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n most cases, extending the .NET Remoting infrastructure means creating classes that implement specific interfaces of the framework. Within this appendix, you ll find a brief description of the interfaces needed for extending the .NET Remoting framework with your own channels and formatters, as well as message sinks. Some of the interfaces you ll find in this appendix might have been described in the previous appendix, too, but from within another context. The namespaces where you can find the interfaces described in this appendix are as follows: System.Runtime.Remoting.Messaging System.Runtime.Remoting.Activation System.Runtime.Remoting.Proxies System.Runtime.Remoting.Channels You can find details about the interfaces and how to use them in the chapters of the second part of the book.

Finally, click the Back button again. Since you have navigated past the first page of the application, the application is terminated, triggering the Application_Closing event and printing the corresponding message in the Output window.

Figure 7-2. Creating a custom activity The implementation of this class is shown in Listing 7-1. Listing 7-1. LookupItem Class using System; using System.Activities; namespace OrderProcess { public sealed class LookupItem : CodeActivity { public InArgument<string> ItemCode { get; set; } public OutArgument<ItemInfo> Item { get; set; } protected override void Execute(CodeActivityContext context) { ItemInfo i = new ItemInfo(); i.ItemCode = context.GetValue<string>(ItemCode); switch (i.ItemCode) {

In other words, BASH had interpreted each word as a separate file and tried to move each of them! The error messages tell us that BASH cannot find the file picture, from, or germany.jpg. There are two solutions. The easiest is to enclose the filename in quotation marks ("), so the previous command would read as follows: mv "picture from germany.jpg" mydirectory/ The other solution is to precede each space with a backslash. This tells BASH you re including a literal character in the filename. In other words, you re telling BASH not to interpret the space in the way it normally does, which is as a separator between filenames or commands. Here s how the command looks if you use backslashes: mv picture\ from\ germany.jpg mydirectory/ The backslash can also be used to stop BASH from interpreting other symbols in the way it normally does. For example, the less than and greater than symbols (<>) have a specific meaning in BASH, which we discuss in 17, but they re allowed in filenames. So to copy the file <bach>.mp3 to the directory mydirectory, you could type: cp \<bach\>.mp3 mydirectory/ Generally speaking, however, simply enclosing filenames in quotation marks is the easiest approach.

A couple of the design parameters you will have to decide upon when developing your processor-driven accessory will be what speed to operate the processor chip and what voltage level to provide. Modern processors can operate on a range of voltages typically from something as low as 2.0 volts up to 5.0 volts. Most often, you will choose something around the 3.0-volt level that is normal for these types of designs. There are other considerations as well. Have you ever looked up the voltage of an iPhone battery Nuf said. Another consideration is at what clock speed you will run your processor chip. The off-thetongue answer is as fast as possible. That answer lasts for about a minute until you realize that the faster the speed the more power consumed. Processor speed selection isn t an arbitrary decision. You have to consider other clock speeds within your system. For example, take an RS232 serial connection to some device. Unlike a desktop computer, where you can pretty much set any speed on your modem, a microcontroller is different. You are generally limited to a small set of connection speeds. What s more, some of the speeds will be more accurate than others. For example, you might run 19.2 kbps with a 2.5% error but have an error of 5.5% if you run the connection at 9600 bps. The serial connection speed is derived from multiples (or subdivisions) of the processor s clock speed. This means that you may have to work backwards from your specific rate requirements (e.g., serial speed) to get to your clock speed. If you need a 19.2 kbps clock at less than 2.0%, you look up in the processor s specification which processor clock speed can provide that accuracy. So it s not an arbitrary decision. Also, be sure to check all processor I/O that requires deterministic clock speeds. For example, you could have two serial connections, maybe an RS232 and a SPI interface. Once you find a set of rates and accuracies that work, you ll have your processor s clock. To get the processor s clock, you had to derive it from the requirements for any other clock derived interfaces. Your purpose in deriving the clock speed was to determine power requirements. Now that you have selected a voltage source (level) and a clock speed, you can determine the amount of current your accessory will draw. NOTE: Clock speed of the processor can really drive your design, even going as far as forcing you to switch to a different model or even a different family of chips. Some processors have an internal oscillator that provides a clock you can use without adding parts such as external RC networks or crystals that drive up power and cost. On the other hand, internal oscillators tend to be less accurate. That loss of accuracy can trickle down to parts of your system where a specific speed must be met. Like anything, it s a trade-off. Now that power and clock speed have been dealt with, the next thing to consider is I/O. Processors generally provide increasing amounts of digital I/O along their family lines. As I/O pins increase, so does the number of pins on the device that causes it to get larger. The PIC16F690 I use comes in a 20-pin package, and you saw how small it was by looking at Figure 10 6. Basically, every pin except power and ground is (or can be

var browser = Observable.FromEvent<System.Windows.Navigation.NavigationEventArgs>(webResults, "Navigated"); browser.ObserveOn(Deployment.Current.Dispatcher).Subscribe(evt => { loadingImages.Stop(); lblLoading.Visibility = System.Windows.Visibility.Collapsed; }); You are now ready to run the application. 10. Press F5, type a keyword into the text box, and observe the animation while the images are being loaded into the browser. While we have only scratched the surface of Rx.NET and its applications, you can already see how powerful this framework is. Using Rx.NET, you can think of virtually any event as an observable data source, whether it s a location service that generates coordinate values (which you can think of as an observable set of position values) or accelerometer data, or key press events, or web browser events, such as those already demonstrated. Now that you have seen how to create Observable data sources from events using the FromEvent<T> keyword and how to subscribe to those events, we will expand upon

The major drawback to freelist groups is that you cannot change the number of freelist groups without rebuilding the object. So if you ve carefully matched the number of freelist groups to the number of instances in your system, you have a reorganization problem when you decide to add a couple of nodes to the system. Remember to plan for growth.

One of the core functions you ll find most useful when you re creating new documents is the wizard system, which you can access from the File menu. A wizard guides you through creating a new document by answering questions and following a wizard-based interface. This replaces the template-based approach within Microsoft Office, although it s worth noting that OpenOffice.org is still able to use templates. A wizard will usually offer a variety of document styles. Some wizards will even prompt you to fill in salient details, which they will then insert into your document in the relevant areas.