Abstract: Techniques employed in displays of graphs with large numbers of nodes for viewing details of an area of interest while preserving context. The techniques take advantage of parent-child and sibling relationships. Sibling nodes and children of sibling nodes are displayed in rows. The center of interest is at the center of a row and nodes at the ends of the rows overlap. A parent node may have a node scroller associated with it for viewing the parent's child nodes one page of nodes at a time. The node scroller includes paging buttons and may also include a scroll bar with a slider. The node scroller may be displayed on the parent node itself or on the links connecting the parent node to the page of children currently being displayed. Also disclosed are details of the implementation of a preferred embodiment of the node scroller and details of an application programmer's interface (API) for creating and manipulating node scrollers.

Abstract: An optimization of the two-phase commit protocol employed in distributed systems. Each cohort component of the distributed system augments messages that are accessible to the coordinator component with state information indicating whether the cohort is read-only with regard to a transaction that the coordinator is coordinating. The coordinator retains the most recent state information. The coordinator reads the retained state information for the cohorts and when the transaction terminates, the coordinator reads the retained state information. Where the cohort's state is read-only, the coordinator simply sends an abort message instead of performing the full two-phase commit protocol with regard to the read-only cohort. In the trees of distributed system components that are defined by transactions, any cohort which has children in the tree is a local coordinator for its children.