a good way to do it.
Trying to run a timer on a server to do this work is problematic for a couple of reasons. If I have multiple servers then I'd have the timer running on all of them (in case a server goes down); I'd need to coordinate between them, which gets complicated. Also, trying to access the database via Entity Framework from a background thread adds the complication that I must employ a locking strategy to serialize construction/disposal of the DbContext object between the periodic background thread and the "foreground" Controller thread.
Another option would be to run a timer on the servers, but to have the timer thread perform a GET to a magic page that generates and emails the report. This solves the DbContext problem because the database accesses happen in a normal Controller action, serialized with all of the other Controller accesses to the database. But I'm still stuck with the problem of having potentially more than one timer running, so I'd need some smarts in the Controller action to ignore redundant report requests.
Any suggestions? How is this sort of thing normally done?
You should not be doing this task from your web application as Phil Haack nicely explains it in his blog post.
How is this sort of thing normally done?
You could perform this task from a Windows Service or even a console application that is scheduled to run at regular intervals using the Windows Scheduler.
The proper solution is to create a background service that runs independently of your website. However, if that is not an option there is a hack where you can use the cache as explained in Easy Background Tasks in ASP.NET by Jeff Atwood.
A few options:
If you are hosting on Azure as a Website, check out WebJobs which was released recently in preview (http://azure.microsoft.com/en-us/documentation/articles/web-sites-create-web-jobs/)
If you don't want the pain of extracting out your email logic outside of the website, expose that functionality at a url (with a handler, mvc action, etc.) and then run a Windows Scheduled task that hits that url on a schedule.
Write a simple console app that is executed similarly via a Windows Scheduled task.
Or write a simple Windows Service that internally is looping and checking the time and when reached, hits that url, runs that exe, or has it's own code to send you the email.
I would recommend running Quartz.NET as a Windows Service:
Quartz.NET - Enterprise Job Scheduler for .NET Platform
There's boilerplate code for a Windows Service in the download.
I need to tell the Database Handler that it should run a script which generates 300-500MB of data, then notify my C# application that the script has completed.
After that I need to get the newly created data to my C# application, manipulate it then send it to an FTP-server.
One way to do this would be to call the SQL-server via a web service, let the Database Handler run the script, then return the data. The C# application would then manipulate the data and finally send it by FTP. However because of the size of the data and the run-time of the script being around 1 hour this method is far from optimal.
Any suggestions on a better solution?
EDIT: I forgot to mention some important parts. SSIS was something I thought of as well. The problem is that the database is on a different server which doesn't have ports open for sending via FTP.
I would implement this as a service. Use the web service to allow users to request execution of the script (queue a request), but actually execute the script from the service (read the queue and perform the action). You have far greater control of the entire data gathering and delivery process from within the service.
My own strategy would be to develop a standalone application (installed on the server) to perform the data retrieval, manipulation and FTP transfer. This application could be executed by code in your ASP.NET application as a result of some user interaction perhaps, and could update the database as to its progress so that your user could have some feedback via the ASP.NET web interface (ajax polling or loading a status page).
Have you considered using SSIS? One of the things it is really useful for is controlling data-centric multi-step workflows.
I was not quite sure how to phrase this question.
What I want to do is create a simple server type application in C# which simply listens for incoming socket connections and handles them the way I specify. It could be a chat application or something like that, very simple.
I looked at the example: http://msdn.microsoft.com/en-us/library/fx6588te.aspx about asynchronous sockets.
I understand the code in the example except I'm uncertain about how the code would execute. Specifically, what would be the entry point of the application in the example? How would the server know to start it?
My only experience with IIS is in web forms with C# codebehind. I understand that the code for web forms is executed when the url points to the location and then again on postbacks etc.
Where it gets foggy for me is when I don't want to use a web form but simply a collection of C# class files with a single entry point (similar to a java application).
Edit for clarity:
The goal of what I want to do is to create an application which I can put on my web host which will continuously accept requests from client applications and handle them the way I will specify and then return information to the clients. I'm just not sure how to tell the server to start the application since I only know about web forms.
Also, it would be fine if I needed to initially direct my browser to a web form and, say, press a button to start the application. In fact, it would be ideal if I could start and stop the application at will.
Also, I may have used incorrect terminology. I thought IIS servers were what you called a server which can run asp.net applications. I could be very wrong about this.
Thanks.
you cannot use IIS to start windows applications, you need a windows service application that constantly listens to the port specified, and that windows service application needs to be scheduled to start either at system start up or at any event of your choice. and that windows service applications needs to stay in memory as long as you want your app to function.
PS: your question seriously needs some editing, but I am also new to SO, so I will let respectable senior users to do what they are best at.
EDIT: If you want to simulate windows service using IIS than here are your closest bets, please follow the links to know what you need to know.
Simulate Windows Service Using ASP.NET App
Forcing your Application to Stay alive
These two links will help you keep alive your application and bamm, you can create any number of classes (Java style as you quoted) to perform whatever tasks you want it to perform
It sounds to me like you don't want to use IIS at all. IIS handles the listening for you and is the "service" to manage requests. If you are lookng to manually listen for incoming connections, then you will need the following components:
A windows service running that has..
A http listener built into it.
Take a look at the C# HttpListener class and look at the process for building a window service that can run in the background of your server.
This isn't all that difficult, but I'm not so sure it's what you need. If you don't want to use webforms, you can have a web application that resolves requests straight to custom handlers which i THINK is what you're actually looking for and makes having your own listener overkill.
EDIT: Additional info on custom handlers
Here is a start on what a custom handler is and how to use it:
http://support.microsoft.com/kb/308001
I would also look at some beginner articles on MVC3 from .net. MVC is a framework that doesn't have any of the fluff (such as viewstate) that webforms has and allows you to route a URL (request) to a Controller (class) and return pretty much anything you want. There are a lot of advantages to using MVC and if you are coming from a java/pure http background it will make much more sense than webforms.
You can get started with that one by searching around for "getting started with .net MVC3" or even start with www.asp.net for beginner resources.
Unless your goal is to learn low level TCP communication, writing and configuring services, dealing with code changes, writing own serialization/request parsing than sticking with IIS and HTTP maybe easier approach.
There is no need to use WebForms - WebService (ASP.Net or even WCF) or MVC Web API will give you ability to implement methods you want without need to write your own custom serialization and request parsing infrastructure. You can even do long poll if/when needed (i.e. SignalR).
I'd start with basic MVC application reporting JSON results as server side as it will still show all issues involved with writing chat client (persistence, discovery of other clients, quick status updates) while allowing you to focus on communication itself (including easily see all traffic if need).
I have a question that is perhaps slightly towards architecture and design rather than syntax problem....
I have a c# winforms app on my desktop which I have built which is similar to a CRM. I make updates to customers records as they submit orders/invoices etc and what I would like to do is to build (or buy) a module that will update a remote database that sits behind a website onto hich registered clients log in. I want the clients to be able to see the status of their invoice/purchase etc as I have updated it on the winforms app.
I can think of a couple of options of the top of my head but would like to know more if you have done something similar
Things I am considering are;
>Replication - I think this is overkill as the updates are not
huge, are one way only, and not
critical they are in real time, and
also I am running SQL express on the
winforms app. This can be changed
but rather not
>create a text/xml file that gets created and uploaded to the web
server to a location that is
monitored every 5 minutes and then
updates the web database. - I am not
hosting the website myself so I do
not have complete control over what
I can install but I suspect I can
install a .NET 'filewatcher'
Anyway, I would appreciate your thought on my 'problem'
thanks
I think your best bet is to create a web service of some kind (I like using ServiceStack.net to create simple REST ones, much cleaner imo than WCF). This will sit on the server and be responsible for the server-side sync piece.
On the client, you could either have the winforms app fire off the call to the web service based on some threshold of activity, or you could have a windows service that you install with the winforms app which does it in a scheduled job or on a timer.
You'll want to be sure that you're doing all your calls over SSL of course, and make sure you're authenticating the clients, but that's the basic architectural approach I'd take.
I have a data loading application that has to be executed multiple times per day at irregular intervals. I am planning to write a service to kick off the downloads and import the data to a database server. Are there advantages to using a standard service over a webservice or vice versa?
I think you're missing the point here.
Web Services typically are used for a form of communication or remote execution. You call a remote function on a web-service to either adjust the behavior of the machine it's running on or to retrieve data from it.
Windows Services are background processes that run on a machine without any "logged on user" being required. They can perform tasks and do things while the user is at the login screen, or do elevated operations. You can talk to services to adjust their behavior or retrieve information, but it's general purpose is different than a webservice.
The biggest notable difference here is that web-services must be called, they don't run on their own.
For your application I would suggest using a Windows (Standard) Service, as you can have it execute code once per day. I would only use a web-service if you've got something else to automate the calls to the web-service and you require a response from the server detailing it's execution result (success/fail/warning/etc...)
You could also consider writing a normal (windows or console) application that is triggered by a Windows Scheduled Task. What you've described doesn't necessarily sound like something that would require a service.
Sounds like a good use of a windows service to me. Off the top of my head, I'd use a windows service if:
1. Work is performed on a scheduled basis (regular or irregular intervals) in the background;
2. No interaction is needed - work is just done in the background and kicks off based on polling or some other type of trigger (message dropped in queue, database value trigger, scheduled timespan, etc.);
3. Needs to be monitored (either starts/stops along with logging) and you can take advantage of WMI, perfmon and event log with little effort.
A web service is better for tasks that are interactive (like if you wanted to initiate the download based upon a request received).
Sounds like a windows service is the approach you should take.
Hope this helps. Good luck!
If "irregular interval" does mean, the application is invoked by another application, I would use a web service.
If the action is scheduled, I would use a windows service.
If you are working with SQL Server (scheduled or not), I would also consider SQL Server Integration Services.