179 research outputs found
Leveraging TLA+ Specifications to Improve the Reliability of the ZooKeeper Coordination Service
ZooKeeper is a coordination service, widely used as a backbone of various
distributed systems. Though its reliability is of critical importance, testing
is insufficient for an industrial-strength system of the size and complexity of
ZooKeeper, and deep bugs can still be found. To this end, we resort to formal
TLA+ specifications to further improve the reliability of ZooKeeper. Our
primary objective is usability and automation, rather than full verification.
We incrementally develop three levels of specifications for ZooKeeper. We first
obtain the protocol specification, which unambiguously specifies the Zab
protocol behind ZooKeeper. We then proceed to a finer grain and obtain the
system specification, which serves as the super-doc for system development. In
order to further leverage the model-level specification to improve the
reliability of the code-level implementation, we develop the test
specification, which guides the explorative testing of the ZooKeeper
implementation. The formal specifications help eliminate the ambiguities in the
protocol design and provide comprehensive system documentation. They also help
find critical deep bugs in system implementation, which are beyond the reach of
state-of-the-art testing techniques. Our specifications have been merged into
the official Apache ZooKeeper project
Boosting API Recommendation with Implicit Feedback
Developers often need to use appropriate APIs to program efficiently, but it
is usually a difficult task to identify the exact one they need from a vast of
candidates. To ease the burden, a multitude of API recommendation approaches
have been proposed. However, most of the currently available API recommenders
do not support the effective integration of users' feedback into the
recommendation loop. In this paper, we propose a framework, BRAID (Boosting
RecommendAtion with Implicit FeeDback), which leverages learning-to-rank and
active learning techniques to boost recommendation performance. By exploiting
users' feedback information, we train a learning-to-rank model to re-rank the
recommendation results. In addition, we speed up the feedback learning process
with active learning. Existing query-based API recommendation approaches can be
plugged into BRAID. We select three state-of-the-art API recommendation
approaches as baselines to demonstrate the performance enhancement of BRAID
measured by Hit@k (Top-k), MAP, and MRR. Empirical experiments show that, with
acceptable overheads, the recommendation performance improves steadily and
substantially with the increasing percentage of feedback data, comparing with
the baselines.Comment: 15 pages, 4 figure
Mucosal Immunization Induces a Higher Level of Lasting Neutralizing Antibody Response in Mice by a Replication-Competent Smallpox Vaccine: Vaccinia Tiantan Strain
The possible bioterrorism threat using the variola virus, the causative agent of smallpox, has promoted us to further investigate the immunogenicity profiles of existing vaccines. Here, we study for the first time the immunogenicity profile of a replication-competent smallpox vaccine (vaccinia Tiantan, VTT strain) for inducing neutralizing antibodies (Nabs) through mucosal vaccination, which is noninvasive and has a critical implication for massive vaccination programs. Four different routes of vaccination were tested in parallel including intramuscular (i.m.), intranasal (i.n.), oral (i.o.), and subcutaneous (s.c.) inoculations in mice. We found that one time vaccination with an optimal dose of VTT was able to induce anti-VTT Nabs via each of the four routes. Higher levels of antiviral Nabs, however, were induced via the i.n. and i.o. inoculations when compared with the i.m. and s.c. routes. Moreover, the i.n. and i.o. vaccinations also induced higher sustained levels of Nabs overtime, which conferred better protections against homologous or alternating mucosal routes of viral challenges six months post vaccination. The VTT-induced immunity via all four routes, however, was partially effective against the intramuscular viral challenge. Our data have implications for understanding the potential application of mucosal smallpox vaccination and for developing VTT-based vaccines to overcome preexisting antivaccinia immunity
sSgo1, a Major Splice Variant of Sgo1, Functions in Centriole Cohesion Where It Is Regulated by Plk1
SummaryShugoshin 1 (Sgo1) functions as a protector of centromeric cohesion of sister chromatids in higher eukaryotes. Here, we provide evidence for a previously unrecognized role for Sgo1 in centriole cohesion. Sgo1 depletion via RNA interference induces the formation of multiple centrosome-like structures in mitotic cells that result from the separation of paired centrioles. Sgo1+/− mitotic murine embryonic fibroblasts display split centrosomes. Localization study of two major endogenous splice variants of Sgo1 indicates that the smaller variant, sSgo1, is found at the centrosome in interphase and at spindle poles in mitosis. sSgo1 interacts with Plk1 and its spindle pole localization is Plk1 dependent. Centriole splitting induced by Sgo1 depletion or expression of a dominant negative mutant is suppressed by ectopic expression of sSgo1 or by Plk1 knockdown. Our studies strongly suggest that sSgo1 plays an essential role in protecting centriole cohesion, which is partly regulated by Plk1
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