barcode printing vb.net Other Garbage Collector Performance Issues in .NET

Encoding Code 39 in .NET Other Garbage Collector Performance Issues

Since the static classes can have any name you want, it takes the C# compiler time to find extension methods as it must look at all the file-scope static classes and scan their static methods for a match . To improve performance and also to avoid considering an extension method that you may not want, the C# compiler requires that you import extension methods . For example, if someone has defined a StringBuilderExtensions class in a Wintellect namespace, then a programmer who wants to have access to this class s extension methods must put a using Wintellect; directive at the top of his or her source code file .

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The Win32 API offers many functions that execute I/O operations . Unfortunately, some of these methods do not let you perform the I/O asynchronously . For example, the Win32 CreateFile method (called by FileStream s constructor) always executes synchronously . If you re trying to create or open a file on a network server, it could take several seconds before CreateFile returns the calling thread is idle all the while . An application designed for optimum performance and scalability would ideally call a Win32 function that lets you create or open a file asynchronously so that your thread is not sitting and waiting for the server to reply . Unfortunately, Win32 has no CreateFile-like function to let you do this, and therefore the FCL cannot offer an efficient way to open a file asynchronously . Here is an example where this is a real problem . Imagine writing a simple UI control that allows the user to type a file path and provides automatic completion (similar to the common File Open dialog box) . The control must use separate threads to enumerate directories looking for files because Windows doesn t offer any functions to enumerate files asynchronously . As the user continues to type in the UI control, you have to use more threads and ignore the results from any previously spawned threads . With Windows Vista, Microsoft introduced a new Win32 function called CancelSynchronousIO . This function allows one thread to cancel a synchronous I/O operation that is being performed by another thread . This function is not exposed by the FCL, but you can also P/Invoke to it if you want to take advantage of it from managed code . I show the P/Invoke signature for it in the next section of this chapter . The point I want you to take away though is that many people think that synchronous APIs are easier to work with, and in many cases this is true . But in some cases, synchronous APIs can make things much harder . Microsoft s Windows team is looking at the synchronous-only APIs and deciding which function needs to be exposed with asynchronous APIs in future versions of Windows . Once they do this, the FCL will expose this functionality, too . You can always call any method asynchronously via a delegate s BeginInvoke method, but when you do this, you are using a thread, so you are losing some efficiency . And actually, you can t use a delegate to call a constructor . So the only way to construct a FileStream object asynchronously is to call some other method asynchronously and have this other method construct the FileStream object . Windows doesn t offer functions to asynchronously access the registry, access the event log, get a directory s files/subdirectories, or change a file s/ directory s attributes, to name just a few .

Superscope Supporting Remote Multinets Figure 7-8 illustrates a configuration used to support multinets on a physical network (Subnet B) that is separated from the DHCP server. In this scenario, a superscope defined on the DHCP server joins the two multinets on a remote segment beyond the router. Because DHCP traffic is normally restricted to the local subnet, a DHCP relay agent is used to support clients on the remote segment.

Interface Name: Contoso Connection Type: Connect Using Virtual Private Networking (VPN) VPN Type: Layer 2 Tunneling Protocol (L2TP) Destination Address: 207.209.68.1

in the Details pane, relevant task links appear in the bottom of the Action pane. Up arrows and down arrows let you expand or contract a section of the Action pane; clicking a right arrow displays a submenu. The vertical split bar between the panes can be dragged to the left or right, like its counterpart in Windows Explorer. To display or hide the console tree or the Action pane, use the toolbar buttons (one controls each pane) or the Customize command on the View menu.

Query the table T1:

Windows Identity Foundation (WIF) and Windows Communication Foundation (WCF) will take care of decrypting and validating the SAML token. The claims will be added to the ClaimsPrincipal object and the principal will be added to the WCF security context. The WCF security context will be used in the authorization manager by checking the incoming claims against the operation call the client wants to make.

You can also optionally define a command parameter by using the CommandParameter property. You specify the type of the expected argument in the Execute and CanExecute target methods. The control will automatically invoke the target command when the user interacts with that control, and the command parameter, if provided, will be passed as the argument to the command s Execute method. In the preceding example, the button will automatically invoke the SubmitCommand when it is clicked. Additionally, if a CanExecute handler is specified, the button will be automatically disabled if CanExecute returns false, and it will be enabled if it returns true. An alternative approach is to use Expression Blend interaction triggers and Invoke CommandAction behavior, as shown in the following example.

piFailCount piIgnoreCount ; }

public static class Monitor { public static Boolean Wait(Object obj); public static Boolean Wait(Object obj, Int32 millisecondsTimeout); public static void Pulse(Object obj); public static void PulseAll(Object obj); }

The native sockets interface is a managed code wrapper around the WinSock32 API, exposing the underlying socket system of the Windows operating system. For the most part, the .NET socket classes simply provide a one-to-one wrapper around the unmanaged code. Java programmers are used to working with sockets at a higher level. The .NET socket classes allow for absolute control over Windows-based network programming but achieve this with increased complexity and demand a deeper understanding of network programming from the developer.

Comments The platform-specific separator character. Defaults to \ for Windows. Provides a platform-specific array of characters that are InvalidPathChars illegal in path names. Provides a platform-specific path separator character. PathSeparator Defaults to ; for Windows. Provides a platform-specific volume separator character. VolumeSeparatorChar Defaults to : for Windows. Changes the extension of a path string. ChangeExtension() Concatenates two path strings. Combine() Gets the contents of a path string between the first and last GetDirectoryName() instances of DirectorySeparatorChar. Returns the extension of a path string, including the period. GetExtension() Returns the contents of a path string after the last instance of GetFileName() DirectorySeparatorChar. GetFileNameWithoutExtension() Returns the contents of a path string after the last instance of DirectorySeparatorChar and before the last period. Returns a fully qualified path for a partial path string. If the GetFullPath() partial path begins with the directory separator character, the result will be prepended with <default drive>:; otherwise, the result will be the current working directory plus the partial path name. Returns the root for a path string. GetPathRoot() Creates a zero-length temporary file with a unique path, GetTempFileName() which is returned as the result. GetTempPath() Returns the path of the current system's temporary directory. Returns true if the path string contains the period character HasExtension() followed by at least one other character. Returns true if the path is fully qualified. IsPathRooted()