Abstract: This disclosure presents a technique of field-level caching in distributed object-oriented systems, in which a speculative approach is taken to identify opportunities for caching. The speculative approach is particularly suitable for exploitation of opportunities for caching. Invalidation protocols, which are fully compliant with the Java memory model, are provided to recover from incorrect speculation, while incurring only a low overhead. The technique has been implemented on a cluster of machines, and has been found to be readily scalable with multi-threaded applications. Field caching, optionally combined with other optimizations, produces a practically important performance step up in distributed environments, such as the cluster virtual machine for Java, which transparently distributes an application's threads and objects among the nodes of a cluster.

Abstract: A method for performing remote calls between source and target computing machines includes running a program thread on the source machine which invokes a remote call to the target machine. The remote call is transmitted to the target machine, the call including an identifier associated with the program thread. A response to the remote call is received from the target machine, the response including the identifier, whereby the response is returned to the program thread on the source machine using the identifier.

Abstract: A method for packaging program resources includes collecting a set of the program resources that comprises a plurality of object files, which contain data structures having entries that are constants and methods that reference the entries. The data structures in at least some of the object files are combined into a common data pool, in which semantically-identical entries in different ones of the files are represented by a single consolidated entry, irrespective of whether the entries in the different files are syntactically identical. The set of the program resources is packaged together with the common data pool in a combined output file.

Abstract: A group communication system (GCS), for use within a group of clustered computing nodes, provides a flexible group membership model. Flexible group members are defined generally as physical computing entities (such as computing nodes or other devices) or logical computing entities that take part in a distributed application. Such logical entities may include substantially any combination of processes, threads and callback functions. Logical entities that are members in the group may also be objects, such as files, that at least at some times during their existence have no active processes or threads. A single member may include multiple simultaneous processes.

Abstract: A data structure and associated mechanism for implementing object oriented programming language, comprising at least two code blocks for at least one method of an object of a specified class, each of the code blocks containing a different implementation of the at least one method. An access mechanism is provided for accessing a desired code block at run-time on a per object instance basis so as to allow selection of a desired implementation of the at least one method without requiring instantiation of an object of a different class. The selection of which implementation to invoke is integrated into an existing invocation method of the language and is thus transparent to a calling application invoking the method.

Abstract: A computer system running under the control of an OS having a scheduler. The computer system includes a multi-threaded computer program that is partitioned into structures of which some are parallel. There is provided a Time-Related-Bug-Detector (TRBD) method for detecting data races between parallel structures in respect of common memory structures. The method includes performing the steps of coupling a private scheduler to the OS. Thereafter, running the program in few cycles and, during each cycle of program run, the private scheduler synchronizing the structures according to a specific interleaving of a partial order. For each cycle logging the results of the program, until every possible interleaving of the partial order has been tested. Thereafter, comparing the results, and in the case that they are identical indicating that said program is race free in a give degree of confidence, otherwise indicating that the program is susceptible to a data race in respect to a common memory.

Abstract: This disclosure presents a technique of field-level caching in distributed object-oriented systems, in which a speculative approach is taken to identify opportunities for caching. The speculative approach is particularly suitable for exploitation of opportunities for caching. Invalidation protocols, which are fully compliant with the Java memory model, are provided to recover from incorrect speculation, while incurring only a low overhead. The technique has been implemented on a cluster of machines, and has been found to be readily scalable with multi-threaded applications. Field caching, optionally combined with other optimizations, produces a practically important performance step up in distributed environments, such as the cluster virtual machine for Java, which transparently distributes an application's threads and objects among the nodes of a cluster.

Abstract: An XML-aware file system exploits attributes encoded in an XML document. The file system presents a dynamic directory structure to the user, and breaks the conventional tight linkage between sets of files and the physical directory structure, thus allowing different users to see files organized in a different fashion. The dynamic structure is based upon content, which is extracted using an inverted index according to attributes and values defined by the XML structure.