I have a .NET console application that I want to start on the server of an ASP.NET MVC application. It produces output continuously for a certain time and I want to intercept this output and show it to the client in his browser window.
From another console application, I can do it like this:
public static void Main(string[] args)
{
Process process = new Process();
process.StartInfo.FileName = "RandomOutputCreator.exe";
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.OutputDataReceived += (sender, e) =>
{
Console.WriteLine(e.Data);
};
process.Start();
process.BeginOutputReadLine();
Console.ReadKey();
}
The problem is that in the MVC application, I can't push the data I read to the client, but rather rely on requests to the controller to get my data.
Something like WebSockets could maybe help me here, but I'm new to this kind of thing and wonder if there might be a "built-in" way to accomplish this.
Then there's the Web API thing. Could this be of use perhaps, since it seems to go well with MVC?
(Since I do not know what a fitting technology might be, please excuse the lack of tags and feel free to fill some in that you think fit).
This topic typically reminds me of a tutorial I followed in order to allow real-time communication from my browser to an ASP.NET application.
In summary : What you're looking for are indeed WebSocket, and there is no standard built-in functions to handle that. But, in order to help you doing some stuff, you still have the library signalR!
Here's the link to the referenced tutorial : http://www.asp.net/signalr/overview/getting-started/real-time-web-applications-with-signalr
You can try "print" console output in a separate frame (see iframe HTML tag).
You should set one of your actions as a source (URL) of the frame. You'll need to configure the IIS to run this action without execution time limit.
Next, your action should run an external program, intercept its output, and write it to HTTP output (see ContentResult).
I have a small project that does exactly that: https://github.com/vtortola/WebSocketListener/wiki/WebSocketListener-Terminal-Server
Give it a look, it may give you some ideas.
Related
We are using MediatR to implement a "Pipeline" for our dotnet core WebAPI backend, trying to follow the CQRS principle.
I can't decide if I should try to implement a IPipelineBehavior chain, or if it is better to construct a new Request and call MediatR.Send from within my Handler method (for the request).
The scenario is essentially this:
User requests an action to be executed, i.e. Delete something
We have to check if that something is being used by someone else
We have to mark that something as deleted in the database
We have to actually delete the files from the file system.
Option 1 is what we have now: A DeleteRequest which is handled by one class, wherein the Handler checks if it is being used, marks it as deleted, and then sends a new TaskStartRequest with the parameters to Delete.
Option 2 is what I'm considering: A DeleteRequest which implements the marker interfaces IRequireCheck, IStartTask, with a pipeline which runs:
IPipelineBehavior<IRequireCheck> first to check if the something is being used,
IPipelineBehavior<DeleteRequest> to mark the something as deleted in database and
IPipelineBehavior<IStartTask> to start the Task.
I haven't fully figured out what Option 2 would look like, but this is the general idea.
I guess I'm mainly wondering if it is code smell to call MediatR.Send(TRequest2) within a Handler for a TRequest1.
If those are the options you're set on going with - I say Option 2. Sending requests from inside existing Mediatr handlers can be seen as a code smell. You're hiding side effects and breaking the Single Responsibility Principle. You're also coupling your requests together and you should try to avoid situations where you can't send one type of request before another.
However, I think there might be an alternative. If a delete request can't happen without the validation and marking beforehand you may be able to leverage a preprocessor (example here) for your TaskStartRequest. That way you can have a single request that does everything you need. This even mirrors your pipeline example by simply leveraging the existing Mediatr patterns.
Is there any need to break the tasks into multiple Handlers? Maybe I am missing the point in mediatr. Wouldn't this suffice?
public async Task<Result<IFailure,ISuccess>> Handle(DeleteRequest request)
{
var thing = await this.repo.GetById(request.Id);
if (thing.IsBeignUsed())
{
return Failure.BeignUsed();
}
var deleted = await this.repo.Delete(request.Id);
return deleted ? new Success(request.Id) : Failure.DbError();
}
I have a dotnet core application.
My Startup.cs registers types/implementations in Autofac.
One of my registrations needs previous access to a service.
var containerBuilder = new ContainerBuilder();
containerBuilder.RegisterSettingsReaders(); // this makes available a ISettingsReader<string> that I can use to read my appsettings.json
containerBuilder.RegisterMyInfrastructureService(options =>
{
options.Username = "foo" //this should come from appsettings
});
containerBuilder.Populate(services);
var applicationContainer = containerBuilder.Build();
The dilemma is, by the time I have to .RegisterMyInfrastructureService I need to have available the ISettingsReader<string> that was registered just before (Autofac container hasn't been built yet).
I was reading about registering with callback to execute something after the autofac container has been built. So I could do something like this:
builder.RegisterBuildCallback(c =>
{
var stringReader = c.Resolve<ISettingsReader<string>>();
var usernameValue = stringReader.GetValue("Username");
//now I have my username "foo", but I want to continue registering things! Like the following:
containerBuilder.RegisterMyInfrastructureService(options =>
{
options.Username = usernameValue
});
//now what? again build?
});
but the problem is that after I want to use the service not to do something like starting a service or similar but to continue registering things that required the settings I am now able to provide.
Can I simply call again builder.Build() at the end of my callback so that the container is simply rebuilt without any issue? This seems a bit strange because the builder was already built (that's why the callback was executed).
What's the best way to deal with this dilemma with autofac?
UPDATE 1: I read that things like builder.Update() are now obsolete because containers should be immutable. Which confirms my suspicion that building a container, adding more registrations and building again is not a good practice.
In other words, I can understand that using a register build callback should not be used to register additional things. But then, the question remain: how to deal with these issues?
This discussion issue explains a lot including ways to work around having to update the container. I'll summarize here, but there is a lot of information in that issue that doesn't make sense to try and replicate all over.
Be familiar with all the ways you can register components and pass parameters. Don't forget about things like resolved parameters, modules that can dynamically put parameters in place, and so on.
Lambda registrations solve almost every one of these issues we've seen. If you need to register something that provides configuration and then, later, use that configuration as part of a different registration - lambdas will be huge.
Consider intermediate interfaces like creating an IUsernameProvider that is backed by ISettingsReader<string>. The IUsernameProvider could be the lambda (resolve some settings, read a particular one, etc.) and then the downstream components could take an IUsernameProvider directly.
These sorts of questions are hard to answer because there are a lot of ways to work around having to build/rebuild/re-rebuild the container if you take advantage of things like lambdas and parameters - there's no "best practice" because it always depends on your app and your needs.
Me, personally, I will usually start with the lambda approach.
I want to make a tcp connection to a device and keep continously retrieve data from device. I want to start this with a simple request and keep it working background even Page response completed. Is this possible in asp.net?
Can a thread in ASP.NET work keep continue after Response.End?
Yes, you can if you do not care or do not need the result.
For example, in the following code, you call AddLogAsync and insert a log, but you not care whether insert successful or not.
public Task AddLogAsync(Log log)
{
return Task.Run(() => AddLog(log));
}
private void AddLog(TraceLog traceLog)
{
// Do something here.
}
I want to make a tcp connection to a device and keep continously
retrieve data from device. I want to start this with a simple request
and keep it working. Is this possible in asp.net?
I'm not really understanding above question. After Response.End, you cannot return anything, although you can continue work on something in different thread.
I am currently stuck and cant find any answers anywhere!! So any help at all would be great!
Currently Im trying to create a sharedObject on a client and send a string from the client containing information based on phone hardware(e.g. accelerometer and geolocation) to ams. From here I want to be able to access information from the sharedObject on the server in the main.asc to use elsewhere!
This is where the problem is occurring I cant access the shared object sent by the client. I sent my shared object like this:
//It's a best practice to always check for a successful NetConnection
protected function onNetStatus(event:NetStatusEvent):void
{
switch(event.info.code)//Check for a successful NetConnection
{
case "NetConnection.Connect.Success"://If the netConnection is a success#
so = SharedObject.getRemote("Data", nc.uri, false);//
so.connect(nc);//connect the sharedObject to the srever
so.addEventListener(SyncEvent.SYNC, syncHandler);//The sync listener
publishCamera(); //Publish the video
case "NetStream.Publish.Start"://If the netStream is a success
//etc
}
}
//It's a best practice to always check for a successful NetConnection
protected function syncHandler(event:SyncEvent):void
{
so.setProperty("username", nameForData);
so.setProperty("age", 21);
so.setProperty("nationality", "irish");
trace("Local"+so.data.username);
Im just not sure how to access so from server side!! I know this works as I have tested it but if there are better ways to implement it I would be glad to get advice!Below is proof that it is hitting the server
Update
Still stuck so I am adding a bounty and updating where I am and how I have progressed!
I have the information hitting the server(sometimes its not constant I dont know why)
Example is sometimes I get this in the admin console most times i have no information in the properties tab
What I am trying to do is to get the file to save every time I flush() the shared object so I can use it elsewhere
My server code is straight from the adobe api this is how it looks in the main asc:
in my onAppStart() I added these lines at the end:
application.allowDebug = true;
application.clearOnAppStop = false;
var Shared = SharedObject.get("Data", true);
trace("Name: "+Shared.name);
trace("Username: "+Shared.getProperty("username"));
in my onAppStop() I added these lines at the end:
var Shared = SharedObject.get("Data", true);
Shared.clear();
The serverside code for shared objects is (almost) the same as the client side.
So using so.getProperty(propertyName) should do the job.
If not check the server side shared object reference from adobe. Maybe that helps.
Hope i didn't missunderstand your question.
I have two issues here, the second one is irrelevant if the first one got answered, but still technically interesting in my opinion... I will try to be as clear as possible:
1st question: my goal is to fake a Server.Transfer in MVC, is there any descent way to do that, I found quite a few articles about it, but most where about redirecting / rerouting, which is not possible in my case (not that I can think of at least).
Here is the context, we have two versions of our website, a "desktop" one and a mobile one. Our marketing guy wants both versions of the home page to be served on the same url (because the SEO expert said so).
This sounds trivial and simple, and it kind of is in most cases, except... Our desktop site is a .NET 4.0 ASPX site, and our mobile site is MVC, both run in the same site (same project, same apppool, same app).
Because the desktop version represents about 95% of our traffic, this should be the default, and we want to "transfer" (hence same url) from the ASPX code behind to the MVC view only if user is on a mobile device or really wants to see the mobile version. As far as I saw so far, there is no easy way to do that (Server.Transfer only executes a new handler - hence page - if there is a physical file for it). Hence question has any one done that in a proper way so far?
And which brings me to:
2nd question: I did build my own transfer to MVC mechanism, but then figured out that a Response.End() does not actually ends the running thread anymore, does anyone have a clue why?
Obviously, I don't expect any answer out of the blue, so here is what I am doing:
in the page(s) which needs transfering to mobile, I do something like:
protected override void OnPreInit(EventArgs e) {
base.OnPreInit(e);
MobileUri = "/auto/intro/index"; // the MVC url to transfer to
//Identifies correct flow based on certain conditions 1-Desktop 2-Mobile
BrowserCheck.RedirectToMobileIfRequired(MobileUri);
}
and my actual TransferToMobile method called by RedirectToMobileIfRequired (I skipped the detection part as it is quite irrelevant) looks like:
/// <summary>
/// Does a transfer to the mobile (MVC) action. While keeping the same url.
/// </summary>
private static void TransferToMobile(string uri) {
var cUrl = HttpContext.Current.Request.Url;
// build an absolute url from relative uri passed as parameter
string url = String.Format("{0}://{1}/{2}", cUrl.Scheme, cUrl.Authority, uri.TrimStart('/'));
// fake a context for the mvc redirect (in order to read the routeData).
var fakeContext = new HttpContextWrapper(new HttpContext(new HttpRequest("", url, ""), HttpContext.Current.Response));
var routeData = RouteTable.Routes.GetRouteData(fakeContext);
// get the proper controller
IController ctrl = ControllerBuilder.Current.GetControllerFactory().CreateController(fakeContext.Request.RequestContext, (string)routeData.Values["controller"]);
// We still need to set routeData in the request context, as execute does not seem to use the passed route data.
HttpContext.Current.Request.RequestContext.RouteData.DataTokens["Area"] = routeData.DataTokens["Area"];
HttpContext.Current.Request.RequestContext.RouteData.Values["controller"] = routeData.Values["controller"];
HttpContext.Current.Request.RequestContext.RouteData.Values["action"] = routeData.Values["action"];
// Execute the MVC controller action
ctrl.Execute(new RequestContext(new HttpContextWrapper(HttpContext.Current), routeData));
if (ctrl is IDisposable) {
((IDisposable)ctrl).Dispose(); // does not help
}
// end the request.
HttpContext.Current.Response.End();
// fakeContext.Response.End(); // does not add anything
// HttpContext.Current.Response.Close(); // does not help
// fakeContext.Response.Close(); // does not help
// Thread.CurrentThread.Abort(); // causes infinite loading in FF
}
At this point, I would expect the Response.End() call to end the thread as well (and it does if I skip the whole faking the controller execution bit) but it doesn't.
I therefore suspect that either my faked context (was the only way I found to be able to passed my current context with a new url) or the controller prevents the thread to be killed.
fakeContext.Response is same as CurrentContext.Response, and the few attempts at ending the fake context's response or killing the thread didn't really help me.
Whatever code is running after the Response.End() will NOT actually be rendered to the client (which is a small victory), as the Response stream (and the connection, no "infinite loading" in the client) is being closed. But code is still running and that is no good (also obviously generates loads of errors when trying to write the ASPX page, write headers, etc.).
So any new lead would be more than welcome!
To sum it up:
- does anyone have a less hacky way to achieve sharing a ASPX page and a MVC view on the same url?
- if not, does anyone have a clue how I can ensure that my Response is really being ended?
Many thanks in advance!
Well,
for whoever is interested, I at least have answer to question 1 :).
When I first worked on that feature, I looked at the following (and very close) question:
How to simulate Server.Transfer in ASP.NET MVC?
And tried both the Transfer Method created by Stan (using httpHandler.ProcessRequest) and Server.TransferRequest methods. Both had desadvantages for me:
the first one does not work in IIS, (because I need to call that in a page, and that seems too late already).
the second one makes it terribly annoying for developers who all need to run their site in IIS (no biggy, but still...).
Seeing that my solution obviously wasn't optimal, I had to come back to the IIS solution, which seems to be the neatest for production environment.
This solution worked for a page and triggered an infinite loop on another one...
That's when I got pointed to what I had lazily discarded as not being the cause: our url redirect module. It uses Request.RawUrl to match a rule, and oh surprise, Server.TransferRequest keeps the original Request.RawUrl, while app.Request.Url.AbsolutePath will contain the transfered-to url. So basically our url rewrite module was always redirecting to the original requested which was trying to transfer to the new one, etc.
Changed that in the url rewriting module, and will hope that everything still works like a charm (obviously a lot of testing will follow such a change)...
In order to fix the developers issue, I chose to combine both solutions, which might make it a bit more of a risk for different behaviors between development and production, but that's what we have test servers for...
so here is my transfer method looks like in the end:
Once again this is meant to transfer from an ASPX page to a MVC action, from MVC to MVC you probably don't need anything that complex, as you can use a TransferResult or just return a different view, call another action, etc.
private static void Transfer(string url) {
if (HttpRuntime.UsingIntegratedPipeline) {
// IIS 7 integrated pipeline, does not work in VS dev server.
HttpContext.Current.Server.TransferRequest(url, true);
}
// for VS dev server, does not work in IIS
var cUrl = HttpContext.Current.Request.Url;
// Create URI builder
var uriBuilder = new UriBuilder(cUrl.Scheme, cUrl.Host, cUrl.Port, HttpContext.Current.Request.ApplicationPath);
// Add destination URI
uriBuilder.Path += url;
// Because UriBuilder escapes URI decode before passing as an argument
string path = HttpContext.Current.Server.UrlDecode(uriBuilder.Uri.PathAndQuery);
// Rewrite path
HttpContext.Current.RewritePath(path, true);
IHttpHandler httpHandler = new MvcHttpHandler();
// Process request
httpHandler.ProcessRequest(HttpContext.Current);
}
I haven't done much research, but here's what seems to be happening upon Response.End():
public void End()
{
if (this._context.IsInCancellablePeriod)
{
InternalSecurityPermissions.ControlThread.Assert();
Thread.CurrentThread.Abort(new HttpApplication.CancelModuleException(false));
}
else if (!this._flushing)
{
this.Flush();
this._ended = true;
if (this._context.ApplicationInstance != null)
{
this._context.ApplicationInstance.CompleteRequest();
}
}
}
That could at least provide the "Why" (_context.IsInCancellablePeriod). You could try to trace that using your favourite CLR decompiler.