anager for Objects Resources Successful (Resources) Installation Figure 2.4a-9 Simplified ApplicationFactory create() call for the creation of a waveform. The software defined radio as a platform for cognitive radio CHAPTER 2.4a connects all the Resources, and informs the Domain- reestablishes the previous configuration before shut- Manager (a master controller discussed in see section down, and waits for incoming requests. These requests System Control) that the waveform was successfully can be DeviceManagers associating with the Domain- created. The other steps in this creation process, such as Manager, or new Applications launched by the Appli- initializing the Resources, are not included in this de- cation Factory. scription for the sake of brevity. Once the Applica- tionFactory has completed the creation process, Putting it together a waveform comprising a variety of connected compo- In general, the boot-up sequence of an SCA radio is nents now exists and can be used by the system. partitioned into two different sets of steps, Domain boot-up, and one or more Device boot-ups. Once the Application class platform has been installed (i.e., file system(s) and de- The ApplicationFactory returns to the caller an instance vice(s)), the system is ready to accept requests for new of the Application class. The Application class is the waveforms. These requests can arrive either from the handle that is used by the environment to keep track of user or from some other entity, even a cognitive engine. the application. The Application class inherits from the Figure 2.4a-11 shows a simplified boot-up sequence for Resource class, and its definition does not add any more the different parts of the SCA radio. function calls, just application identifiers and descriptors. The instance of the Application class that is returned by Profiles the ApplicationFactory is the object that the user would The SCA is composed of a variety of profiles to describe call start, stop, and releaseObject on to start, stop, and the different aspects 