Each servlet must define a function for the HydraExpress servlet container to use to load the servlet. The RWSF_DEFINE_SERVLET macro takes the name of the servlet class as an argument and expands to an appropriate function. For the HelloWorldExample servlet, the servlet class is named HelloWorldExample. Therefore, the servlet implementation file contains the line below:

Since the macro expands to a function, the macro must appear in only one file for each servlet. For more details on the macro, see Defining Filters, Servlets, and Listeners.