Computer node architecture comprising a dedicated middleware processor
The computer node architecture provides a separate computer for the execution of the respective one of the application software and the middleware software, with an interface precisely defined in the time and value range provided between said two computers, and thus to decouple largely these two subsystems so that development is improved and the time needed for real-time applications better foreseeable.
1. A multicomputer node computer for a distributed computer system comprising the following units:
at least one host computer ( 140 , 240 ) with a dedicated CPU and a dedicated memory, at least one middleware computer ( 120 , 220 ) with a dedicated CPU and a dedicated memory, and at least one communication system ( 101 ) connected to the middleware computer ( 120 , 220 ) and, by way of at least one communication channel, with other node computers of the distributed computer system, an interface ( 230 ) being provided between said host computer ( 240 ) and said middleware computer ( 220 ), said interface comprising a dual access memory (DPRAM) to which the middleware computer ( 220 ) accesses in reading or in writing during time intervals specified beforehand and to which the host computer ( 240 ) can access in reading or in writing out of these time intervals specified beforehand, the interface ( 230 ) between the host computer ( 240 ) and the middleware computer ( 220 ) including additionally a distinct memory cell, a time cell ( 231 ), into which the middleware computer ( 220 ) periodically writes the actual time, wherein the communication system ( 101 ) builds up a global time and that the content of the time cell ( 231 ) in the interface ( 230 ) between host computer ( 240 ) and middleware computer ( 220 ) is periodically updated directly by a local communication controller ( 200 ) of the communication system by way of a hardware signal line ( 221 ) and wherein the middleware computer is dedicated to performing administrative tasks by way of executing a set of middleware software and synchronizing memory access with the host computer such that the host computer can be dedicated to the execution of application software in a deterministic fashion without interferences of the middleware computer and the communication system.
2. The node computer of claim 1 , wherein another storage place ( 232 ), into which the host computer ( 240 ) can enter a time value and in which hardware can generate an interrupt signal for the host computer ( 240 ) as soon as the content of the time cell ( 231 ) corresponds to the time value in said another storage place ( 232 ), is present in the interface ( 230 ) between said host computer ( 240 ) and said middleware computer ( 220 ).
3. The node computer of claim 1 , wherein the middleware computer ( 220 ) enters a global time from an external time base.
4. The node computer of claim 1 , wherein the host computer ( 240 ) used is a commercial-off-the shelf (COTS) computer which is connected to the middleware computer by way of a standard interface.
5. The node computer of claim 1 , wherein the interface ( 230 ) between middleware computer ( 220 ) and host computer ( 240 ) is configured as a serial communication interface by way of which, at times determined beforehand, the middleware computer ( 220 ) sends messages that contain, in a distinct address, the actual time value ( 231 ).
6. The node computer of claim 1 , wherein, in introducing fault-tolerance by replication of the node computers, neither the time behavior nor the values behavior of the interface ( 230 ) between middleware computer ( 220 ) and host computer ( 240 ) are altered as compared to a non-fault tolerant configuration.