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Ensemble is the next generation of the Horus
group communication toolkit. Developed at Cornell University, as well as at
the Hebrew University of
Jerusalem.
Language supportThe current distribution provides support for
applications developed in ML, C, C++, and Java.
- ML: Ensemble is implemented in the Objective Caml programming
language (a dialect of ML). The use of ML supports a variety of
optimizations that enable Ensemble to achieve communication latencies an
order of magnitude faster than Horus (some of these optimizations are
still under research)
- Native C interface. Since version 1.31, the system includes a
native C interface whereby an application can send
io-vectors directly to the network. Received message are
copied directly into user buffers. This facilitates a C
interface that has the same performance as the ML interface
- C++: Maestro
Group Tools provide an object-oriented interface to Ensemble.
- Native Java interface. Since version 1.38, the
system includes native Java interface. This allows
Java applications to tap the power of Ensemble without
having to step out of the Java virtual
machine. Preliminary performance assessments show good
latency and throughput.
Building applications with EnsembleFor an application builder,
Ensemble provides a library of protocols that can be used for quickly
building complex distributed applications. An application registers 10 or
so event handlers with Ensemble, and then the Ensemble protocols handle
the details of reliably sending and receiving messages, transferring
state, implementing security, detecting failures, and managing
reconfigurations in the system.
A research toolFor a distributed systems researcher, Ensemble is
a highly modular and reconfigurable toolkit. The high-level protocols
provided to applications are really stacks of tiny protocol "layers."
These protocol layers each implement several simple properties: they are
composed to provide sets of high-level properties, such as total ordering,
security, virtual synchrony, etc.... Individual layers can be modified or
rebuilt to experiment with new properties or change the performance
characteristics of the system. This makes Ensemble a very flexible
platform on which to do research. |
