摘要:

AbstractThis paper tackles the practical aspects of obtaining a distributed version of an Ada program. It proposes the use of an adapter, which can be a methodology or an automatic translator. The adapter accepts source of a concurrent Ada program, adds communication and control tasks, and produces source for a single distributed Ada program, which can then be compiled and run on a multi‐processor computer. The original program can consist of packages and tasks, and both of these can be classed as virtual nodes. The process of adaption does not alter the contents of any package in the original program, so that the method is directly applicable to systems that make use of library and generic packages. The communication between virtual nodes, which would normally reside as one per processor, is via messages on a ring, but the protocols are kept as simple as possible, and the messages are fully checked Ada types, rather than byte strings. The method has been applied to programs of the client‐server model, and could be adapted for other rendezvous‐based languages such as

ISSN:0038-0644    

DOI:10.1002/spe.4380171202

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe Computer Networks Laboratory at the University of Virginia has developed a real‐time messaging service that runs on IBM PCs and PC/ATs when interconnected with a Proteon ProNET‐10 token ring local area network. The system is a prototype for a real‐time communications network to be used aboard ships. The system conforms to the IEEE 802.2 logical link control standard for type I (connectionless, or datagram) service, with an option for acknowledged datagrams.The application environment required substantial network throughput and bounded message delay. Thus, the development philosophy was to emphasize performance initially and to offer only primitive user services. After providing and measuring the performance of a basic datagram service, the intent is to add additional user services one at a time and to retain only those which the user can ‘afford’ in terms of their impact on throughput, delay, and CPU utilization.The current system is programmed in C. The user interface is a set of C procedure calls that initialize tables, reserve buffer space, send and receive messages, and report network status. The system is now operational, and initial performance measurements are complete. Using this system, an individual PC can transmit or receive approximately 200 short (about 100 bytes) messages per second, and the PC/AT operates at nearly 500 short messages p

ISSN:0038-0644    

DOI:10.1002/spe.4380171203

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe Object‐Oriented Program Support (OOPS) class library is a portable collection of classes similar to those of Smalltalk‐80 that has been developed using the C++ programming language under the UNIX operating system. The OOPS library includes generally useful data types, such as String, Date and Time, and most of the Smalltalk‐80 collection classes such as OrderedCtn (indexed arrays), LinkedList (singly linked lists), Set (hash tables), and Dictionary (associative arrays). Arbitrarily complex data structures comprised of OOPS and user‐defined objects can be stored on disk files or moved between UNIX processes by means of an object I/O facility. The classes Process, Scheduler, Semaphore and SharedQueue provide multiprogramming with coroutines. This paper gives a brief introduction to object‐oriented programming and how it is supported by the C+ + programming language. An overview of the OOPS library is also presented, followed by a programming example. The implementation details of two of the class library's more interesting features, object I/O and processes, are described. The paper concludes with a discussion of the differences between the OOPS library and Smalltalk‐80 and some observations based on our programming experience with C

ISSN:0038-0644    

DOI:10.1002/spe.4380171204

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper describes two mechanisms –reproduction sets and metafiles– that provide low‐cost, semi‐automatic file replication and location transparency facilities for an interconnected collection of machines running Berkeley Unix. A reproduction set is a collection of files that the system attempts to keep identical; this is done on a ‘best effort’ basis, with the system relying on the user to handle unusual situations. A metafile is a special file that contains symbolic pathnames of other files, each of which may be on any machine in the network; opening a metafile results in opening an available constituent file. Examples are given to illustrate the use of these mechanisms. Their implementation and performance are als

ISSN:0038-0644    

DOI:10.1002/spe.4380171205

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0038-0644    

DOI:10.1002/spe.4380171201

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY