I've been away from web development for 6/7 years now and I'm completely lost in regards to how to do things. I'm going through some tutorials on HTML5 and whatnot, but I was hoping to get a helping hand here.
I'm trying to build a (POC) website which would have the "server" monitor it's running applications and when a certain application is running change the content of a hosted page. I don't want the model to be PageLoad->Application Check, I'd rather have something like ServerStart->ApplicationHook->Callback->Model->PageLoad->CheckModel, so a hook is put in place when the server starts and the callback of the hook updates a model which the page uses to update. Although this architecture may not be the best way, in general I'm just looking for a way to have a long running process which starts when the server starts up. Eventually I'l move this to a Windows service which calls a webservice when changes are made, but for a POC I'd rather keep away from multiple applications interacting, as the Windows Service would need to be "called" by the server too and I can't think of an easy implementation of that at the moment.
So, if you were building a page which relied on events on the server and needed to be able to interact with an application on the server separately to an individual page, but the page needs to be able to "post" information back to that application what would you do?
My explanation has been a bit all over the place, so I hope at some point my question has come across clearly! :)
Maybe there're alternatives but I think your only option for this kind of setup is a Windows service. If you need to talk to it from other components, have it use sockets or listen for HTTP requests on a known port. Doing what you described from a web application is not impossible but it'd be certainly very hard since it's the web server (app pool executable) that controls what happens in the process, not your code. In a Windows service, you're in control.
Edit: here's an article about the different options for hosting a web service - it seems to me that using a Windows service is, indeed, your best choice. You may be able to use a WCF service but you'll have to talk to a local application on the server and that part may be easier to do just using a Windows service.
Related
The current project I'm working on is a Windows Form Application, which in large part functions as a background service to make Queries to a decent number of APIs and store that information into a database. Pretty straightforward.
As I implement more data sources the issue I'm running into is that one of the places I'm pulling from wants to use webhooks to push that data to me. Again fairly straightforward, I did some tutorials on making ASP.NET Web API projects and all of that makes sense in isolation.
Now what I'm confused about is to tie it all together. From my understanding, the options I have would be to have the Form application and the Web API application run separately, which seems like more separation than I want (especially considering that the webhook is for a single item of data that already ties into what the Form application is handling). Alternatively the other option would be to get the Form application to to self host a Web service which seems like the way to go, but I'm unsure of how to approach that without starting with the Web API shell.
I tried reading up on it and this and this seem to solidify that it would definitely be possible to just host the webhook receiver/controller server inside of the form application without making a new project for it. But I'm not sure of what config, new files and settings of that kind it would take.
I would be super thankful for anyone who could offer guidance about how to go about implementing this webhook controller in a project type not designed for it by default, or if you could tell me that it's a bad idea and I should make separate projects for them.
Thank you for your help!
"Webhooks" (or HTTP callbacks, in general) require a publicly routable address. At home, your desktop computer likely sits behind a NAT and with a dynamic IP address, so it won't work unless you enable port-forwarding and find out your publicly routeable address (assuming it's possible at all and you aren't running inside a restricted company or school/university network). You'll probably want to use AWS Lambda or Azure Functions as a quick and simple way of accepting messages from the public web which your desktop program can retrieve them from later-on (using a "mailbox" paradigm). You could try making it work in real-time with a WebSocket or EventSource but I don't know if that works from AWS Lambda or Azure Functions - if it doesn't then you'll need a "real" website.
I'm currently working on an ASP.Net MVC4 application to automate a production workflow.
my client would prefer the solution to be "zero footprint", so completely running in browser.
One of the issues I can't imagine how to handle is to get data from a weighing scale connected to the client's serial/parallel port from within the page.
(Obviously this can't be done from the web backend ... )
I've been digging around, assuming this could be possible through javascript/jquery, but since this is running sandboxed within the browser, I'm assuming to get stuck that way ...
One of the approaches I considered was writing a self-hosted WCF webservice to run on the client that has the scale attached (hosted by a windows service or console app or so) that exposes the scale readout. Theoretically, that would allow me to consume the webservice in the IIS backend in my MVC C# code and serve it back to the client.
The only issue with this approach is that this would require the application to be hosted locally, where we'd prefer to have it hosted by an external provider.
Is there no way to handle this on the client side exclusively?
I can't imagine I'm the first person running into this, but I can't seem to find what I'm looking for by digging around on the web ...
Any thoughts ?
Thanks in advance! Stijn, Belgium
You absolutely must have a process running on the system that has access to hardware to support reading from any hardware interface. You have a lot of options there- it could be a local service running that can read the serial port and expose a simple HTTP endpoint to the browser. You can also do ActiveX-style controls for IE or browser extensions for Chrome:
http://developer.chrome.com/apps/app_usb.html
Just as a follow-up:
I ended up creating a user-control that reads out the COM-port through PInvoke of CreateFile to open the COM-port ...
Works great, no hassle with an external process running on the client etc ...
Does require full trust in the browser, but that's acceptable, since it'll run on clients under our control ...
grtz,
Stijn
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 am making a medium sized standard LOB application. Currently its a web application but I am formulating a proposal to revamp it into a Desktop remote application. By this I mean that the database and the application server will be hosted in a remote location. The client application will communicate with the server via the internet through (either WCF / Webservices / Remoting).
My question is this: The only reason I am shifting this from a web platform is due to the constraints of the web (I dont want to do AJAX or Java scripting to minimize those constraints, so please no JS/AJAX recommendations). I have made traditional desktop applications and they are considerably fast but i have never made a remote or a distributed application. I am not sure weather the speed of the application will be faster then the web or not.
As I understand it, the remote desktop application would be much faster. For one, there wont be any post backs involved, (I hate them so much). The data will obviously come via internet, so in that respect, is it better to shift to the remote desktop just for sheer speed and power?
Any help in the right direction would be greatfull. Many thanks.
Zeeshan
I think biggest advantage of desktop clients over web applications is freedom in UI design, and you don't have to worry about any inconsistencies in the client environment, although those are not an issue if you are using a client that runs on silverlight.
Personally I don't like web applications that requires a lot of user interaction, there are some of them that is a pleasure to use but I think it is very easy to do it the wrong way and end up having a buggy or not so responsive application (probably because of the incompatibilities in browsers, I have IE, Firefox and Chrome installed on my computer and I use one for some websites because they run faster on it, and others for other sites because web pages show up correctly only on them). Though this might not be an issue for a silverlight client.
In case of network speed, depending on the things that goes on the wire even with binary serialization remoting might have quite a bit of overhead. For example along with the data it writes full class names, library names and their versions so it can get pretty big and slow even for small amounts of data (although it should still be smaller then HTTP). It also has the same problems that HTTP has over unreliable connections because it uses a similar protocol. For one project we had to write a custom serializer for some objects because binary serialization alone was generating 200K, but our custom serializer for those objects were generating 50K. Then we ended up writing our own network protocol because the one that comes with the runtime was frequently stalling over unreliable wireless networks, and remoting doesn't give any control on the socket created by it (which makes sense in terms of encapsulation but you can't close it and force it to open a new one).
(I am assuming that you are asking about remoting vs web app. not remote desktop vs. web apps, because of your note about post back, you can't avoid it with a remote desktop session)
Rewriting an application just for sheer speed? No, because probably user won't see much difference in response time.
You are somewhat ambiguous with your terminology - do you want a client app that runs on the user's machine, or do you want an app that runs on the server and the user connects via remote desktop (RDP)?
If you are talking about a client app that communicates to the server via WCF etc., then yes it will be faster than a standard web app, although it will still be slower than a native desktop app. It will be faster than the web app not just because of the lack of postbacks, but also because you will be sending pure data through the wire, not a massive amount of HTML/Javascript combined with your data. With a client app, you have several options so consider them carefully - do you want Silverlight, WPF, or a native WinForms app? Each have their positives and negatives.
If you were talking about having a client app running on the server which the user then access via RDP, then you have other considerations to think of. For any more than two concurrent users you will need to consider buying CALs so the users can connect to the server. At this point you should also be considering whether you should be running a terminal server or Citrix type setup instead of using remote desktop.
Edit
When using WCF over a WAN (internet) you will certainly have to consider how you will secure it. WCF makes it trivial to secure the channel, but you need to consider how you will do authentication - there are a couple of different ways, but you can easily google that stuff yourself. The method you choose will be important due to the limited resources or skill-sets of the users.
As for what you write it in, you can't argue with Winforms if that is where your experience is. Personally, i would never again use ASP.NET/Ajax/etc for a web type application, it would be WPF or Silverlight all the way (i would only use ASP.NET for simple web sites). You can use the express (free) versions of Visual Studio to write it in, you don't need Expression (it's just a nice to have, and is more aimed at the design side than the actual coding side). Deploying the app need not be difficult - Silverlight or WPF xbap are delivered via the web, the user has to do nothing (except for the simple install of the Silverlight plugin or installing the right .Net framework for WPF - check this link). Winforms or stand-alone WPF require slightly more work, but you can avoid most issues by writing a good installer.
Whichever you choose, make sure you don't under estimate the time for development (because you will have a bit of a learning curve), and also make sure you budget enough time for testing it - especially the security side of it :)
I have been in a similar situation, although started with a Winforms LOB application.
Heres what we found with WinForms...
It's going to be harder to deploy in your release cycle, to all client machines.
WinForms can't be run on other operating systems easily. (with the exception on mono)
WCF endpoints can get complicated, and you need to manage an endpoint for release/version of your application.
Authentication, Authorization and Security can be tricky to get right!
Heres why you should stick to a html web application.
it's going to be easier to deploy, as you just need to copy one set of DLL's into the bin folder. Can be scripted from a continuous integration or staging server.
Security is going to be easy, by using a SSL certificate.
Silverlight/Flash should fill in the gaps that HTML leaves out.
Microsoft has also combined the connected systems in .net 3.5, they now call it WCF (ASMX/Remoting/etc...). It's got quite a learning curve 4-5 weeks.