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Can we send a Form type object from a Remote Server.
If yes then how.
Actully I have tried it but I could not succeed.
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System.Windows.Forms.Form inherits indirectly from System.MarshalByRefObject, so there is no reason why it can't be remoted - in fact, I just knocked up a test server/client then and succeeded.
However, as leppie said, you can't pass a window handle across remoting boundaries - they mean nothing on two different systems.
You'll have to expose the object (probably as a client-activated type), but there is a snag: you cannot pass your form as the parameter to Application.Run().
This is because Application.Run(Form) will actually create a new ApplicationContext based around your form and then attempt to attach a delegate to your form's HandleDestroyed event so that it knows when to terminate the message loop. The problem is that ApplicationContext is not remotable (i.e., not derived from MarshalByRefObject nor is it marked as Serializable), so you can't pass the target method information in the delegate across the remoting boundary. This will result in a SerializationException.
Instead, use Form.ShowDialog(). That will work.
Good luck.
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Actually, I'm going to have to eat my words here.
Read This.
My tests were succesful - when the remote server and client were run on the same machine. Not only that, what happened was that the form was not displayed in the client process, it was displayed in the server process! Totally useless.
If you run the server on a seperate machine on your network and attempt to connect with the client, you'll end up with a RemotingExcption, telling you that permission was denied to create the instance of the form. I'm not sure why this occurs.
Hmm. Oops. Oh well, all part of the learning experience 
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Hi all,
I am design a three layer system in C# (view layer, business object layer
and data layer). But when I look into the J2EE infrastructure, the object
bean(business object) incorporates the SQL data function into the object itself. It seems violates the layer design principles coz it mixes the data layer with the business object layer. But in the other hand, it seems a more OO design coz the business object integrates all those related information into the business object, so when there is a later change in the business object specificiation, the developer needs to change only the business object instead of changing the object and the data layer.
So what approach should I choose ?
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I think the whole decoupling of the data-layer from the business-layer is overrated.
The main benefit touted is being able to switch to different data providers. But how many apps and users ever do this? If you need to do this, and I mean really need to, then your course is already chosen.
If not then go with the easier and more efficient second option you mention.
regards,
Paul Watson
South Africa
The Code Project
South-East Asia Disaster: How you can help
Pope Pius II said
"The only prescription is more cowbell. "
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Hi,
I did a program and in that part i have given a loop. This is a program which reads any xml schema file and according to their datatypes , It creates 200 values in a xml file. Each values should differ from the other. I have done it for other datatypes. But for DateTime, I dont know how to change the data, Pls have a look through and sent me. Its very urgent for me now. I ma sending the loop part alone and I will mark my dobtful part alone in bold . just give an idea how to do.
private void button2_Click(object sender, System.EventArgs e)
{
dataSet1.ReadXmlSchema(txtSchema.Text);
foreach (DataTable dTbl in dataSet1.Tables)
{
for(int j = 0; j <= 200; j++)
{
object[] oValues = new object[dTbl.Columns.Count];
int i = 0 ;
foreach (DataColumn dColmn in dTbl.Columns)
{
switch(dColmn.DataType.ToString())
{
case "System.String":
oValues[i] = (string) "This is string" + j;
break;
case "System.DateTime":
oValues[i] = new DateTime(2004,10,12) ;
break;
}
i = i+1;
}
dTbl.Rows.Add(oValues);
}
}
}
santhosh
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Are you asking how to increment a DateTime? If so then use oValues[i] = new DateTime(2004,10,12).AddDays(j); in your code. That will add a number of days equal to j onto your base date of 2004,10,12. You can also add minutes, seconds, hours, months, weeks or years using the various methods of the DateTime class.
regards,
Paul Watson
South Africa
The Code Project
South-East Asia Disaster: How you can help
Pope Pius II said
"The only prescription is more cowbell. "
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Thanx paul. I got the result. Your information helped me out to get the result.
John santhosh
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Does anybody know the code for opening a browser window from C# windows code. I had tried to use the System.IO.File construction without success. The file may in fact open if I open a .htm file alongside the windows application, but it does not open the browser window.
I would need to know how to open a browser window from a menu item, and second how to open an .htm file that would download a file from a remote internet web server, that would place the file in a specific directory. Any suggestions for a different way to approach this dilemma? I know that it is possible, because I have seen some applications do it.  
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The easiest way is to use Diagnostic.Process and the Start method as explained in this CP artile; Using Diagnostics.Process to start an external application.
If you pass in a full URL then Windows will know which app to open e.g. Internet Explorer or FireFox or whatever the default URL handler is.
As for your second question you could pass the URL of the file to download and Windows will handle it in the usual manner when downloading files from the net. i.e. It will open a Save As/Open dialog.
regards,
Paul Watson
South Africa
The Code Project
South-East Asia Disaster: How you can help
Pope Pius II said
"The only prescription is more cowbell. "
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Paul Watson:
Thanks, I appreciate the input. However, is it possible to download the file from the net "without" opening the save as dialog box, and to simply place the file into the required directory for further processing? And if so, should a timer be activated to make certain that the file has been completely downloaded?
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If you are running an app on the users machine then sure, you can download a file and put it on the users machine. You can run it too once it is down.
You can use the WebRequest class to get files over HTTP. You can then use a stream writer to write it to disk.
regards,
Paul Watson
South Africa
The Code Project
South-East Asia Disaster: How you can help
Pope Pius II said
"The only prescription is more cowbell. "
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I was wondering how can I have my application setup and recieve global shortcuts. Basically, I want my program to run in the background and recieve the shortcut no matter what application has focus (kind of like WinAmp does).
Where can I find articles/example code on this? Or where should I start to look in the SDK?
Thanks for all your help!!
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I believe you'll have to use some Windows Hooks for this. I read an article on it once, I just have to find it again...
Here it is:
http://msdn.microsoft.com/msdnmag/issues/02/10/CuttingEdge/
Here's a good one about global hooks from CP.
There are two types of windows hooks: local hooks, which catch messages coming in for one particular thread, and global hooks, which catch messages for all threads on the entire system.
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Thanks alot for the info!
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 I have a main thread that executes many threads of a specified class. All are the same class.
After creating the threads and executing then at the same time, I need a way in which I can monitor all the threads.
If one of the threads meets a certain condition I need to be able to contact each thead that was started and call the join method on it.
Its model is like so:
Controller A starts
Creates x number of threads with class A
one of the class's (A) will signal its finished and at that point the controller will call join on every thread started.
I need a way so make sure all threads created are shut down cleanly.
Any Ideas,
Nick
I'm not an expert yet, but I play one at work. Yeah and here too.
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I'm definitely no expert, but here's my idea:
Class A should expose a ManualResetEvent via a public property. When the class is constructed, create an instance of the ManualResetEvent class and set it's initial state to non-signalled (by passing in false as a parameter to the constructor).
Now every object you create of class A has it's own ManualResetEvent, which can be used to signal when that class has completed it's work by calling ManualResetEvent.Set().
When you create an object of class A, store it's ManualResetEvent in an array of type WaitHandle. This could be the tricky part - if you create the object before the thread starts, you should have no problems. However, if the thread creates the object, this method will not work (as you can't get a hold of the object).
The controller will then create all of your threads and keep them in a collection for access later so that you can call Join on them.
Now, perform any processing you need to do for the Controller and when you're ready to wait for your signal from one of the classes, simply call WaitHandle.WaitAny(WaitHandle[]), and pass in your collection of WaitHandles as the parameter.
WaitHandle.WaitAny() will immediately return when any of the WaitHandles becomes signalled. Once this occurs, loop through your collection of threads and call Thread.Join() on each of them.
I hope that makes sense. It may not be the best way to do it, but that's what I would do personally (like I said, I'm not expert  ).
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reply ?
Its a very good idea.
So would I have class A inherit the Thread class and how would I implement the WaitHandle?
How does the wait handle get back to the thread to Join the main thread?
I have it woring, but a little confused on useing WaitHandles which I really want to do.
Thanks,
Nick
I'm not an expert yet, but I play one at work. Yeah and here too.
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Hi Nick.
First I suggest you read the documentation on the System.Threading.ManualResetEvent class (here). In a nutshell:
The ManualResetEvent provides a way for you to notify other threads when you have completed a task.
All Class A needs to do is provide it's own ManualResetEvent that the controller can access and store away. Once all of the threads are created the controller can then call System.Threading.WaitHandle.WaitAny(), passing in an array of the ManualResetEvents (one per class object you created) that it kept. As ManualResetEvent derives from WaitHandle, this is perfectly valid.
The call to WaitHandle.WaitAny() will then block the controlling thread until one of the ManualResetEvents you supplied is set to signalled (ie, indicating that a class on another thread finished processing - you don't know which one, but you know that at least one of them has finished).
Once this occurs, the controller thread will then be allowed to continue, regardless of whether the other threads have finished processing or not (that is possible because you called WaitAny, not WaitAll).
Now, you asked how the WaitHandle notifies the other threads that it has been signalled. That one I don't know, sorry. I might do some research into it, however.
If you need any more help, let me know.
Good luck.
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Greatings !!! I have a simple (I think) problem.
I need a thread that executes some part of a code and
during that time i want to suspent or pause the main application thread.
This way the application do not appear (Not Responding) or is the same? Do you have another solution?
How can i do this?
Sorry for my English !!!
thanks.
Bruno Conde.
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Arg, please don't abuse threading like this. 
If you want to execute something in another thread yet suspend the main thread why bother seperating the two things into two threads?? You are not gaining anything using threading like this. Just do all of the work in the single main thread.
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In most cases I would totally agree with you.
There are cases, however, when you may want to execute something in another thread and eventually have your application block until it's finished. This is quite possible with the asynchronous pattern, when you first call Begin*, do something else, then block on End*. I would add, however, that's more common to use an AsyncCallback so that you don't have to block, but you could.
An example might be downloading a file via HttpWebRequest.BeginGetResponse. You could update the UI and then call HttpWebREquest.EndGetResponse to block until the HttpWebResponse is returned.
I'm not disagreeing that - if the original poster needs no functionality like what I descrbied - it is an abuse of threads. There may be a purpose, however (of which we would know since the original post mentioned nothing of this sort).
This posting is provided "AS IS" with no warranties, and confers no rights.
Software Design Engineer
Developer Division Sustained Engineering
Microsoft
[My Articles] [My Blog]
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Agreed, there are cases where you really need to use multi-threaded behavior and the example is a perfect example (begin/end process pipelines are classic MT fodder). Without more information however it sounds like the described problem can be fixed simply by avoiding MT all together.
Sometimes the vague nature of the questions makes me suspicious which is why I asked the question. If they can come up with the answer on why their app relies on MT behavior that requires going against MT behavior then we can actually go forward and get a better solution than vaguely throwing code around.
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