TAP provides packet reception and transmission for user-space programs. It can be viewed as a simple Ethernet device, which instead of receiving packets from a physical medium, receives them from a user-space program and instead of sending packets via physical media, writes them to the user-space program.
SetiContainer is a C++ class that allows convenient access to all the information in the state files of a SETI@home client. It periodically examines these files and updates its own data members accordingly. Other programs can use this class to extract information about the progress of the client, the found signals, or the work unit being processed. Additional functions offer more advanced info (like the amount of TeraFlops in a work unit, estimated time of completion, etc.). The SetiContainer class is based on the Qt toolkit, and extensively uses Qt's Signal/Slot technique.