Lock XML File When In Use?
Dec 6, 2006
I am using XML files to store some iformation that are to be processed. I use this code to interact with the XML file:
Dim xmlDoc As New XmlDocumentxmlDoc.Load("theXMLFile")
Do XML stuff such as add elements...
xmlDoc.DocumentElement.AppendChild(oAlarm)xmlDoc.Save("theXMLFile")
What I want to do is to lock the file so that no other process can use the file. If a process wants to use the file, I also want it to wait and try again until file is available.
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Aug 22, 2006
.NET 1.1VB 2003i have create a program where the program will dynamically create a mdb file, create a table, then populate the table via ADOX.dll using com interop.After populating the table i would like to FTP the said file to some FTP folder, to my dismay everytime i try to upload the mdb file i always get 0 kb, then i found out that the mdb file is "FILE-LOCKED" by some unknown process, but i dont know why because i have manually released all the resources that has been used, here is my code
[Code]...
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Jun 21, 2011
Dim bmi As New BitmapImage(New Uri(fiInfo.FullName, UriKind.Absolute))
bmi.CacheOption = BitmapCacheOption.OnLoad
this does not Use OnLoad
[code].....
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Jan 20, 2010
I've searched high and low for an answer so I'm hoping someone can help me out and I hope I explain what is happening ok. I have a number of people testing an application and one of them in particular is running into this error repeatedly. The error does not happen on my machine or almost any other. I know it is in relation to database usage but what I can't figure out is why the user only gets the error after the database has been called x number of times (and closed each time its done being used) as opposed to why the program doesn't crash the first time the database file is accessed.
The database is in MS Access and here's some pertinent info from the code - and the error is not subject to any particular database call...it just seems that after so many hits to the database its had enough and it crashes.
[Code]...
Like I said, why would the code work on almost all other machines (he's got a newer machine too and has tried both XP and Vista machines) and if there is something about his system why does is successfully call and use the database for awhile but then crashes out seemingly after a certain number of uses of the database file? I know it is not a specific call to the database because the area the application typically crashes for him at can be bypassed by changing some of the options available to the user - when he cuts back on the options used the program simply crashes at a later point in the process.
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May 21, 2010
Is there a way to lock a file without having to actually open the file and maintain a "connection" to it from my VB app? This should then prevent other users from writing/deleting/renaming the file. But I also want to allow only my app to write/delete/rename if need be.
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May 20, 2010
I am using Ms Access 2000 on a Windows Server 2008 and I have four users connected on a network to the server accessing the databases through a VB6 application which is loaded on all of the users' computers.While using the VB6 program i receive the error "Error 3050 Could not lock file".I know it has to do with the .ldb file.I have checked the permission and all users have full read/write/modify rights on the drive and the folder that the databases are stored in.I checked the MaxLocksPerFile and it is set to 9500.I even tried compacting and repairing and still this error persists.
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Dec 21, 2011
I have a .Net 4 WinForms app that generates a DLL, calls CreateObject on the generated DLL then calls one of several methods that the DLL contains. The DLL is eventually used by a separate app. This WinForms app is just to generate and test the DLL hence why it can generate the DLL multiple times.The problem lies in the fact that calling CreateObject on the DLL locks the file to the process. The next time the DLL is generated it can't overwrite the previous DLL file on disk without closing the app completely and starting it again.
I've tried Marshal.ReleaseComObject, executing the CreateObject in a separate AppDomain, even setting the variable holding the COM object to a different COM object via CreateObject, manually calling GC.Collect() and a whole host of other things but none result in unlocking the file.The code flow is basically (simplified and generic names, etc.):
...
' Compile and generate DLL that is COM enabled and works fine
...
Dim foo As Object = CreateObject("Bar.Foo")
[code]....
is there a way to release a file lock on a COM DLL that has been instantiated via CreateObject without killing the process?
Note: this is a continuation of this original issue. I now have the DLL registering without locking the file but now the issue is with the CreateObject call not the DLL registration.
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Feb 8, 2009
How would I Create a New .txt File & Lock it with a Password with VB8....?
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Mar 30, 2009
i'm getting this error: "File sharing lock count exceeded. Increase MaxLocksPerFile registry entry." i know i can manually go into the registry and edit this, but is there a way to do this in code?
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Apr 29, 2012
i have written a small app that:-Periodically captures a portion of a screen to jpeg file-Uploads this file to ftp serverAt first i used My.Computer.Network.UploadFileand it worked like a charm. Then i wanted to move to FtpWebRequest async. The reason was because i implemented a global keyboard hook and locking the main thread for upload, disabled my keyboard.I copied the example in MSDN regarding FtpWebRequest. the problem i have is that it seems that the file that is being uploaded is locke
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Mar 24, 2010
how I can lock a file so it will be completely written to by the first application, then unlocked for reading by my second web ticker app? My IDE is VB 2008. The second app has a ticker timer which I can modify accordingly. However, I'm still concerned whether the web app will encounter a situation where it competes for file access.
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Feb 17, 2012
I have difficulty in removing the LDB generated by the "CREATE" method of ADOX in the following code segment.Aims: Create (on the fly) a new access database and then export data (says Arena modules) to that newly created database.
Expected: The newly created access database should be able to be used by some external operations, say Access.exe, after the end of the subroutine and without exiting the current VB program.
1) I tested that the "Arena code" do nothing about the create/release of the ldb file.
2) I tested the "Exclusive Mode" in connection string, but the access file is still locked by the vb program.
3) I tested under both inside the VB environment, and directly invoke the generated from Explorer, and same results.
4) Other database formats is not the options to me. (due to Arena export limit)
5) It is not a web app.
Code:
Sub Method1()
Dim logs As New System.Collections.Generic.List(Of String)
Dim arenaApp As Arena.Application = Nothing
Try
[code]....
Platform:
Windows 7 64bit, Office 2010 (32)
VB 2010 express
Lib: MS ADO Ext. 2.8 for DDL and Security
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Oct 4, 2011
I am writing a program that acceses a file in VB/Visual Studio 2008 on Win7 and running it as a user who has admin credentials. I am opening the file with the following code:
Dim Input As New FileStream("C:FileTest est.txt", FileMode.Append, FileAccess.Write, FileShare.None) To test to make sure I can't access this file, I tried to open it with Notepad and I was able to and got no errors. I wrote a new value using Notepad and even saved it and I didn't get any errors form Notepad or my VB program.
I then went on and treid to open the same file twice from my VB program as:
Dim Input As New FileStream("C:FileTest est.txt", FileMode.Append, FileAccess.Write, FileShare.None)
Dim Input2 As New FileStream("C:FileTest est.txt", FileMode., FileAccess.Read, FileShare.None)
And I receivded an error in my VB program as expected. So the FileShare.None switch kind of works. Although I was still able to open the file with Notepad while my VB program had it open. I was aslo able to open Windows Explorer and reame it and even delte it while my VB program had it "open", in the write mode no less without my VB program knowing anything about it.
Why are other applications able to ignore the FileShare.None switch? Seems pretty useless if that's the case. And a huge secruity problem
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Jan 24, 2012
1. I have to create a file. 2. Then I want to write a string into the text file.
I can do part 1 no problem with: File.Create(strFilePath) But when I try part 2 to write to the file it won't allow this as it's still being used:
sw = File.AppendText(strFileName)
sw.WriteLine(strCode)
sw.Flush()
sw.Close()
My code in part 2 works fine on a file that hasn't just been created.
How do I release the file from the File object?
There doesn't seem to be a .close or .flush option.
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May 17, 2010
I would like to know if there is any opportunity in VB.Net to use atomic operations. Or Maybe there is an opportunity to check if a file is allready in use or opened.The reason why I ask is because I got a little application that I would like to log its actions. As the applications uses threads the method for writing the log file sometimes is trying to open the log-file more than once which leads to an exception.
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Dec 15, 2011
i want to create an exe in vb.net by packaging few perl files along with it. when i am packaging those files i am able to hide those files by making the hide option true. but if the 'show hidden files' is selected those files will be visible. I want to lock/prevent the user from opening the perl file/code. want to know if there is any way to do it.
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Jun 18, 2009
I wanna load XML file with XDocument.Load method and lock it. How to do it?
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May 8, 2009
We needed an inter-process reader/writer lock.We decided to use a file and lock the first byte using LockEx and UnlockEx. The class creates a file in the system temp folder when it is created. The file is created with readwrite access and share read|write|delete.We also specify DeleteOnClose so we don't leave loads of temp files laying around. Obviously AcquireReader and AcquireWriter call LockEx with appropriate flags and ReleaseLock calls UnlockEx.We have tested this class using a small application that you can run several instances of and it works perfectly. The application that uses it has a problem, which we have managed to re-produce in another small test app. In pseudo code it is
Create InterProcessReaderWriter
Dispose InterProcessReaderWriter without acquiring any locks
Launch a child process which takes a reader lock
The first time this runs, it works fine. If you attempt to run it again, while the child process from the first time is still holding the lock, we get an UnauthorisedAccessException when trying to open the file.This appears to be a permission issue, not a sharing violation but all the processes in this test case are running as the same user.
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Aug 1, 2011
lock from reading/writing/copying a loaded XML file with XDocument.Load [VB 2010]?
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Sep 29, 2010
I am getting the below error when I click a row in the grid. But this error is raised only in exe, which is installed in client machine, but when I check the same from source code in my machine, i am not getting this error. I am able to locate the record.
[Code]...
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May 27, 2009
Is there analogue of lock statement from c# in vb.net?
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Jan 23, 2009
Basically,I had a button in my form1,when I click it,then form2 will be display...Now I would like to lock form2 until a button in form2 had been clicked,then only I can do anything in other forms...I means form2 must be closed before I can remain to form1.
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Dec 15, 2011
VB.net how to lock a computer screen using a form
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Aug 23, 2010
How do I lock a row in MySQL and then only allow the app that locked it to change the values of that row?
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Dec 28, 2009
Wrote this code:
Function ReadRegistry(ByVal regType As String, ByVal RegPath As String, ByVal KeyName As String)
Dim regKey As RegistryKey
[Code].....
What I want to do is raise an error if I get passed a value that isn't listed in the case statement.. or it there a way to define it better?
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Sep 25, 2009
I have a form and its filled from a VIEW of two tables on SQL server. When its opened i dont want other users opening that customers details from either table.I know SQL itself prevents writes if its opened but i want to stop people opening the record in the first place.[code]...
I then tried writing these values to the db on the form loading but it doesent work - it just sends back NULLs. I tried the same code in the on load event into a button and it works fine there. So im thinking i should do this as a Trigger on SQL itself, but im unsure how i could get the users computername or Windows Login name, or even username from the front end im building.
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Aug 7, 2007
how to lock PC using VB.net? So that any user cannot do anything on my PC?
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Oct 14, 2010
But not my application.A app i use refuses to be brought forward, so wondered if there was a way for a vb app to run in the bg that can force a specified application to stay on top, & even maybe set its screen position and lock it there???
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Mar 20, 2012
In my project i am using begin transaction commit or rollback changes. but this causes lock to the tables in that particular functionality.
So if the any other user does any other functionality those locked table are not available until the transaction is completed. I want to know if there is any alternative to transaction which insures data security but the tables are not locked out.
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Mar 29, 2011
how would i bypass the loader lock. I know there is a way to disable it but im not sure how
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