Say I have a rolling collection of values where I specify the size of the collection and any time a new value is added, any old values beyond this specified size are dropped off.Obviously (and I've tested this) the best type of collection to use for this behavior is a Queue:
myQueue.Enqueue(newValue)
If myQueue.Count > specifiedSize Then myQueue.Dequeue()
[code].....
I need to create a notification system for my application that will alert the user once new items have been sent to their queue, which is made of up database entries. The latter part of this question may need to be asked in the database forum, but I guess we'll figure that out First, since I haven't created anything like this before, I need some direction on what the best possible solution would be.The notification system should always be running and work independently of the main app. With this requirement, I thought a Windows Service would be best.
The notification itself will just be a quick form that alerts the user. I'm sure most of that will be fairly easy to create. The only issue I'm wondering about is how to constantly check the database and determine a new record has been inserted.Would a windows service have a timer or something that allows me to constantly check?If it does, how would I determine a new record has been inserted?
I am using Visual Basic 2010 Express. I have 2 forms. A main form which does all the grunt work and then a small supporting form to get some additional user inputs.
Some program background...I am developing a program to characterize solid rocket motors based on test stand data for a hobby project. I load the time, thrust data into lists via a streamreader from a text box.
However, since the data is raw I would like for the user to select the "start" and "end" of the burn. I am currently trying to do it right after I load the data. As I read the data in, I just put it in the listbox of the supporting form as well. My main issue is, I need two values from the user. A start and end time. the index would probably be easiest, as I will rewrite the data list based on the time increment and delete everything before the first listbox selection and everything after the second selection. I can't get the values from the main form. I have exhaustively searched the internet trying to find something that I can apply. If someone could help with a framework on how to do this.
I understand how to get text from this text box on a different form, but this deals in variables and maybe setting up a class? I am having trouble communicating between the two forms.
I have a form that has a queue and i want to transfer that queue to another queue in another form. however when i try to use the elements in the second queue after transfer, I get the error message queue empty!below is my code
First Form
Imports System.Collections.Generic
Public Class Form1
[code].....
I have an array that I'm basically treating like a queue (FIFO)I'm trying to decide the fastest way to implement this.Currently I'm just iterating through and shifting everything up an element and placing the new data @ 0. This was fine when I was dealing with 1000 element arrays, but now I'm moving up to 100k element arrays and it's stalling my code.It has been useful to have the data in array form because I'm using the array.sort method and a few other statistical modifications that use the element number (of the sorted list) to work.I'm not sure if VB lists are (like Java) pointer based, and if so I think that shifting pointers would execute faster than my current approach.My question is, if I did move to a list would it a) be faster, and b) is there a way to call a quick sort from the list class?If the execution time is the same for the array vs. list is there a better way to make a FIFO structure in VB?
View 2 Replieshow "peek" really operates or something but what I'm trying to do is have 2 separate audio files play one after the other over and over again.I was expecting that I would hear wav1 and wav2 alternate but I only hear wav1 on each cycle.Doesn't peek use the first data then push it to the back without discarding it?Therefore wav2 would be next in line to be played? [code]
View 14 RepliesHas anyone seen a .net email queue? I want to be able to specify the SMTP server to send via, report problems and retry emails if necessary or requested.
View 2 RepliesHow can I clear the printer queue from VB? if I was doing it manually I would stop spooler service, empty the windowssystem32spoolprinters folder and restart the service
View 8 RepliesWhat is the difference between a queue(of t) and list(of t)? I've been working a lot with list(of t), but up until recently I haven't even heard of queue(of t). I know that they are both general list.
View 3 RepliesI am currently creating a FTPWebrequest to handle my uploading (the webrequest section of my function is below). At the moment my code loops through this webrequest section for each file - giving the file path of each file in the string "CompleteLocalPath". For each file it creates a webrequest and giving the required file path, uploading the file using a file stream, and then closing the stream. This works, but seems to take quite a long time. Can you recommend a more efficient way? Perhaps by using one webrequest but modifying the upload path?
[Code]....
I have a program that is using API's to send mouse events and keyboard events to another application that is running. I need to know how to tell if there are any messages left to process for that window after I have click on a button or moved to the next field. I need to know this so I don't send any more mouse or keyboard events until it has finishing processing everything in its message queue. An example is that I click out of the key field and the form has to go out and read a client record. This may take a second or two, so I need to wait until the form is ready for more input.
View 2 RepliesThe below code (VB 2008) will check the print queue every milisecond for a job. It will then show the pagecount in a text box. It works great when im printing to a local printer, but As soon as I change my pc default printer to a network printer, I cant capture any data.
View 1 RepliesI'm looking for a way to move a printjob from a paused printer to another printer. I have looked at the new name space System.printing in .Net framework 3.X.Is there a way to do it in .NET?An externa application creates a printjob.I catch the event "a printjob add" in the printqueue.I pause the printjob.Now I want to move the printjob to another printerIs there a way to do it in .NET?
View 13 RepliesWe have made code for writing to and from a IBM message queue.Writin goes well, but reading gives an error, see bold text
[Code]...
I would like to develop a queue application in VB for a clinic, so that when a patient comes, he is entered in a queue as he waits. A doctor picks the next available patient in the queue and a message is posted in the screen for that patient to go to the doctors room. How do i do this?
View 21 RepliesHow do I (i) sort the array of type FileInfo returned by the DirectoryInfo.GetFiles method by (file) CreationTime in descending order and (ii) once the array is sorted efficiently load it or convert into a Queue object (of type FileInfo) for subsequent processing. I thought of using the queue object as it handles things on a FIFO out basis and I'll be adding to the queue as new files arrive.
View 4 RepliesI have question about the firing of events in vb. Lets say if I have timer that fires every 10 seconds and then I also have eventhandler that is listening to some other event (like message arrived in queue and now event fires to process it). Then how does vb handles them if the program is currently processing Timer1 and message arrive event fires or vice versa? Does it complete the current processing and then jump to the next event or just switch in the middle to the new event and then finishes that and then resumes back to the first one?
View 6 RepliesI'm developing an application to monitor print queue and pause it to check some conditions, then resume or cancel print job. I can get total pages for printing document but can't get number of copies, how can i get this parameter.
Ex. If someone print 5 pages document for 2 copies, the total pages i got is 5 not 10 pages. (how can i get the real total pages)
I am working on fax component that manage some operation of XP fax service by using VB.Net and using FXSCOMEXLIB.DLL, I want to register events by fax queue status (job added, changed, removed, ... etc.), I am reading the article on this link: [URL] but the events not work (not called).
View 6 Repliescan i remove an item from the middle of a queue?
View 1 RepliesHow do i return a value from a function that i can copy to a queue?I imagine that value must also be a queue.
View 4 RepliesIm a newcomer for Sonic JSM queue. I need to send an xml message to a JSM queue. I can send a string message using following code.Dim msg As Sonic.Jms.TextMessage = SonicSendSession.createTextMessage()
msg.setText(ESBMessage)
msg.setStringProperty("instance", Header)
SonicSender.send(msg, Sonic.Jms.DeliveryMode.PERSISTENT, Sonic.Jms.DefaultMessageProperties.DEFAULT_PRIORITY, MESSAGE_LIFESPAN)
[Code]...
I have a form that has a queue and I want to transfer the data of that queue to another queue in another form. however when i try to use the elements in the second queue after transfer, I get the error message queue empty!
Below is my code
First form
Imports System.Collections.Generic
Public Class Form1
Dim wait As New Queue(Of String)
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[Code] .....
I expected the recieveQueue function to copy the queue passed to it into the waiting queue, then it allows me to use the waiting queue contents as I want. But when I try to use it, around this line I get the error, 'queue empty' < If waiting.Count > 0 And waiting.Peek <> "" Then >
I am currently going through Murachs Beginning vb.NET and have come across an problem with one of the exercises at the end of the chapter on collections. I basically have to update a simple Invoice application that was developed in an earlier chapter.It requires me to update the app such that everytime a new invoice object is created ( via pressing the new invoice button) this object is added to a queue. I am ok with this part.However I then have to edit the exit procedure so that the invoice objects are dequeued and displayed in a message box. This is where I am having my trouble. My code so far is shown below. This consists of the form.vb and the and the Invoice class.[code]I have also added a diagram of the format for the message displayed in the message box. I know I have to iterate through the queue but how can display the invoice customer name and invoice total?
View 4 RepliesI'm trying to Enqueue several processes to a queue of processes.When I do, each process is added, but only the last process name is added. The rest of the names are blank.Here's what I'm doing to test it:
VB.NET
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
[code]......
I've passed object sucessfully to threads in the past but I'm stumped on this one:-
HTML
Public Class TileDownload
Structure RequiredTileDetails
Public MapID As String
[Code].....
Ok say I have this Dim MyQueueOfClients as new Queue (Of TcpClient) I also have two threads.
In thread one a TcpListener waits for connections then adds a connected TcpClient to MyQueueOfClients.
MyQueueOfClients.Enqueue (TcpClient)In thread two I then check to see if there are any Clients in MyQueueOfClients. If so I then remove them from the MyQueueOfClients.
MyTcpClient = MyQueueOfClients.Dequeue I think the question Im asking is this thread safe?
Can I Enqueue and Dequeue at the same time from different threads?
Well it helps if you read everything. I have just read this as well
A Queue(Of T) can support multiple readers concurrently, as long as the collection is not modified. Even so, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.
As the title says can I create a memorystream then use it in a FIFO manner like a Queue.When you use memorystream.write it writes data at the memorystream.postion.If I then want to read the beginning of the memory stream I have to set position to the beginning and do a memorystream.read.
View 4 RepliesI'm receiving tons of statistics data that I need to insert into the db.I would like to implement some kind of Queue or FIFO class that keeps all the dataand when it reaches to a specific count (buffer), it will send that data to the SQL through bulk insert. This should be thread-safe.
View 3 RepliesI am processing a local message queue and every now and then getting an "Insufficient resources to perform operation" error message when there is over 2GB RAM free.The queue is very small (often only a couple of items (if that) and never exceeds 50 items), with the items themselves being just a very basic class that consists of a filename (as a string), two integers, two booleans and one enum (i.e. very little actual data)In order to check the size of the message queue, I have a timer that ticks every 5 seconds, and when it does calls the following code:
Private Function GetQueueLength() As Integer
Dim QueueLength As Message() = ProcessQueue.GetAllMessages
Dim Length As Integer = QueueLength.Length[code].....