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Hi!
I'm writing a wrapper assembly for an interop assembly that's not very nicely implemented. The interop is wrapping a COM object that was primarily meant to work with VBScript, and many methods return untyped values, although they could indeed return them typed.
Almost all classes in the assembly have the following structure
<br />
<br />
internal interface IBaseObject<br />
{<br />
object baseobject{get;}<br />
}<br />
<br />
public class WrappedSomething : IBaseObject<br />
{<br />
private InteropSomething _baseobject; <br />
public WrappedSomething(InteropSomething baseObject)<br />
{<br />
_baseobject=baseObject;<br />
}<br />
public object baseobject<br />
{<br />
get{return _baseobject;}<br />
}<br />
}<br />
The IBaseObjct interface is there to make it easy to pass these wrapped objects around inside the assembly, and give easy access to the wrapped object.
Of course this works just fine, but I don't like the fact that the classes exposes the property baseobject publicly. I don't want to give other assemblies access to the wrapped object. At least not as easily as it becomes when the property is public.
I could of course solve it by inheriting an internal class, but quite a few of the classes benifits greatly from inheriting other common (publi) functionality from other classes, and since there is no multiple inheritance....
Any suggestions?
Wouldn't is be viable to have the option to implement internal interfaces' methods internal only?
<br />
internal interface ISomething<br />
{<br />
int DoInternalStuff();<br />
}<br />
<br />
public class Dog : ISomething<br />
{<br />
internal int DoInternalStuff()<br />
{<br />
}<br />
}<br />
Since the interface is internal, I can't see any problem with declaring the implementing methods internal as well.
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Thanks, I thought I had tried that, but obviously I hadn't..
However, it's not quite there yet.
If i use
<br />
object IBaseObject.baseobject<br />
{<br />
get{return _baseobject;}<br />
}<br />
I can't access baseobject directly. E.g
<br />
public void DoStuff(Dog Victim)<br />
{<br />
DoInteropStuff(Victim.baseobject);<br />
} <br />
This results in :
'Dog' does not contain a definition for 'baseobject'
Instead I have to write
<br />
public void DoStuff(Dog Victim)<br />
{<br />
DoInteropStuff(((IBaseObject)Victim).baseobject);<br />
} <br />
And, although I'm not sure, it seems that could lead to undesirable boxing/unboxing. Maybe it doesn't. I also find it strange that baseobject now becomes effectively internal, but I can't expose it as being internal.
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emission wrote:
And, although I'm not sure, it seems that could lead to undesirable boxing/unboxing. Maybe it doesn't. I also find it strange that baseobject now becomes effectively internal, but I can't expose it as being internal.
Boxing and unboxing[^] describes the process where value types (eg, structs, primitives, and enumerations) are wrapped in objects or vice versa, basically. Read the link for more details.
Unless Victim is a value type (highly unlikely, especially in COM) there is no risk of boxing or unboxing - only conversion.
If you want to truly limit assembly access to a member or class, then learn to utilize the security infrastructure of .NET: Code Access Security[^].
If you want to limit access to a single assembly, you would attribute your member like so (declaritive security):
[StrongNameIdentityPermission(SecurityAction.Demand, Name="MyAssembly", PublicKey="0123456789abcdef")]
object baseobject
{
get { return _baseobject; }
}Where Name is your assembly name and PublicKey is your hex-encoded, 16-character public key (which you can get for your assembly in many ways). If you do not strong name your assembly than you have no security. The public key token is derived from your private key used to sign the assembly. If you don't sign the assembly and don't keep your private key private then anyone can spoof your permission demand.
If you want to allow all your assemblies access to the member, then just specify the PublicKey field and use the same key to sign all your assemblies (this is typical for a single organization anyway).
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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Thank you for enlightening me on the boxing issue. Now I know what that means.
Is there no overhead when converting, i.e using ((IBaseObject)Dog).baseobject instead of directly accessing a public Dog.baseobject?
Heath Stewart wrote:
If you want to truly limit assembly access to a member or class, then learn to utilize the security infrastructure of .NET: Code Access Security
Yes, I've studied this issue, after reading an article in MSDN Magazine, and this may very well be of interest in some projects. However, this time it's more a design issue than a security issue, and I just curiously wonder about the reasons behind.
I think that it would be logical that with interface
<br />
internal interface IAnimal<br />
{<br />
int Age{get;}<br />
}<br />
...a class like this
<br />
public class Dog : IAnimal<br />
{<br />
internal int IAnimal.Age<br />
{<br />
get {return 1};<br />
}<br />
}<br />
..would be quite enough to satisfy the interface contract. In fact I think it satifies the contract more clearly than
<br />
public class Dog : IAnimal<br />
{<br />
int IAnimal.Age<br />
{<br />
get {return 1};<br />
}<br />
}<br />
...does.
Since I'm obviously wrong I would like to be corrected, so that I can understand the reasoning behind this.
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emission wrote:
Is there no overhead when converting, i.e using ((IBaseObject)Dog).baseobject instead of directly accessing a public Dog.baseobject?
Negligable. A cast is an instruction that must be processed but compared to boxing operations these are trivial.
emission wrote:
However, this time it's more a design issue than a security issue, and I just curiously wonder about the reasons behind.
No one said that CAS has to be used only for security. Even the term "security" is rather loose. If security means that you don't want other developers via their assemblies to "see" or even access the member than CAS is what you want. Even with explicit interface implementations (i.e., what you're currently doing) a coder merely has to cast to the interface. Even if you used the BrowsableAttribute or EditorVisibilityAttribute you're only hiding it. The only way to truly deny access to the member is CAS.
In .NET 2.0 a new attribute - InternalsVisibleToAttribute[^] - allows compilers to compile code that accesses internal members from another assembly.
emission wrote:
internal int IAnimal.Age
That would be a voilation. Besides, when you compile this the member is actually private, much more strict than your internal access modifier. The thing is that your object must be cast to an interface object on which the member is truly called, which must be public. The interface object references your object, however, so your private member is not access directly.
You can learn more about implicit and explicit interfaces at http://msdn.microsoft.com/library/en-us/csspec/html/vclrfcsharpspec_13_4_1.asp[^] (C# Language Specification).
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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Thanks! The Language Specification cleared things up.
The solution I'll use is (now that I realize that I can have both an explicit implementation of the interface and a non-interfaced member.
<br />
object IBaseObject.baseobject<br />
{<br />
get<br />
{<br />
return _baseobject;<br />
}<br />
}<br />
<br />
internal object baseobject<br />
{<br />
get<br />
{<br />
return _baseobject;<br />
}<br />
}<br />
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Debugging has been diabled for the c# web projects. How can i enable debugging?
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It would actually be disabled for ASP.NET projects (when compiled, the source language hardly matters which is the whole point of the Common Language Infrastructure, or CLI).
While this belongs in the ASP.NET forum I'll direct you this time to http://support.microsoft.com/search/default.aspx?catalog=LCID%3D1033&query=debugging+ASP.NET+web+applications[^], which describes many differents reasons that is is disabled and how to re-enable it.
In the future, please direct all ASP.NET-related questions to the ASP.NET forum.
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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Hello,
Does anyone know how to create an MS installer of V. C# application from another V. C# application (when I click on a btton, the MS Installer of the other application is created).
Please Help.
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Why would you have one install create another? Please explain exactly what it is you're trying to do.
If you're question is simply about how to create a Windows Installer package (MSI) using VS.NEt, read Introduction to Windows Installer[^] in the VS.NET product documentation and follow the links in the table of contents.
For more in-depth information as well as how to manually edit the MSI package using Orca (a tool within the MSI SDK), see the MSI SDK documentation online at http://msdn.microsoft.com/library/en-us/msi/setup/windows_installer_start_page.asp[^].
Note that the installer projects in VS.NET are very limited.
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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Debugging for my c# projects has been diabled. How can I enable the projects for debugging?
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1. In VS.NET, open the Build menu, select Configuration Manager, then change the Configuration column value for your project to Debug.
2. Find and then completely read a good tutorial on using VS.NET. 
Here's a good start:
http://www.learnvisualstudio.com
John Hebert
Solvitur Ambulando
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Hello boarders,
How to list a files in a particular directory at the client side?
I need to give a user interface to access the files of a particular folder by using windows user control in a web page.
Any help would be highly appreciated
Thanks,
Sreenath
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It's really a matter of permissions. Code Access Security grants assemblies based on their evidence a certain set of permissions or unlimited access. You need to make sure that users grant such permissions to your assemblies using certain host-based evidence (assembly evidence besides strong-name identities are not supported for Internet-deployed assemblies), which you can do using a Windows Installer package to execute an Installer class derivative you would define to create a code group, or give them a batch file to run caspol.exe (depending on your confidence in the users' abilities).
For more about this and about scripting controls (in order to easily provide feedback in the web page itself) see an old article of mine at http://www.devhood.com/Tutorials/tutorial_details.aspx?tutorial_id=388[^].
If you have any questions about that article continue them on this thread since I haven't used that site - and don't plan to - in many years.
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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Stewart,
I got the solution. Thanks for your valuable input. I appreciate it.
I recreated windows control library and added URL as an evidence with permission such as FileIO and Assembly execution. It is working perfectly.
Now I need to give msi file to the client. This msi file should create a code group and permission set. Any idea of how to use the installer package? with the installation it should have created necessary code groups and permission sets.
Sreenath
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I have created a windows control library which contains several form controls. This libaray is being registered on the web page using <object> tag
Eg.,
<OBJECT id=HelloWorldControl1 classid="http://localhost/NBCCtrlLib/NBCControlLib.dll#devhood.rtfcontrol" VIEWASTEXT width=500 height=500></OBJECT>
When client access the web page I have created I should be able to access/read the client hard disk.
Let me know,
Any ideas would def help me.
Thanks,
Sreenath
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Based on host evidence and strong name identity evidence the assembly must be granted permissions to run. In .NET 1.0 the Internet zone was granted no permissions, and in 1.1 was granted very few permissions.
Read Understanding .NET Code Access Security[^] for information about CAS and how to adjust your permissions.
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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Could anyone provide me with a simple C#'s client/server application. I am into socket programming with TCP/IP as my protocol.. Thanks in advance.
----------------------
Seeing the infinite...
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Have you tried searching CodeProject?
http://www.codeproject.com/info/search.asp?cats=3&cats=4&cats=5&searchkw=socket+client+server&author=&sd=11%2F15%2F1999&ed=1%2F17%2F2005
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Thanks Robert!!!
----------------------
Seeing the infinite...
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Hi,
Does anyone know how to get the total commit charge of a system using c#?
Thanks
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Can you describe what you mean by "commit charge"? That's rather ambiquous.
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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I meant, the total memory that is being used by the system (Virtual and Physical).
As is shown by Task Manager.
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