M. Díaz-Fondón, D. Álvarez-Gutiérrez, A. García-Mendoza-Sánchez, F. Álvarez-García, L. Tajes-Martínez, J.M. Cueva-Lovelle
Protection is increasingly a concern for heterogeneous distributed interoperable environments that are appearing. Oviedo3 is an example of an Integral Object-Oriented System (IOOS) based solely on the OO paradigm, developed over an OO Abstract Machine (OOAM) and OO operating system (OOOS). Integrating capabilities into the object model of the abstract machine gives capabilities new advantages. Examples are automatic protection of capabilities and specially the possibility of more flexible security policies with fine-grained protection. These benefits can also be applied to similar systems lacking this uniform protection mechanism, like Java, making them more suitable for these new environments. A prototype implementation is described with a special permission included to improve performance. Examination of preliminary performance figures together with behaviour of real-world applications and static analysis techniques, point to a favourable cost-benefit balance.
{"title":"Integrating capabilities into the object model to protect distributed object systems","authors":"M. Díaz-Fondón, D. Álvarez-Gutiérrez, A. García-Mendoza-Sánchez, F. Álvarez-García, L. Tajes-Martínez, J.M. Cueva-Lovelle","doi":"10.1109/DOA.1999.794067","DOIUrl":"https://doi.org/10.1109/DOA.1999.794067","url":null,"abstract":"Protection is increasingly a concern for heterogeneous distributed interoperable environments that are appearing. Oviedo3 is an example of an Integral Object-Oriented System (IOOS) based solely on the OO paradigm, developed over an OO Abstract Machine (OOAM) and OO operating system (OOOS). Integrating capabilities into the object model of the abstract machine gives capabilities new advantages. Examples are automatic protection of capabilities and specially the possibility of more flexible security policies with fine-grained protection. These benefits can also be applied to similar systems lacking this uniform protection mechanism, like Java, making them more suitable for these new environments. A prototype implementation is described with a special permission included to improve performance. Examination of preliminary performance figures together with behaviour of real-world applications and static analysis techniques, point to a favourable cost-benefit balance.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114982000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the fundamental differences between a centralized system and a distributed one is the notion of partial failures. The ability to efficiently and accurately detect failures is a key element underlying reliable distributed computing. In current distributed systems, however, failure detection is either left to the application developer or hidden from the programmer and provided in an ad-hoc manner behind the scenes. We plead for an intermediate approach where failure detectors are first-class objects. We view failure detection as an abstraction, the complexity of which is encapsulated behind well-defined interfaces. The various roles of a failure detection service are all represented as first-class objects. Following our approach, one can reuse existing failure detection protocols as they are, or, through composition or refinement, one can define new protocols that match the application requirements. We describe an interesting result of a composition that mixes push and pull failure monitoring, and we show how scalability issues may be addressed by using a hierarchical failure detection configuration. We also discuss the implementation of our failure service both in CORBA and in Java.
{"title":"Failure detectors as first class objects","authors":"P. Felber, X. Défago, R. Guerraoui, Philipp Oser","doi":"10.1109/DOA.1999.794001","DOIUrl":"https://doi.org/10.1109/DOA.1999.794001","url":null,"abstract":"One of the fundamental differences between a centralized system and a distributed one is the notion of partial failures. The ability to efficiently and accurately detect failures is a key element underlying reliable distributed computing. In current distributed systems, however, failure detection is either left to the application developer or hidden from the programmer and provided in an ad-hoc manner behind the scenes. We plead for an intermediate approach where failure detectors are first-class objects. We view failure detection as an abstraction, the complexity of which is encapsulated behind well-defined interfaces. The various roles of a failure detection service are all represented as first-class objects. Following our approach, one can reuse existing failure detection protocols as they are, or, through composition or refinement, one can define new protocols that match the application requirements. We describe an interesting result of a composition that mixes push and pull failure monitoring, and we show how scalability issues may be addressed by using a hierarchical failure detection configuration. We also discuss the implementation of our failure service both in CORBA and in Java.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129220525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Initial implementations of middleware based on standards such as CORBA have concentrated on host and language transparency issues in order to demonstrate interoperability. They have largely adopted a no-replication approach and have frequently neglected performance-at-scale issues. This has led to continuing deployment of either non-scalable full-replication approaches or ad-hoc messaging-based middleware for applications such as intelligent networks, WWW applications and collaborative virtual reality. These applications require millions of objects globally distributed across hundreds of hosts and demand a very high throughput of low-latency method invocations. Our main research aim is to be able to reason about the performance of such applications when using scalable partial-replication and object-oriented approaches to middleware. Our approach is to use a simulator to explore potential design and implemention choices. Our current simulator-driven design, called "MinORB", has been fully implemented and tested. MinORB supports scalable high performance by a combination of techniques, including weak and application-specified consistency and partial replication using fine-grained proxy caching. Experimental results show that our work compares very favourably with other leading implementations, such as OmniORB. Scalability is unparalleled, with up to 1,000,000,000 objects per address space, a maximum throughput of 42,000 invocations per second and service times as low as 4 ms.
{"title":"High performance distributed objects using caching proxies for large scale applications","authors":"Paul Martin, V. Callaghan, A. Clark","doi":"10.1109/DOA.1999.793995","DOIUrl":"https://doi.org/10.1109/DOA.1999.793995","url":null,"abstract":"Initial implementations of middleware based on standards such as CORBA have concentrated on host and language transparency issues in order to demonstrate interoperability. They have largely adopted a no-replication approach and have frequently neglected performance-at-scale issues. This has led to continuing deployment of either non-scalable full-replication approaches or ad-hoc messaging-based middleware for applications such as intelligent networks, WWW applications and collaborative virtual reality. These applications require millions of objects globally distributed across hundreds of hosts and demand a very high throughput of low-latency method invocations. Our main research aim is to be able to reason about the performance of such applications when using scalable partial-replication and object-oriented approaches to middleware. Our approach is to use a simulator to explore potential design and implemention choices. Our current simulator-driven design, called \"MinORB\", has been fully implemented and tested. MinORB supports scalable high performance by a combination of techniques, including weak and application-specified consistency and partial replication using fine-grained proxy caching. Experimental results show that our work compares very favourably with other leading implementations, such as OmniORB. Scalability is unparalleled, with up to 1,000,000,000 objects per address space, a maximum throughput of 42,000 invocations per second and service times as low as 4 ms.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121601958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Technology advances in digital imaging modalities and high speed network have enabled physicians to store digital medical images and integrate them with a patient's text information for fast access by computer. The Picture Archiving and Communication System (PACS) is an archival system for digital medical images. It can deliver images to a physician through user friendly interfaces for interpretation, diagnosis and study. While these technology advances support a large-scale filmless environment in radiology departments, they do not adequately support workflow management. Thus they have very limited use for streamline, automated, and monitoring processes. The paper presents the characteristics and system requirements of an Image Workflow Management System (IWFMS) in a large-scale consortium of hospitals. The paper outlines a run-time object oriented architecture for the implementation of IWFMS. This system is general purpose, open and consists of three layers: coordination, service and tasks. The components in each layer have been designed and implemented as a set of CORBA services that provides seamless integration of flexible high level CORBA distributed object computing middleware with low level image data management.
{"title":"CORBA-based architecture for image workflow in a large consortium of hospitals","authors":"O. Bukhres, Dong Hoang","doi":"10.1109/DOA.1999.794040","DOIUrl":"https://doi.org/10.1109/DOA.1999.794040","url":null,"abstract":"Technology advances in digital imaging modalities and high speed network have enabled physicians to store digital medical images and integrate them with a patient's text information for fast access by computer. The Picture Archiving and Communication System (PACS) is an archival system for digital medical images. It can deliver images to a physician through user friendly interfaces for interpretation, diagnosis and study. While these technology advances support a large-scale filmless environment in radiology departments, they do not adequately support workflow management. Thus they have very limited use for streamline, automated, and monitoring processes. The paper presents the characteristics and system requirements of an Image Workflow Management System (IWFMS) in a large-scale consortium of hospitals. The paper outlines a run-time object oriented architecture for the implementation of IWFMS. This system is general purpose, open and consists of three layers: coordination, service and tasks. The components in each layer have been designed and implemented as a set of CORBA services that provides seamless integration of flexible high level CORBA distributed object computing middleware with low level image data management.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133031590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Moser, P. Melliar-Smith, P. Narasimhan, R. Koch, K. Berket
Multicast group communication is a useful augmentation to CORBA both for fault-tolerant and highly available applications and for groupware and cooperative work applications. However, different multicast group communication protocols are appropriate in different environments, e.g. local area vs. wide area networks, and Internet vs. ATM. In this paper, we present a multicast group communication engine and bridge for CORBA that allows different multicast group communication protocols to cooperate. The group communication engine places Lamport timestamps on messages, and multicasts messages to object groups using one or more group communication protocols. The group communication protocols reliably deliver the timestamped messages in timestamp order to the group communication engine, which integrates these streams of messages into a single stream for delivery in timestamp order.
{"title":"Multicast group communication for CORBA","authors":"L. Moser, P. Melliar-Smith, P. Narasimhan, R. Koch, K. Berket","doi":"10.1109/DOA.1999.793993","DOIUrl":"https://doi.org/10.1109/DOA.1999.793993","url":null,"abstract":"Multicast group communication is a useful augmentation to CORBA both for fault-tolerant and highly available applications and for groupware and cooperative work applications. However, different multicast group communication protocols are appropriate in different environments, e.g. local area vs. wide area networks, and Internet vs. ATM. In this paper, we present a multicast group communication engine and bridge for CORBA that allows different multicast group communication protocols to cooperate. The group communication engine places Lamport timestamps on messages, and multicasts messages to object groups using one or more group communication protocols. The group communication protocols reliably deliver the timestamped messages in timestamp order to the group communication engine, which integrates these streams of messages into a single stream for delivery in timestamp order.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"152 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133659001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yue-Shan Chang, Hsin-Chun Hsieh, S. Yuan, Win-Tsung Lo
Search services are important tools in the World Wide Web. In general, these standard Web search engines are far from ideal. Many researchers have therefore implemented the multi-engine search service (MESS) using meta-broker. However these MESS prove difficult when integrating a new search engine. On the other hand, applications that need the search service ability also prove difficult using these MESS. In this paper we propose an Internet search service (ISS) based on CORBA. We follow the style of Common Object Service Specification to define the interface of ISS, so that it is not only easily to integrate any search engine into multi-search services, but can also be queried by application programs. In addition, two search engine agents are implemented in our project, one is for Yahoo and the other is for AltaVista. Programmers can use this interface to code their search engine agent or to query the search service in their applications. Finally, we build a heterogeneous search engine agent based on this architecture.
搜索服务是万维网的重要工具。一般来说，这些标准的Web搜索引擎还远远不够理想。因此，许多研究者利用元代理实现了多引擎搜索服务(MESS)。然而，当整合一个新的搜索引擎时，这些混乱被证明是困难的。另一方面，需要搜索服务功能的应用程序也很难使用这些MESS。本文提出了一种基于CORBA的互联网搜索服务(ISS)。我们遵循公共对象服务规范(Common Object Service Specification)的风格来定义ISS的接口，这样不仅可以方便地将任何搜索引擎集成到多搜索服务中，而且还可以被应用程序查询。此外，在我们的项目中实现了两个搜索引擎代理，一个是Yahoo，另一个是AltaVista。程序员可以使用这个接口编写他们的搜索引擎代理，或者在他们的应用程序中查询搜索服务。最后，在此基础上构建了一个异构搜索引擎代理。
{"title":"An agent-based search engine based on the Internet search service on the CORBA","authors":"Yue-Shan Chang, Hsin-Chun Hsieh, S. Yuan, Win-Tsung Lo","doi":"10.1109/DOA.1999.793979","DOIUrl":"https://doi.org/10.1109/DOA.1999.793979","url":null,"abstract":"Search services are important tools in the World Wide Web. In general, these standard Web search engines are far from ideal. Many researchers have therefore implemented the multi-engine search service (MESS) using meta-broker. However these MESS prove difficult when integrating a new search engine. On the other hand, applications that need the search service ability also prove difficult using these MESS. In this paper we propose an Internet search service (ISS) based on CORBA. We follow the style of Common Object Service Specification to define the interface of ISS, so that it is not only easily to integrate any search engine into multi-search services, but can also be queried by application programs. In addition, two search engine agents are implemented in our project, one is for Yahoo and the other is for AltaVista. Programmers can use this interface to code their search engine agent or to query the search service in their applications. Finally, we build a heterogeneous search engine agent based on this architecture.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126089258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
DCOM (Distributed Component Object Model) and CORBA (Common Object Request Broker Architecture) are two major solutions to develop distributed applications. Each of them uses its own functionality, for instance the communication protocols: ORPC (Object Remote Procedure Call) in the case of DCOM and IIOP (Internet Inter-ORB Protocol) for CORBA. That is why a DCOM client cannot co-operate with a CORBA server without a gateway. We propose an alternative approach to allow generic inter-working between these environments without gateways. Actually, we present a model called "Active COM", which provides native inter-working between CORBA and DCOM.
{"title":"Active COM: an inter-working framework for CORBA and DCOM","authors":"J. Daniel, B. Traverson, Vincent Vallée","doi":"10.1109/DOA.1999.794029","DOIUrl":"https://doi.org/10.1109/DOA.1999.794029","url":null,"abstract":"DCOM (Distributed Component Object Model) and CORBA (Common Object Request Broker Architecture) are two major solutions to develop distributed applications. Each of them uses its own functionality, for instance the communication protocols: ORPC (Object Remote Procedure Call) in the case of DCOM and IIOP (Internet Inter-ORB Protocol) for CORBA. That is why a DCOM client cannot co-operate with a CORBA server without a gateway. We propose an alternative approach to allow generic inter-working between these environments without gateways. Actually, we present a model called \"Active COM\", which provides native inter-working between CORBA and DCOM.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121809200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As the leading vendor of enterprise business standard software, SAP has recognized the need to adapt their R/3 system to current trends in software development and to meet market needs for speed of development, flexibility, openness and interoperability. We first present SAP's approach to object oriented and component based technology by describing the Business Framework, the concepts of Business Objects, BAPIs, and the Business Object Repository. On this basis, we then analyze current communication architectures and products enabling the interaction of external Java based software applications with SAP R/3, point out the advantages and disadvantages of different solutions and finally elaborate on potential strategies and steps for driving the evolution of SAP R/3 in order to further increase interoperability openness and flexibility.
{"title":"Interoperability of Java-based applications and SAP's business framework state of the art and desirable developments","authors":"M. Aleksy, Axel Korthaus","doi":"10.1109/DOA.1999.794024","DOIUrl":"https://doi.org/10.1109/DOA.1999.794024","url":null,"abstract":"As the leading vendor of enterprise business standard software, SAP has recognized the need to adapt their R/3 system to current trends in software development and to meet market needs for speed of development, flexibility, openness and interoperability. We first present SAP's approach to object oriented and component based technology by describing the Business Framework, the concepts of Business Objects, BAPIs, and the Business Object Repository. On this basis, we then analyze current communication architectures and products enabling the interaction of external Java based software applications with SAP R/3, point out the advantages and disadvantages of different solutions and finally elaborate on potential strategies and steps for driving the evolution of SAP R/3 in order to further increase interoperability openness and flexibility.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134322292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Barth, Gerd Flender, Bernd Freisleben, F. Thilo
The design and implementation of a CORBA load distribution service for distributed scientific computing applications running in a network of workstations is described. The proposed approach is based on integrating load distribution into the CORBA naming service which in turn relies on information provided by the underlying WINNER resource management system developed for typical networked Unix workstation environments. The necessary extensions to the naming service, the WINNER features for collecting load information and the placement decisions are described. A prototypical implementation of the complete system is presented, and performance results obtained for the parallel optimization of a mathematical test function are discussed.
{"title":"Load distribution in a CORBA environment","authors":"T. Barth, Gerd Flender, Bernd Freisleben, F. Thilo","doi":"10.1109/DOA.1999.794010","DOIUrl":"https://doi.org/10.1109/DOA.1999.794010","url":null,"abstract":"The design and implementation of a CORBA load distribution service for distributed scientific computing applications running in a network of workstations is described. The proposed approach is based on integrating load distribution into the CORBA naming service which in turn relies on information provided by the underlying WINNER resource management system developed for typical networked Unix workstation environments. The necessary extensions to the naming service, the WINNER features for collecting load information and the placement decisions are described. A prototypical implementation of the complete system is presented, and performance results obtained for the parallel optimization of a mathematical test function are discussed.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123957896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper describes PJRMI: support for remote method invocation in the context of the object oriented, orthogonally persistent system of the PJama project. It examines the issues raised by combining orthogonal persistence with distribution. An evaluation is made of the current implementation and an indication is made of the challenges ahead.
{"title":"PJRMI: remote method invocation for a persistent system","authors":"Susan Spence","doi":"10.1109/DOA.1999.793983","DOIUrl":"https://doi.org/10.1109/DOA.1999.793983","url":null,"abstract":"The paper describes PJRMI: support for remote method invocation in the context of the object oriented, orthogonally persistent system of the PJama project. It examines the issues raised by combining orthogonal persistence with distribution. An evaluation is made of the current implementation and an indication is made of the challenges ahead.","PeriodicalId":360176,"journal":{"name":"Proceedings of the International Symposium on Distributed Objects and Applications","volume":"203 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131481739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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