create qr code vb.net BUS INE SS AND V ALIDA TION RULES in visual basic

Encoding QR Code JIS X 0510 in visual basic BUS INE SS AND V ALIDA TION RULES

disassembler show the actual byte values constituting the IL flow.) Find the check methods in the tree views of both instances of ILDASM, and double-click them to open disassembly windows, in which you can compare the two implementations of the same method to see whether the code compaction worked.

In 20, you will see how to implement an ASP.NET Web Forms UI on top of business objects. This chapter makes use of the data binding capabilities introduced in Web Forms 2.0. In this technology, the Insert and Update operations provide the data from the form in IDictionary objects (name/value pairs). The values in these name/value pairs must be loaded into corresponding properties in the business object. You end up writing code much like this: cust.Name = e.Values["Name"].ToString(); cust.Address1 = e.Values["Address1"].ToString(); cust.City = e.Values["City"].ToString(); Similarly, in 21, you ll see how to implement a WCF service interface on top of business objects. When data is sent or received through a web service, it goes through a proxy object, an object with properties containing the data but no other logic or code. Since the goal is to get the data into or out of a business object, this means copying the data from one object s properties to the other. You end up writing code much like this: cust.Name = message.Name; cust.Address1 = message.Address1; cust.City = message.City; In both cases, this is repetitive, boring code to write. One alternative, though it does incur a performance hit, is to use reflection to automate the copy process. This is the purpose of the DataMapper class: to automate the copying of data to reduce all those lines of code to one simple line. It is up to you whether to use DataMapper in your applications.

Having understood the big picture, let s get started building a WCF state machine workflow that supports HttpWebRequest. In order to be consistent, we use the shopping cart example we used in the previous exercise.

In this example, it wasn t necessary to use a property, and the resulting design turned out elegant and maintainable. The problem is that the code is a wrapper for a property called Temperature. Look at the big picture and consider where the oven temperature comes from. Most likely the temperature comes from a device driver that interfaces with the oven. And that device driver exposes a property that represents the temperature oven. The reason why I make this assertion is that to generate an event in software, the state has to exist somewhere. And a state is represented as a property of something. In other words, the solution presented to you is a really nifty wrapper to a property. A cynical reader could say, Great, you managed to complicate something simple by adding pointless layers of abstraction. The layers aren t complications, because they decouple pieces of the application from each other. Imagine if the oven had two sensors, not just one. If a property were read directly, all of the code would have to be modified to read two properties. Worse yet, how do you combine the readings of two properties Is it an average, lowest, or highest You don t know as it s an application that must be implemented. Using the example of layers, the logic of a single or multiple temperature sensors is entirely encapsulated within the Oven class. If I were involved in a code review, and somebody handed me a design for an oven with a property called temperature, I probably wouldn t accept the design, but depending on other conditions, might accept the design. Additionally, though it wasn t covered, the temperature shouldn t be a double value, but should be a type called temperature. This is a problem that can be spelled out in two words: Mars Lander. The Mars Lander failed because one team performed its calculation using imperial measurements, and the other team performed calculations using metric. As a result, the Mars Lander crashed. Hence the correct design would be a property or delegate where the temperature is exposed as type Temperature. Overall though, using properties stops the developer from implementing separation of concerns. Separation of concerns is increasingly on the programmer s radar. Given the growing range of data access products and platforms, it s now essential to separate data producers from data consumers. The Observer pattern provides a simple but powerful model for achieving this crucial design goal.

Overview of the WS-Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96 Introducing Web Services Enhancements 2.0 . . . . . . . . . . . . . . . . . . . . .102 Install and Configure WSE 2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110 X.509 Certificate Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114 Final Thoughts on WSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121

Save the class and compile the application. Open Workflow1.xaml. Drag a WriteLine activity beneath the green circle and change the Display Name to What is your age and set the Text to What is your age

class B: A { public int Field2; } class Program { static void Main( ) { B myVar1 = new B(); Return the reference to myVar1 as a reference to a class A. A myVar2 = (A) myVar1; Console.WriteLine("{0}", myVar2.Field1); Console.WriteLine("{0}", myVar2.Field2); myVar2 can t see Field2. // Fine // Compile error!

This approach has the maintenance and code-reuse flaws that I ve talked about, but the fact is that it gives pretty good performance in most cases. Also, it doesn t hurt that most programmers are pretty familiar with the idea of writing code to manipulate a DataSet, so the techniques involved are well understood, thus speeding up development. A decision to stick with an object-oriented approach should be undertaken carefully. It s all too easy to compromise the object-oriented design by taking the data out of the objects running on one machine, sending the raw data across the network, and allowing other objects to use that data outside the context of the objects and business logic. Such an approach would break the encapsulation provided by the logical business layer. Mobile objects are all about sending smart data (objects) from one machine to another, rather than sending raw data. Through its remoting, serialization, and deployment technologies, the .NET Framework contains direct support for the concept of mobile objects. Given this ability, you can have your Data Access layer (running on an application server) create a business object and load it with data from the database. You can then send that business object to the client machine (or web server), where the UI code can use the object (as shown in Figure 1-16).