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It's possible that isnce you have two read/writers talking to the same stream they are corrupting the data. You should either use separate streams or lock against a resource (see the lock keyword for C# or the System.Threading namespace members). Even reading the stream advances the cursor so that if both read the stream at the same time, they get fragmented data. Writing would obviously be a problem if you didn't synchronize access to the stream.
If you look, there's also a ReaderWriterLock class in System.Threading that may be helpful as well, but you must still be mindful of the cursor being repositioned with each read and write to the same stream, even by different callers.
Microsoft MVP, Visual C#
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Look..
The Server haves a while loop, in this while loop we got a switch case, Before the switch we got the Dezerialize cod(one row) that Deserialize the stream object to a command object. After this the switch redirect the thread to right case, if it is where we waite on the object that the commad obj was telling us is on the way. It my be a update object or what ever.
When this is done it goes right up to Dezerialize row again there is waits on the next command that arrive.
The Client have something like the Servers loop.
This stream is also used to send obj by other controls in the client and server.
So Far:
We have loggd on to the server with somw clients, the clients can talk and act like thay shold.
When two clients is making a table to play the game on the head form is disposed, but the stream(TcpClient) is sent to the new game form, where we start a thread and goes in to a new loop, a game loop. So far, nor problems.
But now when we have playd we will start up the main form again, and this we have disposed so we start up a brand new and sends over the stream(TcpClient) from the game form and then dispos the game form.
Now we are back in main form. But when we goes in to the while loop that reads the stream for command obj we get an error, and it is this error we are trying to solve.
When we get in to the loop and the Dizerialize(stream) is used, it gives us an exception like: No instance.
But if we use a break point and step we could se that the stream is set to Read = tru, Write = true, and that the data(Long) is containing data that is to big , also there is some error on the position of the stream obj.
we have tryed to read this thing that is in the stream by casting it to simple object and then take a look in the objects type. But we get the error when it is trying to dezirilize it.
We thougt that if there is somthing in the stream buffert that is maby a bit of an old object or somthing we have to get this flushed, so we tested to use Flushed on the stream but the stream is steal containgn error like before.
How could we do ? we have thought of closing the connection and open a new stream, but we have to maintain the connection with the server at al time, otherwize the server will consider the client offline.
And if we got it right, we can not throw the stream and creat a new stream by TcpClient.getstream we will lose the connection with the Server int this case.
Best Regards
Jimmy
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If the position is incorrect, you could reposition the cursor using Stream.Seek (if Stream.CanSeek is true). Based on your comments, however, it's hard to determine exactly what is going on. This would require debugging the app, which you're already doing.
Microsoft MVP, Visual C#
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I understand.
we have checkt that the server is not sending any information, so we think that there are som fragments left in the stream.
The only thing that we whant is to clear this buffert and move on, is ther no way to do this? do we realy have to close connection and reopen it?
Reagards
Jimmy
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Normally you could call Stream.SetLength, but the NetworkStream (and casting it won't change the stream Type) always throw a NotSupportedException.
Thinking there'd be fragments doesn't make sense, however. The stream is streamed between the client and server. When you read or write, it always starts with the current cursor location and advanced the amount that you read or write. Everything else is "forgotten".
What you should try is writing a client that will simply buffer what the server sends and writes the content to a log file, as well as makes it available for your application. This wouldn't be a bad idea to leave in the product, either. By "throwing on a switch" (as some applications - including games - have) you could debug communication with the server.
Microsoft MVP, Visual C#
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Yes I have lookt at the Stream.SetLength but as you says it will thow a NotSupportedExcepton.
Okay thats good that you explained how the stream workt, we thought that it hade som kinde of buffert that it stores the incoming data in and then work it when it reads the stream.
We have thought of making a sort of log in the Server so that we could see exacly what the server sends and recives from who.
We have alot of timepresser here right now, but i think that this solution(ologg) will solve our problem fastern then fuling around with the flush and things.
Alot of thanks =)
Ragards
Jimmy
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Hi to all,
I want to ask: I wrote a Visual C# application using VS.NET 2003, so it was created to run under Framework v 1.1 and when I try to launch my application on the mashine where VS.NET 2002 installed I just can do it and some exception occurs. The question is how can I create an assembly wich able to launch on Framework 1.0 using VS.NET 2003?
developers team
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VS.NET 2K3 will only build for the .NET Framework 1.1. You could install the .NET Framework 1.1 on the target machine and your app will run without problem.
Now, you could also go into the project properties of your app, Common Properties, General and click on Supported Runtimes. Here you will be able to select which version of the Framework your app will compile against, v1.0, v1.1, or BOTH. But, there's a catch...since v1.0 of the .NET Framework doesn't support certain features v1.1 does and v1.1 has some implementation changes from v1.0, your app might not compile against v1.0 or it will compile, but run differently depending on which framework it's running on.
RageInTheMachine9532
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Thanx. Tommorow I'll try to intall my homework  and I hope you solution will help...
www.xedom.com
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Just wanted to add that if you built for 1.0 and ran against a newer framework, you don't need the .config. The framework used is the same or newer than what's referenced in the assembly. The same "gotcha" that Dave mentioned still applies, though, except that deprecated functionality (stuff that doesn't exist in newer frameworks) will cause exceptions to be thrown if you use them, if your assembly even runs. This is much more uncommon, though, as most functionality is usually left in without being changed (functionality may be added to existing classes, but this still works).
Microsoft MVP, Visual C#
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Anyone knows how to preview a custom file format with a bitmap in windows explorer?
For example, the 3D Studio file format (file.3ds) is not a gif or bmp or anything. However, if you select it windows explorer, an image preview of the file pops up on the left anyway just as if it were an image file. How is this done?
- Peder -
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This is done via the IExtractImage shell interface. You can find more information about the interface here[^].
If you want to leverage this functionality in your .NET application, see Thumbnail Extraction Using the Shell[^] (something I found quick by googling).
If you have created a document format in .NET and want to support this interface, you must declare this interface in your code like this:
[Guid("BB2E617C-0920-11d1-9A0B-00C04FC2D6C1")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IExtractImage
{
void GetLocation(
[MarshalAs(UnmanagedType.LPTStr), Out] string path,
[MarshalAs(UnmanagedType.U4), In] int pathSize,
[MarshalAs(UnmanagedType.U4), In, Out] ref int priority,
[In] ref Size size,
[MarshalAs(UnmanagedType.U4), In] int RecClrDepth,
[MarshalAs(UnmanagedType.U4), In, Out] ref int flags);
void Extract(IntPtr hBitmap);
}You implement this interface on a class that also exposes a CLSID (Class ID - use the GuidAttribute to explicitly define a CLSID using uuidgen.exe or something). You then register this using regasm.exe from the .NET Framework. The usual regsvr32.exe will not work since an assembly does not export the necessary functions (like DllRegisterServer).
See Nick's article, Creating a CCW for COM-Enabled, non-.NET Applications[^], for more information on exposing .NET classes as COM components.
You would also have to manually register this CLSID under the PersistentHandler registery key under your extension's registry key. This is how the shell determines if your extension supports thumbnails and determines how to load them (using the CLSID of your class). More information about this is available in the Platform SDK. You can make this easier by attributing a couple static methods with the ComRegisterFunctionAttribute and ComUnregisterFunctionATtribute, which executes code (like your registry code) in addition to the standard stuff that regasm.exe does when it's executed with your assembly as it's command-line parameter.
Microsoft MVP, Visual C#
My Articles
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This was very informative and interesting! However, I believe I might have expressed myself a tad unprecise. My question was rather how to enable the preview mode on a file type I create myself.
And then, secondly, I suppose the continuation will be to get hold of some image, remove the file headers, and finally embed the image data at some address in the file. Maybe the trick is to make my own derived file class?
- Peder -
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Yes, and what I said is correct. You must define a persistence handler for your document type and register it. Windows Explorer will use this information to generate a thumbnail. The links I gave you provide you with more information about this process.
How your IExtractImage implementation gets the image is entirely up to you. For many Microsoft Office types, a thumbnail is generated when the document is saved and stored in the compound document structure. The persistence handler for those document types extracts that image.
For support videos in Windows Explorer, the IExtractImage implementation extacts the frame so many seconds into the movie and uses that for the thumbmail, which is cached in the Thumbs.db.
Read the Platform SDK for more information. You can also read Mike Dunn's The Complete Idiot's Guide to Writing Shell Extensions - Part I[^], a step-by-step tutorial on writing shell extensions in C++. There is a whole series. This doesn't cover the IExtractImage extension, but should give you a basic idea of what I already covered.
I also gave you the information you need to know how to implement the shell interface in C# and register your .NET assembly as a CCW, or COM-Callable Wrapper, so that it can be used by the shell to use your IExtractImage implementation for your document type.
Microsoft MVP, Visual C#
My Articles
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I've been doing some research for a migration and am having a hard time determining whether it is possible/feasible to call javascript events from a windows form control that's embedded in a web page.
Essentially I'm wanting to use the controls in an activex/applet situation and I want to call a javascript function from the compiled C# control. I would think I could put an event on my control and have the java script 'subscribe' to that event and then I could just fire it as appropriate from within the control. However I'm having a hard time finding a way to do the subscription.
I'd like something like this:
C#:
public class Control1 : UserControl
{
public delegate void SomethingDelegate();
public event SomethingDelegate OnSomethingHappened = null;
..
.. fire the event in the script at some point:
OnSomethingHappened();
..
..
}
Javascript:
<object id="tabControl" name="tabControl" classid="GUIControls.dll#GUIControls.TabControl" width="445" height="250" onsomethinghappened="doSomething" viewastext="">
function doSomething()
{
alert("handled event in javascript");
}
Anybody tried this before? Any help appreciated!
Tim
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Yes, it is possible. You must use automation interfaces in your contro, however, so that scripting engines can access them. See my old article at DevHood, User Controls for Winodws and the Web[^].
Keep in mind that you must follow COM guidelines, and writing for COM dictates that you should use good practices in .NET as well, such as never changing a published interface (instead, derive a new one and call it IMyInterface2 or something allow those lines), and NEVER use auto-generated class interfaces. Microsoft does this in their samples, but if you read deeper (or have any experience in COM and COM interop with .NET), you'll see they tell you not too (nice, huh?). Because you can change the relative locations of properties and methods in .NET without affecting functionality, this is fine. But it screws-up auto-generated interfaces since methods and properties will be in a different VTBL order, and possibly will have different DISPIDs (if you don't explicitly set them with the DispIdAttribute). My article covers this a little as well.
You can expose methods, properties, and even events this way. Just give your OBJECT tag an ID and you can script it. You can hook-up event handlers using attributes or through scripting. My article covers this as well.
For a little more information on following COM guidelines in .NET (since that wasn't really the focus of my article), see Nick's article, Creating a CCW for COM-Enabled, non-.NET Applications[^]. Nick even added what I mentioned above into his article, you might notice. 
Microsoft MVP, Visual C#
My Articles
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Wow, awesome article. Really hits home on what I'm looking at. The link you had to the full source is broken however
Do you still have a copy?
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No I don't. The article is very old and the site was down for quite some time. I guess they didn't get everything fixed properly (like I noticed my image was missing as well). There should be enough information in the article, however. Just read about the classes I use for more information in the .NET Framework SDK documentation.
Microsoft MVP, Visual C#
My Articles
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Hey, I got it working. I've got to research the security on it a little more but it seems like it might be an option for me.
thanks a lot Heath!
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You should read Understanding .NET Code Access Security[^], as well as follow his links to resources on MSDN.
One big mistake is that some developers expect to have FullTrust permissions. This should not be. Determine which permissions your control absolutely requires and use the SecurityPermissionAttribute with the SecurityAction.RequestMinimum (along with what you require) in your assembly attributes (so prefix it with "assembly:"). Then use either declaritive or imperitive security demands throughout your application to make sure you have those permissions.
As far as deploying the necessary code group, either post an XML fragment with instructions for user to import it, or write a class that derives from Installer and use that in a Windows Installer package in VS.NET as a custom action. See How to configure .NET Framework security settings and how to deploy a .NET Framework application[^] and read the related links at the bottom for more information and alternatives (like creating and removing the code group using the caspol.exe utility).
Microsoft MVP, Visual C#
My Articles
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Sounds good.
Since my application is primarily for intranet use, I'm thinking I could just install dotnetfx.exe on each machine and then call caspol appropriately to set the intranet zone CAS security. Of course these steps would be in one deployment package. I still have to determine how much 'trust' to give the intranet zone.
One thing that is still confusing me is that even if I strong name the controls and set up a code group in CAS for that SN and give the code group a bloated permission set, unless I set the zone security, the control still won't load. It's like the zone security is overriding the code group.
Or maybe the control code is winding up in another code group that correlates to the zones..
I'm a bit leery of giving the intranet zone an elevated trust level and wish I could just elevate trust for my application's assemblies. Any thoughts on this?
Tim
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Don't elevate the Intranet_Zone code gorup. Instead, create a new code group using the Url to your assembly, or the strong name (and assemblies should always be strongly named - there's just no excuse for not strongly naming them and it gives you many more benefits than not). Other assembly evidence doesn't work (at least in 1.0 - I reported this to Microsoft a long time ago back in the 1.0 beta days - or perhaps early after it was released), and the Site evidence doesn't always work correctly, although I haven't been able to determine why.
IEExec.exe only gathers site evidence (evidence about the site where the assembly is hosted) and strong name evidence.
I've sent you a class from the installer we use in the Windows Installer package.
Microsoft MVP, Visual C#
My Articles
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The URL evidence is working, I still can't get it to work with the strong name.
I've set up two code groups at the enterprise level. One based on URL evidence and one on a strong name key. The control is signed with the strong name.
For some reason, the control is only showing up as meeting the URL evidence. I'm testing it by hitting 'evaluate assembly' in the .NET security tool, runtime security policy tree node and typing in the url to my assembly.
I can't really understand why it's not thinking the assembly is meeting the strong name evidence. It does think it meets the strong name evidence if I select the assembly a different way in the tool, i.e. by browsing to the .dll.
Hmm....
Well the URL evidence will work for me. It'll just make my rollout more of a pain.. because of our deployment methodology (we don't host software -- so I would have to let sysadmin type people specify these URLs somewhere in configuration - yuck).. :/
Have you noticed weirdness with the strong name evidence when doing these controls? Even if I specify levelfinal for the codegroup, it still doesn't recognize it.
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Strong name should work, but there's nothing wrong with URL evidence.
One way that I roll-out code groups (though I typically use the Machine policy) is to write an installer class like I mentioned, wrap that as acustom action in an MSI package, and add that to our domain's group policy so that it installs on machines that the GP covers. When written correctly, this makes it easy to roll-out your code group. This procedure is also recommended by Microsoft. Of course, this would only work if the .NET Framework was installed, but that's a given. You could always have the install detect if it's there and install regardless, or include that dependency on the .NET Framework as a Launch condition. The user would not be presented with an error in either case.
Microsoft MVP, Visual C#
My Articles
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Excellent advice. Thanks a lot.
I have one other small thing that I'm wondering whether you've come across since you seem to have done this type deployment before.
In a test control I'm playing with now as part of a prototype, I try to open up a tcp connection to my app server using the tcpclient class from the FCL. I have done tons of tcp so this should be trivial for me ( :> ). Anyway, when I run my control in a windows form the tcp request behaves like I expect i.e. I see the syn - syn ack - ack - and then my push and receive from the server.
However, when I run the control when embedded in a web page (it's got full trust and full socket access in the CAS policy), I get the syn - syn ack - syn, but then for some reason a request is being made to the server on port 445 which is the Microsoft directory service port. My push (my request) is then waiting like 2 minutes for something to come back on port 445 before my request goes through. I can see all this in ethereal but have no idea why the control or the framework is running a request to port 445.
Have you come across this?
Tim
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