Canonicalization

What is Canonicalization?

Canonicalization is the process by which various equivalent forms of a name can be resolved to a single standard name, or the "canonical" name. For example, on a specific computer, the names c:\dir\test.dat, test.dat, and ..\..\test.dat might all refer to the same file. Canonicalization is the process by which such names are mapped to a name that is similar to c:\dir\test.dat.

When a URL is received by a Web server, the server maps the request to a file system path that determines the response. The canonicalization routine that is used to map the request must correctly parse the URL to avoid serving or processing unexpected content.



This issue affects Web content owners who are running any version of ASP.NET on Microsoft Windows 2000, Windows 2000 Server, Windows XP Professional, and Windows Server 2003.

To know more about this issue and recommended guidance on best practices visit

http://www.microsoft.com/security/incident/aspnet.mspx

Wonder why GC has only 2 generations

The CLR Garbage Collector is a generational, mark-and-compact collector. It follows several principles that allow it to achieve excellent performance. First, there is the notion that objects that are short-lived tend to be smaller and are accessed often. The GC divides the allocation graph into several sub-graphs, called generations, which allow it to spend as little time collecting as possible. Gen 0 contains young, frequently used objects. This also tends to be the smallest, and takes about 10 milliseconds to collect. Since the GC can ignore the other generations during this collection, it provides much higher performance. G1 and G2 are for larger, older objects and are collected less frequently. When a G1 collection occurs, G0 is also collected. A G2 collection is a full collection, and is the only time the GC traverses the entire graph. It also makes intelligent use of the CPU caches, which can tune the memory subsystem for the specific processor on which it runs. This is an optimization not easily available in native allocation, and can help your application improve performance.

What Happens When a Collection Occurs?

Let's walk through the steps a garbage collector takes during a collection. The GC maintains a list of roots, which point into the GC heap. If an object is live, there is a root to its location in the heap. Objects in the heap can also point to each other. This graph of pointers is what the GC must search through to free up space. The order of events is as follows:

1. The managed heap keeps all of its allocation space in a contiguous block, and when this block is smaller than the amount requested, the GC is called.
2. The GC follows each root and all the pointers that follow, maintaining a list of the objects that are not reachable.
3. Every object not reachable from any root is considered collectable, and is marked for collection.

4. Removing objects from the reachability graph makes most objects collectable. However, some resources need to be handled specially. When you define an object, you have the option of writing a Dispose() method or a Finalize() method (or both). I'll talk about the differences between the two, and when to use them later.
5. The final step in a collection is the compaction phase. All the objects that are in use are moved into a contiguous block, and all pointers and roots are updated.
6. By compacting the live objects and updating the start address of the free space, the GC maintains that all free space is contiguous. If there is enough space to allocate the object, the GC returns control to the program. If not, it raises an OutOfmemoryException


With Best Regards,
Mitesh Mehta
Email : miteshvmehta@gmail.com
http://cc.1asphost.com/miteshvmehta/

OLAP Queries in .NET

This article Querying an OLAP datasource with C# shows how we can handle MDX queries with ADO.NET. This is achieved using ADOMD (Multi-dimensional) 2.7 with a runtime callable wrapper.

Its worth a read..

http://www.devhood.com/tutorials/tutorial_details.aspx?tutorial_id=640

I wonder if Microsoft has any plans to introduce managed provider for OLAP. That would be great!

To know more about MDX Query of SQL Server Analysis Services visit

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/olapdmad/agmdxbasics_0v7d.asp


With Best Regards,
Mitesh Mehta
Email : miteshvmehta@gmail.com
http://cc.1asphost.com/miteshvmehta/

How .NET generics work?

This white paper explains clearly on the working of .NET Generics

http://research.microsoft.com/projects/clrgen/generics.pdf

With Best Regards,
Mitesh Mehta
Email : miteshvmehta@gmail.com
http://cc.1asphost.com/miteshvmehta/

Creating Windows Service in .NET Framework

Windows services are applications that run outside of any particular user context in Windows NT, Windows 2000, or Windows XP. The creation of services used to require expert coding skills and generally required C or C++. Visual Studio .NET now makes it easy for you to create a Windows service, whether you're writing code in C++, C#, or Visual Basic. You can also write a Windows service in any other language that targets the common language runtime. This article walks you through the creation of a useful Windows service, then demonstrates how to install, test, and debug the service.

http://msdn.microsoft.com/msdnmag/issues/01/12/NETServ/default.aspx


With Best Regards,
Mitesh Mehta
Email : miteshvmehta@gmail.com
http://cc.1asphost.com/miteshvmehta/