Piranha: a CORBA tool for high availability

Despite the most careful planning, system applications can be dogged by unexpected failures. Our firm is keenly aware of the need for availability. To help meet that need, I developed an experimental CORBA-based restart service and monitor called Piranha, which both monitors and manages distributed applications to help systems attain high availability. First, Piranha acts as a network monitor that reports failures through a graphical user interface. Second, Piranha acts as a manager: it automatically restarts failed CORBA objects, replicates stateful objects (objects that maintain an internal set of values) on-the-fly, migrates objects from one host to another and enforces predefined replication degrees-numbers of copies-on groups of objects. As a backdrop to the discussion of Piranha´s design and implementation, this article first examines the ways in which a CORBA ORB should support availability. I then explain how Piranha affords availability