I have been trying to figure this our for far too long and I cannot get my head around it. Every example I have seen seems to be far more complex that I need. I have a web service in my project (.asmx). I want to call it very simply from a button on a webpage.
Click
Run service asynchronously
return control back to webpage (web
service running in background)
I have this code obtaining data from a sensor that is sending a string that contains 4 numbers separated by a tab and terminated by an end of line/ I am trying to use an asynchronous callback to get the data over TCP. That problem is that the callback function is not grabbing the complete string. Sometimes it will, other times it gets half in one retrieve and half in another. I need the callback to hold off until it gets a newline character.
Code:
Public Sub readVaisala()
Dim ip As String = "192.168.1.30"
Dim portNumber As Integer = 23
Dim time As Int32 = Now.Second * 1000 + Now.Millisecond
[code].....
I have a class with a mthod which does a a time consuming task. I know how to start the method in a separate thread using the Threading.Thread class. What I want to do is use callback so as to have the method report its result to another method when completed. I chose to use the asynchronous Begin/End call pattern.
Private Function BeginConnect(ByVal URl As String, ByVal callback As AsyncCallback, ByVal state As Object) As IAsyncResult
'Some Code
End Function
[code]....
I have a class with a mthod which does a a time consuming task. I know how to start the method in a separate thread using the Threading.Thread class. What I want to do is use callback so as to have the method report its result to another method when completed. I chose to use the asynchronous Begin/End call pattern.
My thoughts are:
Private Function BeginConnect(ByVal URl As String, ByVal callback As AsyncCallback, ByVal state As Object) As IAsyncResult
'Some Code
[Code].....
How can I set up an asynchronous web service in asp.net?
I want to call a webservice to post some data to a database, but I don't care if the response failed or succeeded.
I can use .net 2.0 or 3.5 only and it can be in vb or c#.
I just have a simple vb.net website that need to call a Sub that performs a very long task that works with syncing up some directories in the filesystem (details not important).
When I call the method, it eventually times out on the website waiting for the sub routine to complete. However, even though the website times out, the routine eventually completes it's task and all the directories end up as they should.
I want to just prevent the timeout so I'd like to just call the Sub asynchronously. I do not need (or even want) and callback/confirmation that it ran successfully.[code]...
I'm using ASMX web services in VB.Net in VS 2005. I am calling a function method on the web service that returns a true or false value. This works fine if I call the the web method synchronously, but if I want to call the method asynchronously, the function returns to a sub and there is no return value; therefore, I can't tell whether the result of call is true or false. Is there a way to make an asynchronous call and still get the true or false result (perhaps using the userState Object)?
For Example:
Dim MyResult as Boolean = MyService.GetResult(10)
Dim MyResult as Boolean = MyServer.GetResultAsync(10)
This doesn't work the compiler complains: "Expression Does Not Produce a Value"
I'm trying to get data with the methods below and I get null response and can't figure out why. I'm just trying out a different way of using a wcf service from silverlight and I don't understand something that I should.[code]...
The employee object will stay null. If I put a break into the service call and follow through the code it finds the correct record from the database and the return statement shows an object with the correct data but still the employee object in silverlight side will remain null.
I have a (very) simple WCF written in VB which I can build and publish locally to IIS. Works great.
What I need to do is (somehow) deploy it to a different server which does not have IIS. It's supposed to be run as a windows service.
how to do this. All directions on MSDN seem to be for VS 2010 (we're using 2008).
Just trying to execute commands in cmd.exe just a simple Net Stop [service] and get a error 5. I want it to run cmd in administrator mode. One way I have seen that you can by holding down ctrl & shift while clicking cmd.exe?
View 26 RepliesI am currently writing a program in Visual Basic 2008 express edition to read and write to tags on an Omron PLC. I am using the DeviceXPlorer OPC Server V4.1.1.1 program to connect to the Omron PLC. I have made two programs, one is a form program which works fine, two is a windows service program where it does not let me connect to the OPC Server. The connection code is identical, the only difference is the windows service code is called by a timer. The timer works fines and jumps into the connection code, but stops at the line
[Code]...
i have a Windows service that is hosting a WCF service through net.tcp and this is working great. I have also created a WCF service application. I am trying to add the net.tcp service reference to the service application. Then I add it to the GAC that goes ok but if I try to RegAsm the WCF service application to allow it to be called from Server.CreateObject I get the error:
Warning: Type library exporter encountered a type that derives from a
generic class and is not marked as
[ClassInterface(ClassInterfaceType.None)]. Class interfaces cannot be
exposed for such types. Consider marking the type with
[ClassInterface(ClassInterfaceType.None)] and exposing an explicit
interface as the default interface to COM using the
ComDefaultInterface attribute.
It does not work. I have tried to call it through a class library but this does not work either as the end point is not set correctly.
I'm a rookie in Visual Basics 2008 and i am trying to make a program to communicate and read tags from an Omron PLC. I am trying to connect to the PLC via devicexplorer opc server, because it can let me read DInts and Reals from the PLC tags. I have referenced Microsoft ActiveX Datas Objects 2.5 Library and OPC DA Automation Wrapper 2.02. I have made some code which connects to the PLC "in a form", but I cannot use the same code and connect through as a Windows Service program.Here is my code,
Public Sub OpcConnect(ByRef Items() As String, ByVal PLCType As Integer)
Dim j As Integer
Dim TempSvrHandles As Array[code].....
Note: this code is run in a timer on the windows service, it connects properly to the "RSLinx OPC Server", but "Takebishi. Dxp.1" (devicexplorer shortcut) exits the sub routine at MyServer.Connect(PLCServer) ' connect to the opc server.
I have a VB2008 application which can control a windows service i.e. start, stop, pause etc. This runs ok on a Windows XP machine but not on a Win 7 machine (message is - Service error cannot open <service name> service on computer '.') ( if I stop the UAC then it runs ok ). It seems to be a rights issue,
View 3 RepliesIs there anyone can post a simple code using vb,that start building a simple games ?
View 2 RepliesI'm trying to use a .DLL which Callbacks a Function of my project, but I can't get it to work.
Declaration from .h file of .DLL
void DLL_EXPORT SetEntity_CallBack(bool Active, _
void (*Entity_Callback)(int Site, int Application, int ID, _
[Code].....
I have a small VB.NET application built using VS 2008 and .NET 3.5.Very simply, there is a timer that kicks off every few seconds to download an XML stream from the web. I look at this stream and manipulate it.The problem I am facing is that the remote web server may not respond in a timely fashion to the following line of
[code]...
How can I implement asynchronous calls so that the my application can behave without locking up?
i'm creating an Asynchronous socket programming in vb.net. i've utilised the code from Asynchronous client and server code frtom the following links:m a new user so could post only one link fully)When I try to connect the for more than one client the second client always waits until the first clientcompletes the call. i want the clients to accept calls at the same time
View 1 RepliesI am writing web services with VB.NET (2.0). The client side will use different technologies such as Java and Siebel. So, if I write asynchronous web services, is it possible for different platforms to consume them? I know it is quite easy with a consumer having .NET platform, but not sure for different platforms. Is it enough for them to have asynchronous ability, or should it be a similar platform?
View 3 RepliesI noticed that HttpWebRequest freezes the UI while it's waiting for a web page to be downloaded:
[code]
If someone's done this before, what is a good way to keep the application responsive?
I am using a BackgroundWorker, an OleDBDataReader, a DataGridView to retrieve records asynchronously from an Access database. I call ProgressChanged event from the DoWork event every time I retrieve a record. In ProgressChanged event I add that record to the DataGridView and also update a label. There are about 2000 records to retrieve.I have two problems:Although I'm running an asynchronous operation, the UI remains unresponsive unless I use Thread.Sleep() inside the DoWork event (Why?). Using Sleep() method with an argument of 1 causes the process to run 20 times slower! (Process takes about 1 second if I comment out the 'Threading.Thread.Sleep(1)' line, compared to 20 seconds if I use it.) What can I do to get a responsive UI and a fast background operation (at least not 20 times slower!)?The other problem I am facing is: if I close the form while the asynchronous operation is ongoing, I get this exception (I think in the ProgressChanged event): Exception has been thrown by the target of an invocation. I tried using FormClosing event to end the process but no luck. How to fix this?
View 5 RepliesI have a C++ dll that contains a callback. The callback has one parameter that is passed in and one parameter that is passed out. The parameter that is passed from C++ is a variant. So, we are going from a variant in C++ to an object in VB.NET. The function works. However, It seems that there is a memory leak on the VB.Net side. This must be a Marshaling issue. I have tried to use the MarshalAs Functions, but to no avail.
VB.NET
Declare
Function EnableWriteNotification
Lib
[code]....
there is error when i use callback function A callback was made on a garbage collected delegate of type 'skynet1!skynet1.Form1+myCallBack::Invoke'. This may cause application crashes, corruption and data loss. When passing delegates to unmanaged code, they must be kept alive by the managed application until it is guaranteed that they will never be called.
View 6 RepliesI am working on a Twitter application and with the authentication process, Twitter returns Two Tokens with a Callback URL, For example: [URL]. How do I extract each token and put them into separate strings?
View 5 RepliesI am writing classes in VB.Net (both managed). The main class "A" creates an instance of "B". Class "B" must call a method of Class "A". I need to know two things (syntax, etc...):
1. How does class "A" tell class "B" what method to call?
2. How does class "B" call the method?
The method must pass back an array of Shorts (in this particular example), either as a return value, or as a ByRef argument.I don't want to use an event if I don't have to. The execution is timing critical. (I assume event handling involves a lot of overhead by the operating system, but I may be wrong.)
I made a TCP server which communicates with multiple clients at once, but I can't seem to be able to make them stable. When one of the client sends 100 packets to the server, the server receives only a few of them.Here's the client code in PasteBin. It shows how the client connects to the server and then sends 100 messages in a For loop to the server.And here's how the server handles the connection. I couldn't paste the full source as it's hundreds of lines long so let me know if it's missing any mandatory parts and I'll upload them as well.
View 1 RepliesI create an automatic ftp file downloader by using FTPwebrequest. In which, is there any possible to download multiple files simultaneously using Asynchrounous and threading concept?
View 1 RepliesI'm using asynchronous to send/receive from a website I want to block the BeginGetRequestStream method which I have done, using
Code:
WaitEvent.WaitOne(1000 * 20, false);
the problem is that it blocks the UI, which I thought it did not so it basically works like GetRequestStream which does block the UI.
I basically have a few thousand transactions 7,000 - 10,000 transactions to process over a short time. The flow goes like this.
---> ----> ---> ---> receive (1000) as each transaction takes approx 2 seconds so if i were to process synchronously it would take all night......
Now first i would like to ask if i am going about this the right way ? the service i am communicating with is not .net but is built to handle large amounts of requests. I have obtained the following code that suggests it will do what i am after
dim strxmlreq as string = '(this is where i input my xml string)
Dim request As HttpWebRequest
' Create the request
[CODE]...
The problem i have is if the above will work for me where exactly do i catch the returned xml string ? I assumed "result" would be the xml output string.
Download file asynchronous using sockets
View 8 Replies