PARALLEL PROGRAMMING in C#

Make Data Matrix barcode in C# PARALLEL PROGRAMMING

namespace MFWindowApplication1 { public class Program : Microsoft.SPOT.Application {

There are a lot of ready-made exception classes in the .NET class library, but sometimes you will need to create an exception class that is specific to your program. You can easily do this by deriving from System.Exception.

in redo size in a NOARCHIVELOG mode database as the index CREATE and REBUILD operations are not logged in NOARCHIVELOG mode.

Declaring the variable of the class type allocates the memory to hold the reference, but not the memory to hold the actual data of the class object. To allocate memory for the actual data, you use the new operator. The new operator allocates and initializes memory for an instance of any specified type. It allocates the memory from either the stack or the heap, depending on the type. Use the new operator to form an object-creation expression, which consists of the following: The keyword new. The name of the type of the instance for which memory is to be allocated. Matching parentheses, which might or might not include parameters. I ll discuss more about the possible parameters later.

For example, the code in Figure 13-2 shows two equivalent declarations of enum TrafficLight. The code on the left accepts the default type and numbering. The code on the right explicitly sets the underlying type to int and the members to values corresponding to the default values.

Core Location is a framework included in the iPhone SDK that gives developers access to the device s current location. Before discussing how we used Core Location in Brightkite, it is worth discussing how a location fix may differ depending on what type of device is being used. An iPod Touch has only Wi-Fi network connectivity, so the device determines a location fix by querying a database of Wi-Fi access points, which are mapped to physical locations. I wouldn t want to drive around the world mapping Wi-Fi access points, but it has been done, and the database is impressively accurate. On the original iPhone, Wi-Fi can be supplemented with cellular telephone tower triangulation data. Triangulation is less precise than Wi-Fi, but it s adequate when Wi-Fi data is not available. A GPS radio integrated with the iPhone 3G lets Core Location provide a much more accurate location fix. Core Location is now widely used in thousands of iPhone applications. Typically, you might find the framework used in an applications such as an ATM finder, which offers a sorted list of ATMs with the closest location displayed at the top and the rest in descending order. Brightkite s use of location is a bit more sophisticated because the service revolves around a specific place, rather than geographical coordinates. To provide the precision expected by users, the correct place is displayed on the I am screen shown in the following illustration, which is the main tab used to perform check-ins or posts.

This chapter focused on the digital signing and encryption of SOAP messages in two directions: request and response. One-way signing and encryption (from the client to the service) is easier to implement, but this may create a significant security exposure. I also provided a discussion on the role of Certificate Authorities in certificate-based trusted relationships between clients and services, and I highlighted again the distinction between authenticated users versus authorized users. Security measures such as digital signatures and encryption enable services to authenticate clients. However, authenticated clients are not necessarily authorized to access the full capabilities of a given Web service. The topic of authorization is discussed in the next chapter. Finally, I closed with a discussion of replay attacks, which are a form of denial-of-service (DoS) attack. The risk of replay attacks can be minimized if the Web service correlates incoming request messages and verifies their uniqueness prior to processing them.

The BusinessBase class implemented in 3 includes support for validation rules. Each rule is a method with a signature that conforms to the RuleHandler delegate. A business object can implement business rules conforming to this delegate, and then associate those rule methods with the properties of the business object. Most applications use a relatively small, common set of validation rules such as that a string value is required or has a max length, or that a numeric value has a minimum or maximum value. Using reflection, it is possible to create highly reusable rule methods which is the purpose behind the Csla.Validation.CommonRules class. Obviously, using reflection incurs some performance cost, so these reusable rule methods may or may not be appropriate for every application. However, the code reuse offered by these methods is very powerful, and most applications won t be adversely affected by this use of reflection. In the end, whether you decide to use these rule methods or not is up to you.