I'm working on a problem using two signalR Hubs, when I close the navigator window (or tab) only one OnDisconnected is called.
Example pseudo-code:
Hub1{ ... OnDisconnected(){print(1)} }
Hub2{ ... OnDisconnected(){print(2)} }
on window close the output is:
1
Can someone explain me why?
Thank you.
Do you have any client methods attached to Hub2? If not, I think the client will just ignore it and only connect to Hub1.
Related
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 using an http service object to make servlet requests inside a method in flex. The method is being invoked simultaneously in parallel by two events. I could see that both requests have reached the servlet, but only one returns to the result event. Also this behaviours is not consistent . is it possible that parallel invocation of the httpservice result in loss of some requests? I am sure that both requests have reached the servlet and data is returned from it. Its just that the result event is not triggered in certain cases.
Thanks in advance.
Including code to describe the issue better.
Please find the method below. The below method "callServlet" is being invoked by two separate events
private var httpObj:HTTPService=new HTTPService();
private function callServlet(text:String):void{
Alert.show(text);
httpObj = new HTTPService();
httpObj.url=<servlet URL>;
httpObj.method="POST";
httpObj.resultFormat="xml";
httpObj.contentType="application/xml";
var requestString:String=text;
httpObj.request=requestString;
httpObj.addEventListener(ResultEvent.RESULT,onResultMethods);
httpObj.addEventListener(FaultEvent.FAULT,onFaultMethod);
httpObj.send();
}
Each time i call the method, i pass a different "text" variable. I can see that the alert displays the two different texts send to it. And as explained earlier, both requests does reach the servlet and a response is sent from servlet.
But the result event "onResultMethod" is invoked just once.It doesnt invoke the "faultonFaultMethod" either.
Yes, I have seen this problem before, if you are making multiple requests from flex, some of them will be lost, that was back in 3.0 times. Browsers has a way of stopping the number of http calls, they can allow maximum of 2 calls at a time(depends on the browser), may be chain your requests one after the other or use a singleton which manages your calls.
Thanks all for help. I think i ve got the issue though i cannot guarantee the answer to be right.
The above method is called twice by two events. The httpOject variable is a private var global to the method callServlet. The listeners created in this method are being removed in the result and fault handler methods(this is not shown in the code above).
So i believe when multiple events call the method simultaneously there is a chance that the global variable httpObj is modified by both the events and hence both events result in servlet call using the same httpservice object. When the first call returns to the resulthandler i am removing the listener for resulthandler due to which the second result does not reach the resulthandler method.
This is my assumption and as of now i dont have any better solution. Do let me know if anyone comes up with a better explanation.
In my AIR application (with mate-Framework) i did follwing things:
click on a button
call a method in my model "onApplicationBusy"
apply some filter in arraycollections.
In my onApplicationBusy there is this code:
FlexGlobals.topLevelApplication.enabled = false;
FlexGlobals.topLevelApplication.
I trace every step and all methods are called in right order.
But my application never becomes disabled.
Why. Is there a method for this purpose.
I try InvalidateDisplayList or ValidateNow or callLater. But all tries won't work. Probably i try it on the wrong place?
I assume, my application is so busy while applying filters (4 values for 10.000 lines) that the disabled property can't processed.
If i call the method without applying the filters all works fine.
If i call just the disbaled property but never enable the app again, the app will shown as disabled after applying the filters. for me too late.
What i origin want is a clear behavior, when the app is busy and when not (ready for clicking on buttons and all this stuff).
If you can help me or know a method, how can i shown a busy application, please help me
Thanks
Frank
All right, the setTimeout Method solve my issue. I assume, I have to wait for the next screen refresh.
Why callLater won't work and when i have to implement those functions, because i have too less ressources while my filterFunction is running?
Frank
I'm using FlexGlobals.topLevelApplication.stage.mouseChildren = false | true;
Worth noting that I first tried setting the mouseEnabled flag but found various visual elements would not update at all while mouseEnabled = false.
I am using MVVM Light and am using Messages to communicate between ViewModels to let a ViewModel know when it is ok to execute something. My problem is that I register for a message and then it receives it multiple times. so to keep from my program executing something more than once I have to create boolean flags to see if it has already been recieved. Any idea why it does this and how I can stop it?
Make sure you unregister your message handlers once you do not need them anymore. The Messenger keeps a reference to the registered methods and this prevents them from being garbage collected.
Therefore, for ViewModels: make sure that you call Cleanup once you done (or implement IDisposable and call Cleanup from there).
For Views (Controls, Windows, or similar) call Messenger.Unregister in an event that occurs on the teardown of the view, e.g. the Unloaded event.
This is a known behaviour of the MVVM and has been discussed in several places.
Very old question but I solved the problem by doing this:
static bool isRegistered = false;
and then, in the constructor:
if( !isRegistered )
{
Messenger.Default.Register<MyMessage>(this, OnMessageReceived);
isRegisterd = true;
}
I have seen this issue before. It had to do with the Messenger.Default.Register being called more than once. The MVVMLight Messenger class will register the same item 'x' number of times. This is why when you call the Send you get it many times.
Anyone know how to prevent MVVMLight from registering multiple times?
really old but thought I would answer just in case somebody needs it. I was fairly new to silverlight at the time and the issue ended up being a memory leak as the viewModel, which had multiple instances, was still in memory.
As other contributors mentioned, the same message is being registered multiple times. I have noticed this behavior taking place while navigating to View X then navigating back to View Z where the message is registered in the constructor of the Z ViewModel. One solution is to set the NavigationCacheMode property to Required
<Page
........
........
NavigationCacheMode="Required">
Is there a way to make synchronous calls using RemoteObject in Flex?
All IO in Flex is asynchronous. The typical pattern to deal with this is to use an AsyncResponder. For instance:
var t:AsyncToken = remoteObject.methodCall();
t.addResponder(new AsyncResponder(resultEvent, faultEvent));
think twice when u want it to be synchronous.
Do u know what synchronous mean? it will FREEZE your application until it receive data. Unless u are pretty sure that your remote calling can receive return value immediately (super fast network connection).
if your function call depends on each other, i would suggest you implement a state machine. e.g.
after 1st async call, your state becomes STATE_1, and your next function call will check on this state variable, to decide next move (ignore the current call or carry on).
my 2 cents.
If you want synchronous behavior, just add a wait after you make the call.
EDIT: I've added code for the chaining behavior I was talking about. Just replace the result handler each subsequent time you call the remoteObject.
...
remoteObject.function1(...);
...
private var resultHandler1(event:ResultEvent):void
{
...
remoteObject.removeEventListener(resultHandler1);
remoteObject.addEventListener(ResultEvent.RESULT, resultHandler2);
remoteObject.function2(...);
}
private var resultHandler2(event:ResultEvent):void
{
...
}
I achieved the same in two ways: First, as said above the use of state machines. It may get tricky at times. Second, the use of command queues - I think this is the best way to do it... but the downside is that the UI may not be very reflective in this time.
you should perhaps try and make one request with with all the data u want to be recieved synchronous and then make the different classes that need data listen to the correct data for that class.
ex:
// request
remoteobject.GetData();
// on received request
private function receivedData(evt:ResultEvent):void
{
for each (var resultobject:ResultObjectVO in evt.result)
{
var eventModel:Object;
var event:DataEvents = new DataEvents(resultobject.ResultType);
event.data = eventModel;
eventdispatcher.dispatchEvent(event);
}
}
Something like this. Hopes this helps.
No, why would you wish to do that anyway.
Flex makes things asynchronous so that the user isn't forced to sit and wait while data is coming back.
It would be a very poor user expereince if each time an app requested data the user had to wait on it coming back before anything else could happen.
from comment
No you don't need synchronus behaivour. If you're making say 2 calls and call 2 comes in before call 1, but 2 relies on the data inside 1 then you're left with either don't fire off event 2 till 1 comes back (this will slow down your app - much like synchronus events) or implement a way to check that event 1 has come back in event 2's handler (there are many ways you could do this).
If you're firing off many events then why not have a wrapper class of some description that tracks your events and doesn't do anything on the responses until all events are back.
You can use the AsyncToken to keep track of individual requests, so if you are firing of loads at once then you can find out exaclty whats come back and whats not.
You all are somehow mistaken or not using flex from adobe, if you send 2 calls to the server, no matter if each has an individual resquestObject the second one will ONLY be returned after the first one finish, even if the second one takes 1 milisecond to process. Just try the fibonnaci 1/40 example.
Maybe if you call a synchronous XMLHttpRequest calling JavaScript on Flex, you can do this.