L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, pages 130-139, Niagara-on-the-Lake, Canada, October 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....the timewheel group membership protocol. These two protocols along with a clock synchronization protocol [24] comprise the timewheel group communication system. The timewheel group communication system provides four unique characteristics that distinguish it from other group communication services [12, 8, 44, 52, 9, 3, 39, 4, 21, 50, 45, 19, 5, 7]. First, this system has been designed for a timed asynchronous distributed system model [18] Timed asynchronous distributed system model has been proposed recently. It allows the construction of dependable protocols that specify what outputs and state transitions should occur in response to ....

....even distribution of processing load among group members, and high throughput. 32 Research in the design and implementation of group communication services is still going on. Recent focus has been on their deployment in a wide area networking environment [33, 2] scalability in terms group size [45, 7, 49], and their operation in a heterogeneous, distributed computing environment [22, 37] Timeliness of group communication services in a non synchronous, distributed computing environment has not been addressed much. This has been a major limitation of group communication services. The timewheel ....

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verissimo, and K. Birman. A transparent light-weight group service. In 15th IEEE SRDS, pages 130--139, Niagara-on-the-Lake, Canada, Oct 1996.

....to support CORBA object replication with Isis and Horus [35] Several designers of process group communication toolkits have recognised the mismatch between object groups and process groups. For instance, some experiments with the notion of light weight group have recently been done in Horus [43]. A light weight process group is mapped onto an object group, and several light weight groups are mapped onto one single process group, amortising the cost of many membership changes (Section 2.2.1) This indeed limits the impact of the mismatch (namely overlapping groups) but does not solve all ....

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verissimo, and K. Birman. A Transparent Light-Weight Group Service. IEEE Symposium on Reliable Distributed Systems, 1996, 130-139.

....activities) and site groups of the sites where those participants reside (performing reliable communication on behalf of the latter) is beneficial to application structuring. This can be further enhanced by mapping more than one group onto the same sitegroup, in what are called lightweight groups [Rodrigues et al. 1996]. The Activity Support Services depend on the participant membership information. The protocols implementing the layers described above fulfil the topology awareness property. As such, they may run differently depending on their position in the topology, although this happens transparently. For ....

L. Rodrigues, K. Guo, A. Sargento, R. v. Renesse, B. Glade, P. Verissimo and K. Birman, "A Transparent Light-Weight Group Service", in Proc. 15th Int. Conf. on FaultTolerant Computing Systems (FTCS-15), (Niagra-on-the-Lake, Canada), pp.130-9, IEEE CS, 1996.

....to support CORBA object replication with Isis and Horus [33] Several designers of process group communication toolkits have recognised the mismatch between object groups and process groups. For instance, some experiments with the notion of light weight group have recently been done in Horus [41]. A light weight process group is mapped onto an object group, and several light weight groups are mapped onto one single process group, amortising the cost of many membership changes (Section 2.2.1) This indeed limits the impact of the mismatch (namely overlapping groups) but does not solve all ....

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verissimo, and K. Birman. A Transparent Light-Weight Group Service. IEEE Symposium on Reliable Distributed Systems, 1996, 130-139.

....current leader and r is the second oldest channel member. On receipt of fail q , r flushes. If VCR messages remain unanswered, r assumes leadership and responds with VCA r . Conflicting VCA messages are not possible because new leaders must flush before assuming leadership. Similar protocols [3, 23, 10] flush at every view change. This is because they requires messages to be delivered in the same view sent. Before a view change, they need to flush all the messages sent in the current view. In our protocol, flush is required only when some process fails to force agreement on which messages of ....

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verissimo, K. Birman, "A transparent light-weight group service", in the proceedings of 15th IEEE Symposium on Reliable Distributed Systems, Oct., 1996.

....resources cannot be shared among related groups. In addition, Horus membership protocols require an underlying reliable transport making it very difficult to implement unreliable channels with reliable membership. A light weight group service for Horus has recently been implemented and described [19]. Horus lightweight groups (LWGs) may be mapped dynamically to heavy weight groups (HWGs) However, LWGs are essentially multiplexed using a single HWG. Messages sent to a particular LWG are actually delivered to all members of the HWG (and filtered out by nonmembers of the LWG) LWGs effectively ....

....guarantees for regular messages. The QoS module also provides an interface to lower level network protocols such as IP multicast or UDP and handles inter network routing (IPmulticast to a LAN, UDP over WANs) Several researchers have proposed communication systems supporting light weight groups [19]. These systems support the dynamic mapping of many lightweight groups to a small set of heavy weight groups. CCTL statically binds light weight channels to a single heavy weight session, mirroring the semantics of CSCW environments. Session participants initiate multiple tools that communicate ....

[Article contains additional citation context not shown here]

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verissimo, K. Birman, "A transparent light-weight group service", in the proceedings of 15th IEEE Symposium on Reliable Distributed Systems, Oct., 1996.

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L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, pages 130-139, Niagara-on-the-Lake, Canada, October 1996.

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L Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Ver'issimo, and K. Birman. A transparent light-weight group service. Technical report, INESC/ Cornell Univ., 1996. (submitted for publication).

.... As a test case, the new protocols were implemented in the Horus system [27] as a new protocol layer) but the underlying principles can be applied to other architectures (including the Isis [12] and NavTech [29] systems) The paper integrates and expands two previous conference publications [24, 14]. The new set of protocols have important advantages when there is large overlap among user groups. This paper discusses how these protocols can be applied in environments where mappings cannot be defined a priori and may change over time. We show how to establish mappings that promote resource ....

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Ver ssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, pages 130--139, Niagara-on-the-Lake, Canada, October 1996.

....Group Service. Light Weight Group Services have been implemented before in different group based communication systems [4, 6] Unfortunately, such services did not preserve the exact interface of the underlying virtually synchronous group, imposing restrictions on group usage. In a recent paper [7], we have proposed a new design for the Lwg protocols that circumvents such limitations, in particular, we have shown that the Light Weight Group Service can be implemented in a fully transparent manner. This new set of protocols has already proven to be advantageous in static environments, where ....

....by mapping several Lwgs onto a single Hwg , the implementation of mapping and switching strategies becomes pointless. Due to this reason, we have first concentrated on developing and evaluating the protocols that support the transparent Lwg design. These protocols are described in detail elsewhere [7]. For self containment, the next section provides a brief description of these protocols and of their performance. Downcalls Upcalls Name Parameters Name Parameters Join GroupId gid, Pid pid View GroupId gid, PidList view Leave GroupId gid, Pid pid Data GroupId gid, Pid src, BitArray data ....

[Article contains additional citation context not shown here]

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Ver'issimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, Niagara-on-the-Lake, Canada, October 1996.

....name of lightweight groups. NAVTECH casts the hierarchy in the architecture, widening the horizon for scalability. For example, several ## modules may exist and map onto the site ## module. However, in each ## module, genuine lightweight groups may further be mapped on regular participant groups[35]. The two tier membership is also compatible with the separation of concerns between communication (##) and activity (##) pioneered in the NAVTECH architecture. The same site membership semantics may serve different participant membership semantics in the same system, according to the application ....

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, pages 130--139, Niagara-on-the-Lake, Canada, October 1996.

....results are returned as events. Several groups of participants can be mapped onto a single site group. These groups, called lightweight groups, are useful to improve performance. The API of the membership module considering lightweight groups can be the same as for normal (heavyweight) groups [38]. Therefore, the API we describe below can be used in both cases. The membership of both participant and site groups at a given instant is called a view. The concept was de ned in the context of the virtual synchrony group semantics. Informally, virtual synchrony provides membership information ....

L. Rodrigues, K. Guo, A. Sargento, R. Van Renesse, B. Gladeand, P. Verssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, Niagara-on-the-Lake, Canada, October 1996.

.... (performing distributed activities) and site groups of the sites where those participants reside (performing reliable communication on behalf of the latter) Clustering can be further enhanced by mapping more than one group onto the same site group, in what are called lightweight groups [81]. It depends on the services provided by the CS module, and on the membership information provided by the PM module. Consequentially, the protocols implementing the layers described above all share the topology awareness property. As such, they may run di erently depending on their position in ....

L. Rodrigues, K. Guo, A. Sargento, R. Van Renesse, B. Gladeand, P. Verssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, Niagara-on-the-Lake, Canada, October 1996.

.... (performing distributed activities) and site groups of the sites where those participants reside (performing reliable communication on behalf of the latter) Clustering can be further enhanced by mapping more than one group onto the same site group, in what are called lightweight groups[9]. The PM module monitors all groups with local members, depending on information propagated by the SM and by the PF modules, and operating cooperatively with the corresponding modules in the concerned remote sites. The Activity Support Services module, AS, implements building blocks that assist ....

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th 10 IEEE Symposium on Reliable Distributed Systems, pages 130-139, Niagara-onthe -Lake, Canada, Oct. 1996.

.... (performing distributed activities) and site groups of the sites where those participants reside (performing reliable communication on behalf of the latter) Clustering can be further enhanced by mapping more than one group onto the same site group, in what are called lightweight groups[9]. The PM module monitors all groups with local members, depending on information propagated by the SM and by the PF modules, and operating cooperatively with the corresponding modules in the concerned remote sites. The Activity Support Services module, AS, implements building blocks that assist ....

L.Rodrigues,K.Guo,A.Sargento,R.vanRenesse,B.Glade,P.Verssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th 10 IEEE Symposium on Reliable Distributed Systems, pages 130--139, Niagara-onthe -Lake, Canada, Oct. 1996.

....Groups (Lwgs ) In contrast, the underlying virtually synchronous group is called a Heavy Weight Group (Hwg ) A Light Weight Group Service maps Lwgs onto Hwgs . In previous work, we have designed and implemented a transparent and dynamic lightweight group service in non partitionable networks [14, 8]. In this paper, we propose extensions to address the issue of network partitions. Network partition poses several challenges to the design of a light weight group service. In particular, it is impossible to ensure the consistency of mapping decisions made in distinct partitions. Thus, ....

....Because these approaches implement a static form of a light weight group service, they do not address the problem of minimizing interference among unrelated groups. In previous work we have addressed the issue of building a transparent light weight group service in non partitionable networks [14, 8]. The work addressed the following problems raised by the transparency requirements: i) the need to perform mappings between Lwgs and Hwgs in an automatic and dynamic manner; ii) the design of mechanisms to allow these mappings to be changed in run time. Another contribution of our previous work ....

[Article contains additional citation context not shown here]

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Ver'issimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, pages 130--139, Niagara-on-the-Lake, Canada, Oct. 1996.

....after a deadline With this information the system support is able to make a decision accordingly to the QoS to be provided. Communication protocols and group management can be organized in a hierarchical way making it possible to have groups with a lower overhead on join and leave operations[12]. This can be of great importance in the handling of timing faults. The period of TFDS can be configured so as to suit application time granularity. Communication protocols are also parameterizable to the characteristics of the environment. This service as provided by the TFDS enables the ....

L Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Ver'issimo, and K. Birman. A transparent light-weight group service. Technical report, INESC/ Cornell Univ., 1996. (submitted for publication).

....Group Service. Light Weight Group Services have been implemented be fore in different group based communication systems [5, 8] Unfortunately, such services imposed restrictions on group usage as a result of changing the interface of the underlying virtually synchronous group. In a recent paper [9], we have proposed a new design for the LWG protocols that circumvents such limitations, in particular, we have shown that the Light Weight Group Service can be implemented in a fully transparent manner. This new set of protocols has already proven advantageous in static environments, where there ....

....these mappings can be automated, using heuristics applied locally at each node. Experimentsimplementing this approach in the Horus system [12] have shown significant performance improvements. The paper is organized into five other sections. Related work is surveyed in Section 2. In a recent paper [9], the design of the Transparent Light Weight Group Service is further explored, but Section 3 provides a brief description. The heuristics to support dynamic mappings are discussed in Section 4. Performance results obtained with an implementation in Horus are presented in Section 5. Section 6 ....

[Article contains additional citation context not shown here]

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Grade, P. Ver ssimo, and K. Birman. A transparent light-weight group service. In Proceedings of the 15th IEEE Symposium on Reliable Distributed Systems, pages 130--139, Niagaraon -the-Lake, Canada, October 1996.

No context found.

L. Rodrigues, K. Guo, A. Sargento, R. van Renesse, B. Glade, P. Verisimo, and K. Birman. A Transparent Light-Weight Group Service. In 15th IEEE Symposium on Reliable Distributed Systems, p.130-139, Niagara-on-the-Lake, Canada, October 1996.

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