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Bandwidth Checker
Until the release of FMS3, the only way to check your system's current bandwidth was with server-side code and algorithms that would extract bandwidth based on pings or some similar measure. A very interesting new feature is a call to the server, checkBandwidth. Because the call is to a built-in function, you can check your bandwidth with client-side code. The checkBandwidth command is invoked with a call to the method from a NetConnection object:
//nc is a NetConnection instance
nc.call ("checkBandwidth",null);
It looks exactly like a call to a server-side function, but with the checkBandwidth method, you don't write any server-side code. While you don't write the method, it still belongs to the server-side Client class. You have to write a special class to get the returned information using two specific methods, named onBWCheck and onBWDone. The class is invoked as a NetConnection.client instance.
6.6.1. Setting Up the Client Class
The first step is to write a client class that contains the methods required to check the bandwidth and return a value. Also, by including a public getter method, you can get the returned bandwidth for your main class. The client class can go into the same file as your main class; but by keeping it separate, it can be easily identified and reused for any application where you need to get the bandwidth. To get started, create the BWClient.as file shown in Example 6-10. It is the class to be instantiated by the NetConnection.client instance.
The ...(rest) parameter accepts any number of comma-delimited arguments. The first method, onBWCheck returns a 0 because it has to return something. Its role is to start the ball rolling on the call to NetConnection.call("checkBandwidth", null). The key method in this class is the one that recognizes that the operation is completed, onBWDone. The rest[0] element contains the current bandwidth speed in kilobits. To be able to do something in the main class, the sendInfo() method is a public one that is used to retrieve the current bandwidth by the main class.
Next, the CheckBW class calls the client class (BWClient), extracts the bandwidth, and shows the user what it is. Of course, the bandwidth could be used to do anything from adjusting the camera and sound settings, to making other adjustments to optimize a FMS3 application. Enter the code in Example 6-11 and save it as CheckBW.as.
The CheckBW class calls the checkBandwidth method as soon as the connection is established. However, to see what the bandwidth is, the user clicks a button that calls the showBW method. It uses the BWClient instance (nc.client) to call the getter method, sendInfo(). Using an object instance property (checkUp.see), the program stores the returned bandwidth value and passes it to a numeric variable, currentBW. In turn, the information is passed to a text field for the user's information.
One of the interesting features is that even though the checkBandwidth method is called as soon as a connection is established, it takes a while for the bandwidth information to be returned to the client. So the output message in the text field advises the user to be patient and give the button another click if the process is incomplete. Figure 6-12 shows the output before and after the bandwidth value has been returned.
As you can see in the CheckBW class, the RTMP connection is to the same application that has been used with the other applications in this chapter (studio). However, you can use it with any application simply by using the same RTMP address.
