Abstract: Communication costs are reduced in a distributed system that supports data replication with conflict detection by sending small values or nulls as replacements for field values that are not strictly used for replication or conflict detection. Specifically, nulls are propagated for new values of unmodified fields, old values of fields in unmodified groups of linked fields, and old values of fields for which conflict detection has been disabled. Flag values that indicate which actual old and new values were sent may be generated and propagated along with the replicated data.

Abstract: A method and apparatus for replicating data among sites is provided. The method allows changes to the same body of data to be replicated synchronously to some destination sites and asynchronously to other destination sites. Such mixed propagation configurations allow synchronous updating to selected remote copies of replicated data where data integrity is a high priority, and asynchronous propagation to remaining copies of replicated data in order to allow transactions to be committed locally regardless of whether the transaction is committed at a remote copy of the replicated data. The propagation mode is selectable by a user on a site-to-site basis for each replicated body of data, thus providing a mix of availability and consistency that is not possible in purely synchronous or purely asynchronous replication systems.

Abstract: An in-line trigger is a modular, compiled, template trigger, which defines a series of actions to be performed when an operation is applied to a body of data. The series of actions to be performed when an in-line trigger fires are compiled into machine language instructions that receive three kinds of parameters: trigger-type specific parameters, operational metadata, and operational data. Trigger-type specific parameters are loaded into a section of run-time memory once for multiple firings of the same trigger. Operational metadata and operational data are loaded each time the trigger fires.

Abstract: An apparatus and method for providing adaptable and configurable conflict resolution within a replicated data environment is disclosed.

Abstract: A distributed system modeler for modeling a distributed system architecture. The distributed system modeler includes logic for receiving interdependency information specifying interdependencies between a plurality of data objects and programs, logic for defining a plurality of modules, wherein each module of the plurality of modules represents a different grouping of a portion of the plurality of data objects and programs, logic for assigning the modules to nodes in a distributed system, and logic for assigning a distributed transfer methodology between modules in the distributed system. The distributed system modeler includes logic for generating impact analysis criteria defining a quality of said distributed system. The impact analysis criteria includes performance metrics, conflict metrics, data object or program availability metrics, and transaction consistency metrics.