CHAPTER 6 DECOUPLED NAVIGATION PATTERN Let s continue (Windows 2003 server web)
CHAPTER 6 DECOUPLED NAVIGATION PATTERN Let s continue building on this example. Imagine that the same user interface is used to make a remote call via the XMLHttpRequest object. Figure 6-12 illustrates the steps needed in the remote case. Figure 6-12. Steps resulting from clicking a button when using an extra XMLHttpRequest call Figure 6-12 shows an added step (step 2), in which a request is made by using the XMLHttpRequest object that then generates some data that is processed in step 3. Looking at Figures 6-11 and 6-12, you might be wondering where the need for the Common Data functionality is. The need arises because often an application is converted from the state depicted in Figure 6-11 to that in Figure 6-12, or vice versa. Implementing the conversion can require some major restructuring of the code, or a completely new implementation that needs to be tested and maintained. The Common Data functionality decouples the steps so that an application that executed as in Figure 6-11 could be converted without major surprises into an application that executes as in Figure 6-12. The intention is to decouple, allowing the fewest number of changes and yielding the largest user benefit. Consider the following code, which mimics the implementation of Figure 6-11: function OnClick( event) { document.getElementById( “myDiv”).innerHTML = “data”; } The code is a problem because what was defined as two steps in Figure 6-11 is one step in technical terms. The code is a function with an implementation. The problems of the function OnClickare that the text identifier myDiv is hard-coded, and so is the assigned value data. Imagine that the assignment code is used in multiple places, and imagine that the text has to be converted to uppercase before doing the assignment. Then the code would have to be updated in multiple places.
We recommend cheap and reliable webhost to host and run your web applications: Coldfusion Web Hosting services.