A special checkpointing object method based primary-passive TMO replication scheme and middleware support

The PPTR (primary passive TMO replication) scheme is a passive real-time object replication scheme, which is based on the TMO (time-triggered message-triggered object) real-time object model. Compared to the active object replication schemes, the passive object replication schemes typically require fewer processor resources, but have longer fault recovery times. This paper describes a relatively simple and somewhat restrictive but still quite broadly applicable version of the PPTR scheme and its implementation into a real-time middleware architecture, ROAFTS. The PPTR scheme is compared against another existing active real-time object replication scheme supported by the ROAFTS middleware architecture.