WAIPSessionTrackingStrategy > isAbstract   ^true has just ran into my new hobby horse. I am reading through every class in Seaside to document it and I had an 'aha!' moment on the design of Abstract super classes like WABrush: WABrush > isAbstract       ^ self == WABrush The simplicity is genius because no subclass of WABrush has to implement isAbstract, whereas in WAIPSessionTrackingStrategy, concrete subclasses (of which there currently are none) will have to. In defense of the WAIPSessionTrackingStrategy implementation, the comment reads: I track sessions using the remote address of a client. Usually you don't want to use this because it causes troubles when multiple users share the same IP (eg. several users from the same company). That's why I'm marked as abstract. There are some special cases like crawlers where it can work though.  So, apparently, the author is anticipating somebody someday using it.