Message passing between computer systems

A method and means for exchanging messages between a multitude of computer systems is provided, whereby the sender system's memory is used as a buffer for the message to be transferred. The method comprises a first step of writing data into a portion of the sender system's memory, a second step of setting an indication signal in the receiver system, and a third step of performing a remote read access to the data in the sender system's memory. Thus, the message buffers of prior art solutions have been replaced by portions of the sender system's memory. The remote read access is performed by a direct memory adapter (DMA) in the receiver system, whereby said indication signal is mapped to the start address of said portion of the sender system's memory. Because any write access to a remote system's memory is forbidden, data integrity is preserved.