Group communication is playing an increasingly important role in distributed applications including web based applications for many forms of cooperative and interactive works. The real-time publication/subscription communication model [6] is a variance of group communication model that support hard real time communications needed in real time applications such as automatic control. It was initially developed in the context of Simplex architecture [7] to facilitate the online replacement of software component. Similar real time event services can be found in real time CORBA.Many real-time systems, e.g., telephone switching and manufacturing systems, have high availability requirements. In this paper, we present a fault tolerant architecture extension that will improve the reliability of the real time P/S service. This work is done in the context of duplex hardware architecture that is commonly used in manufacturing and communication systems.Real-time publisher/subscriber model uses channels as its basic communication units. Each channel has a unique name in the distributed system. It also has multiple message senders (publishers) and multiple message receivers (subscribers). And each subscriber of a channel can receive any message from the channel's publishers. Channels, publishers and subscribers are decoupled. User level application should require the publication (subscription) rights before it can send (receive) messages from a channel.Architecturally, real time P/S is partitioned into two parts: 1) the P/S server for the creation and deletion of channels, publishers and subscribers and 2) the publication and subscription of real time data. The P/S server manages the communication channels on a two-dimensional linked lists. Each channel has a list of publishers and a list of subscribers. To minimize the communication overhead, each publisher is given a copy of the list of its subscribers, so that the publisher can directly send the data to its subscribers.P/S servers mainly perform three function: 1. Channel management: Clients can request to create a new channel, delete a channel, get or relinquish the publication/subscription rights.2. Update management: In P/S model, channels are distributed. Publishers or subscribers may exist in several nodes. When a new publisher/subscriber is added into the channel, we should notify all the other IPC servers about the update. Then P/S servers modify their data structure and notify local clients.3. Delivery management: Direct message passing from publisher to subscriber makes communication faster, but it also cause a message to be sent to a remote node several times, if several subscribers exist in that node. To reduce the data traffic between nodes, a message is sent to each node once, and the IPC server in that node is responsible for delivering the message to its local subscribers.Finally, the user-level library offers three services: 1. To translate the call of user application to create/delete channels or get/relinquish P/S rights into requests, and send them to IPC server.2. To deliver messages according to the cached channel table in its own address space.3. To update the cached channel table to be consistent with global table.In section 2, we will present the fault tolerant extension of the real time P/S model. In section 3, we will review how to schedule P/S service as a software real time task in the context of real time control applications. Section 4 provides the conclusion.