Designing Microsoft ASP.NET Applications in c sharp

Printer data matrix barcodes in c sharp Designing Microsoft ASP.NET Applications

5 . . Experiment with changing the dates and times to see how setting the expiration time forces a reload of the cache . An absolute expiration time applied to the cached item tells ASP .NET to flush the item from the cache at a certain time . Now try using a different kind of expiration technique the sliding expiration . Using a sliding expiration tells ASP .NET to keep the data in the cache as long as it has been accessed within a certain period of time . Items that have not been accessed within that time frame are subject to expiration .

END CONVERSATION @dialog WITH CLEANUP;

L2TP/IPSec connections, unlike those of PPTP, require computer authentication in addition to user authentication. Computer authentication is performed first; this pro cess occurs during all L2TP/IPSec connection attempts between remote access clients and servers. After the tunnel endpoints are authenticated and a secure channel is estab lished between the client and the server, user authentication follows. User authentica tion over L2TP/IPSec VPN connections occurs by means of any of the same set of authentication protocols that are used for PPTP and dial-up connections. Once user authentication is complete, user authorization follows. Computer Certificates and L2TP/IPSec For most L2TP-based VPN connections, com puter authentication is performed by means of a certificate infrastructure. To successfully implement this type of VPN, you must install computer certificates issued by the same certificate authority (CA) on each VPN client and VPN server. If you are using a Windows Server 2003 enterprise CA as an issuing CA, you should configure your Active Directory domain for autoenrollment of computer certificates by using the Computer Configuration group policy. Through this method, each computer that is a member of the domain automatically requests a computer certificate when the Computer Configu ration group policy is updated.

Figure 4-14: The code can be used to change the value of the forecolor attribute from blue to black. Adding and Deleting Nodes A source XML document can also be easily read and modified by adding or deleting nodes. Let's look at a couple of examples. To add a new node, you simply read until the parent is found and then write an extra set of nodes to the XML writer. Because there might be other nodes with the same name as the parent, use a Boolean guard to ensure that the insertion takes place only once. The following code demonstrates how to proceed: void AddUser(string name, string pswd, string role) { XmlTextReadWriter rw; rw = new XmlTextReadWriter(inputFile, outputFile); rw.WriteStartDocument(); // Modify the root tag manually rw.Writer.WriteStartElement(rw.Reader.LocalName); // Loop through the document bool mustAddNode = true; // Only once while(rw.Read()) { switch(rw.NodeType) { case XmlNodeType.Element: rw.Writer.WriteStartElement(rw.Reader.LocalName); if ("Users" == rw.Reader.LocalName && mustAddNode) 158

Sample of Visual Basic Code Dim addressControl As AddressUc = _ CType(LoadControl("AddressUserControl.ascx"), AddressUc) form1.Controls.Add(addressControl) Sample of C# Code AddressUc addressControl = (AddressUc)LoadControl("AddressUserControl.ascx"); form1.Controls.Add(addressControl);

The ALTER SESSION command provides another convenient way to save you the effort of prefixing object names with their schema name, but without using synonyms. This is another convenience feature, just like synonyms.

ths s a test Here you ve substituted all occurrences of the letter 'i' with an empty string. What about more complex patterns Simply matching the letter 'i' is not a true example of a regular expression. For example, let s say you want to replace the first two characters of a string with 'Hello': x = "This is a test" puts x.sub(/^../, 'Hello')

Remote access connections must be configured for users who connect to a Windows network from a nonlocal site. The two basic methods for remote access include direct dial-up to a network computer and virtual private networks. For dial-up access, you must not only configure a server to answer incoming calls, but you must also configure authentication, access permissions, and encryption requirements. VPNs enable private connections to cross a public network such as the Internet. These network connections require a different set of configuration procedures for authentication, encryption, and security.

// Displays "Richter" // Displays "Jeffrey"

If you compile the code above into a library (DLL) assembly and look at the result by using ILDasm .exe, you ll see what is shown in Figure 6-2 . As you can see in Figure 6-2, defining a class by using the static keyword causes the C# compiler to make the class both abstract and sealed . Furthermore, the compiler will not emit an instance constructor method into the type . Notice that there is no instance constructor (.ctor) method shown in Figure 6-2 .

System.Web.UI.Control type also uses the following technique to reduce the memory wasted by unused events. By explicitly implementing the event s add and remove methods creatively, you can greatly reduce the amount of space wasted by each object. In this section, I ll show you how to define a type that exposes many events efficiently. The basic idea is that each object will maintain a collection (usually a hash table) of event/delegate pairs. When a new object is constructed, this collection is empty. When interest in an event is registered, the type of event is looked up in the collection. If the event is there, the new delegate is combined with the linked list of delegates for this event. If the event isn t identified in the collection, the event is added with the delegate. When the event needs to fire, the event is looked up in the collection. If the collection doesn t have an entry for the event, then nothing has registered interest in the event and no delegates are called back. If the event is in the collection, then the delegate linked list associated with the event is invoked. The following code demonstrates the recommended design pattern that should be used to design a type that defines lots of events:

At this point, the thread is executing code and manipulating data in its process s address space . After another time-slice, Windows performs another context switch . Windows performs context switches from the moment the system is booted and continues until the system is shut down . Windows is called a preemptive multithreaded operating system because a thread can be stopped at any time and another thread can be scheduled . As you ll see, you have some control over this, but not much . Just remember that you cannot guarantee that your thread will always be running and that no other thread will be allowed to run . Note Developers frequently ask me how they can guarantee that their thread will start running