Abstract: Timing facilities are used to provide sequence values that are unique across operating system images. A sequence value includes various components, including timing information and selected information. The selected information is used to provide a sequence value that is unique across a plurality of operating system images. Additionally, the sequence value can include, for instance, a processor identifier component and a placeholder component. The placeholder component ensures that the sequence value is an increasing value, even when the physical clock used to provide the timing information wraps back to zero.

Abstract: Controlling the flow of information between senders and receivers across links being used as channels. In one example, a self-timed interface link is adapted to be used as a channel. Such an interface is referred to as an integrated cluster bus. The flow control for the integrated cluster bus includes, for instance, a Data Request packet that indicates to the transmitter of data that it can now send the data; a continue indicator that specifies that more data is to follow; and a sequence indicator that is used to determine if a particular message is in proper sequence order. The integrated cluster bus does not require large data buffers and offers low latency messaging.

Abstract: Channel-to-channel communications is provided by integrating channel-to-channel functionality into one or more communication channels of a computing environment which may include heterogenous computer systems. The one or more channels having the integrated CTC function are non-dedicated channels also capable of conventional channel functionality. Work units at such channels are forwarded to either the CTC function or the channel function based on work unit type. Further, a facility is provided for automatically deciding which of the first channel and the second channel is to provide the CTC function for a CTC connection. Partition-to-partition communication can also be accomplished using the integrated CTC function by establishing an internal logical path between a first logical partition and the CTC function and a second logical path between a second logical partition and the CTC function.

Abstract: A method for a message processing system in which messages are transmitted from source nodes to destination nodes. A transmission flow control technique is disclosed in which the source node optimistically sends control information and a data portion of a message, and wherein a destination node discards the data portion of the message if it is unable to accommodate it. The destination node, however, retains enough of the control information to identify the message to the source node, and when the destination node is subsequently able to accommodate the data portion, the destination node issues a request to the source node to retransmit the data portion of the message. Discarding of one message is followed by discards of sequential messages, until the destination node is able to accommodate the data portions of messages.

Abstract: Program product for an application programming interface that unifies a plurality of mechanisms into a single framework. The interface includes a mechanism for communicating between members of a process group of related processes, and a mechanism for synchronizing the related processes of the process group. Additionally, the application programming interface may include mechanisms for managing membership of the process group or a processor group of processors, and/or a mechanism for controlling a group state value for the process group.