Communications :: Program Stalling On Network Reading?
Oct 8, 2008
I am playing with network sockets as I need to work on a client-server application. So I have tried this simple code from VS help:
Code:
Dim tcpClient As New TcpClient()
'The following line do not belongs to original code 'But I needed to add it as debugger told me that 'I couldnt getStream from closed sockets
tcpClient.Connect("127.0.0.1", 8000)
Dim netStream As NetworkStream = tcpClient.GetStream()
If netStream.CanWrite Then
[code]....
So, I supposed that the code above would write the message to the loopback IP (127.0.0.1), it would be kept in the network buffer and would be spited out when it readed the same loopback IP. However, when it gets the line whre it should read the stream, the program just stalls and keep reading it forever. I have tested the stream with as if it was just awaiting for something to read. I have tested the stream with getStream.DataAvailable and it returned me False, what makes me guess that the data is NOT being properly written to the IP.
Firstly I thought that it could be something with the loopback IP, then I tried to provide the machine local IP (192.168.2.25) but I got the same behavior: code stalls...
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Jul 4, 2008
I am trying to write a program to ping computers on my network to see if they are turned on. So far i have the following:
Code:
If My.Computer.Network.Ping("192.68.0.5") Then
MsgBox("Computer is on.")
Else
MsgBox("Ping request timed out.")
End If
If i use ip addresses, this works fine but i would rather use hostnames due to the ip addresses being dynamic (something which is outside my control). Using the hostname, it reurns "Computer is on" if the ping is successful, but if the hostname cannot be found, instead on returning "Ping request timed out", an error occurs as follows:
A first chance exception of type 'System.Net.NetworkInformation.PingException' occurred in System.dll
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Jul 31, 2008
I would like to know how is it possible to send data over the network using VB 2005 .... ! It must be capable of being the type of sending short text over the network just like chatting
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Feb 6, 2009
I have a small embedded web server and to setup its network parameters I use a serial port, however this is giving me a lot of trouble due to USB to serial adapters (in some computers work in other doesn't).
However the other day I saw that Buffalo has a little program to find their NAS boxes (or network drives) when you don't know their IP address or got the wrong one so I assume they do it by looking for mac addresses.Is there any way of doing this with VB 2005 or higher? Basically I don't know the IP of the embedded server so I need to find it on a network, how do I find it?
a) I could do a general IP scan assuming it is on the same subnet than the host computer
b) if it has a different subnet... a general IP scan is not going to work, is it?
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Jul 29, 2008
At my workplace I have been developing a server/client application which receives on port 8000 and sends on 8001. We do not have any other applications that use these ports, but we do have an application that accesses an SQL database in which part data is stored.
When I am doing testing on the application, if the server were to crash while the client app was sending a packet, could this lost packet cause issues with the network at all?I ask because for some reason we have been receiving connection timeout errors from the application that stores our product data, but we haven't made any changes or started running any new jobs on the network that I am aware of.
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Oct 29, 2009
I'm trying to figure out, how I could access a webcam on another computer withing our network. It could be P2P as well.
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Dec 16, 2008
i am using serial communication to read from a plc.The plc will send a string :&H3A as a header byte then C(which is a variable that contains data)I want to read and mask out the header byte.I use the following code but cannot read anything.
Private Sub btnread_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnread.Click
Msg = SerialPort1.ReadExisting
count = Val(Mid(Msg, 1, 2))
Lblno.Text = count
[Code]...
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Oct 28, 2004
I am writing an application to grab attachments from messages in a particular folder in an Exchange server account and then process them. The processing of the attachments should be no problem, but what I don't know how to do is to connect to the Exchange server and access the messages.
What I would like to know is what references and imports I need, and how to access the various objects in the object model. I have been looking at CDO already, but I have had problems finding help on the Internet that is relevant to VB.NET.
For example, I'd like to know how to create the Exchange object, log in and navigate to the folder that has the relevant messages in it.
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Dec 18, 2011
I'm looping through items in a listview. For each item, it deletes a file containing information stored and re-writes it with new information from the listview item.
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Mar 16, 2009
I would like to search event logs on my network for a certain EventID. I havent worked with Event Logs before and was wondering how difficult this task would be.
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Aug 1, 2011
how you can allow vb.net to access a file/folder within a domain group and retrieves it permission setting to determine if the user have access or denied access to a certain folder?
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Dec 27, 2008
I am trying to build an IM program i found one (see attachment) but it is network only and i want to build one that goes over the internet?
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Apr 26, 2009
I put it in Communications.For My programming class at school we are required to have made a program. So I decided to make a LAN messaging program which uses VB and Microsoft Winsock Control 6.0. Im quite new and noob at using VB so i'm using a tut here, url... to make the base program.As you can see if you've read it, he uses Microsoft Visual Basic 6.0, while I use Microsoft Visual Basic 2008 Express Edition.
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Aug 18, 2009
Here is my idea so far: I have a bunch of computers connected in a local network. One of them is a MySQL server, one will have a vb.NET program wich will act as a "second server" and the rest will be different clients. What I want to do is that the "second server" will send out some kind of message or network package to some of the clients in the network, and they will execute a code based on what message it is, or what kind of package it is. I'll give you a simple example:
[Code]...
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Dec 17, 2008
I dont know wether this is the right place but would i be able to use somthing like streamreader to change a .txt on another computer? If so, how?
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Jul 11, 2010
I want to develop Modbus RTU Master program ..I am expert in Modbus communication and I have designed the Modbus pre-programmed remote controls ,, Now I want to interface some Modbus RTU slave devices to my own developed application ... and looking for kind guidance ..I am much familiar with the Modbus RTU syntax and I've tried following to initiate the the master query but I am getting initial 3 bytes ok ,, rest of them are changing the values on COM port so slave is not responding to my command ..
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Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
Dim BYTE1 As Byte = 1
Dim BYTE2 As Byte = 6
[code].....
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Aug 5, 2009
Lately, ive been using winsock quite a lot. I made a chat application, and now i want to make a remote desktop program. I dont want a half asses one, where u can press buttons that send info to the server, but i want to have a client server relationship where you see the screen, have control to the keyboard, and the mouse. Any tips on how i can go about this?
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Dec 6, 2008
I am writing a program which sends email automatically. Sending the mail works fine. The problem is that this will be on portable systems and not always have internet connection.
Is there a way to determine if an internet connection is available before attempting to send.
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Jun 19, 2008
I'm trying to write a vb.net program that will upload a file to a FTP site that has SSL (explicit, although I'm not sure what this means).The sample code and explanations I've Googled always assume when it's SSL that I'm using a client certificate. But I have no certificate to load.I simply need to login, accept their certificate and upload my file.When I accept their certificate am I actually installing it on the client? For example of FileZilla a box pops up and I just click on accept, then my login is complete.
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Oct 31, 2008
I want to create a program that will keep track of the amount of (network/internet download) data that has been received, but I have know idea how to go about doing it.Where would be a good place to start with this type of development? Or could some one give me example code that will get me started.
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Aug 27, 2008
Like the title says, is there a freeware program out there for serial communication that is better than Windows Hyperterminal?
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Jan 26, 2009
I am using VB2008 Express and am curious how to send a command via RS232 communications. The string that I need to send is 02h PON 03h. The start and end bits are 02h and 03h.
How can I convert 02h and 03h to its ascii form. In hyperterminal, I use the sequence {(hold)ALT 0 0 2} on the number pad to send the start bit.
I am using this code currently without the start and end bits
Code:
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Apr 26, 2012
I have developed some programs for processing and issue-coding electronic documents. I am teaching myself how to work with SQL Server because I want these programs to work with electronic documents imported into SQL Server as opposed to messing around in a folder stuck on the desktop, for example. From there I want to expand on the program so that it is a network enabled program.
[Code]...
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Apr 9, 2010
I have my program that runs from a workstation and the SQL DB is on the SERVER.I am having a lot of problem with it as the VB.NET program wont refresh the dataset.I would like to test the same by putting the SQL DB on a network drive, and run the program from another workstation.Just to narrow down the problem.My Question is this. I install the SQL DB on machine A and then install my program on Machine B?
What should I do to get Machine B to access the SQL DB on Machine A.Will sharing the SQL FOLDER be good enough for my program to access the DB of course, I have to modify the connection string on my program, but other that is there anything more to be done.
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Jan 17, 2009
I have a simple chat program i have made, it works but with a few errors.
1st if it can't find the physical pc it is trying to connect to it crashes.
2nd if it finds the physical server but not the program (server) running it says "the computer actively refused the connection on IP/Port" and then crashes.
Code for connect button:
IP = txtboxip.Text
Port = txtboxport.Text
[CODE].....................
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Oct 16, 2009
My Vb Dot Net Program Can Not Run From Network. When i try to register my program to GAC,it said my assembly dont have strong key,
i cannot put strong key, because i put component vb6 to my program..
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Sep 8, 2009
I have written small a software. I want to install it on a server and and make it accessible for all the other users on network.
How can I retrieve the server name (the computer program installed) with .NET?
Also, sharing the "Program Files" folder doesn't look like a smart idea for making the program accessible from the other computers.
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Feb 7, 2010
I make my Program to Connect via Network to Database..[code]
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Nov 1, 2009
how to allow dot net program to run from network without strong key ? since i have program put on network, ussually i put strong key on that assembly, and it can work and run from network this program.. but there is some component com object that make me to cannot compile if i put my stong key, so i compile it without stong key, but it came i cannot run this program from my network..
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Sep 29, 2009
How to handle the Network failure error message,and how to simulate it?
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